Airworthiness Chapter 525 Subchapter D - Design and Construction

From: Transport Canada

Preamble

Subchapters

A (525.1-525.3),
B (525.21-525.255),
C (525.301-525.581),
D (525.601-525.899),
E (525.901-525.1207),
F (525.1301-525.1461),
G (525.1501-525.1587)
H (525.1701-525.1733)

Appendices

A, B, C, D, E, F, G, H, I, J, K, L, M, N, O

Last amendment to subchapter D: 2024/04/05

Subchapter D - Design and Construction

525.601 General

The aeroplane may not have design features or details that experience has shown to be hazardous or unreliable. The suitability of each questionable design detail and part must be established by tests.

525.603 Materials

The suitability and durability of materials used for parts, the failure of which could adversely affect safety, must:

(a) Be established on the basis of experience or tests;
(b) Conform to approved specifications (such as industry or military specifications, or Technical Standard Orders) that ensure their having the strength and other properties assumed in the design data; and
(c) Take into account the effects of environmental conditions, such as temperature and humidity, expected in service.

525.605 Fabrication Methods

(a) The methods of fabrication used must produce a consistently sound structure. If a fabrication process (such as gluing, spot welding, or heat treating) requires close control to reach this objective, the process must be performed under an approved process specification.
(b) Each new aircraft fabrication method must be substantiated by a test program.

525.607 Fasteners

(a) Each removable bolt, screw, nut, pin, or other removable fastener must incorporate two separate locking devices if:
- (1) Its loss could preclude continued flight and landing within the design limitations of the aeroplane using normal pilot skill and strength; or
- (2) Its loss could result in the reduction in pitch, yaw, or roll control capability or response below that required by subchapter B of this chapter.
(b) The fasteners specified in paragraph (1) of this section and their locking devices may not be adversely affected by the environmental conditions associated with the particular installation.
(c) No self-locking nut may be used on any bolt subject to rotation in operation unless a non-friction locking device is used in addition to the self-locking device.

525.609 Protection of Structure

Each part of the structure must:

(a) Be suitably protected against deterioration or loss of strength in service due to any cause, including:
- (1) Weathering;
- (2) Corrosion; and
- (3) Abrasion; and
(b) Have provisions for ventilation and drainage where necessary for protection.

525.611 Accessibility Provisions

(a) Means must be provided to allow inspection (including inspection of principal structural elements and control systems), replacement of parts normally requiring replacement, adjustment, and lubrication as necessary for continued airworthiness. The inspection means for each item must be practicable for the inspection interval for the item. Non-destructive inspection aids may be used to inspect structural elements where it is impracticable to provide means for direct visual inspection if it is shown that the inspection is effective and the inspection procedures are specified in the maintenance manual required by 525.1529.
(amended 2009/05/11)
(b) EWIS must meet the accessibility requirements of 525.1719.
(amended 2009/05/11; no previous version)

525.613 Material Strength Properties and Material Design Values
(amended 2003/11/26)

(a) Material strength properties shall be based on enough tests of material meeting approved specifications to establish design values on a statistical basis.
(amended 2003/11/26)
(b) Material design values shall be chosen to minimise the probability of structural failures due to material variability. Except as provided in paragraph (e) and (f) of this section, compliance with this paragraph shall be demonstrated by selecting material design values which assure material strength with the following probability:
(amended 2003/11/26)
- (1) Where applied loads are eventually distributed through a single member within an assembly, the failure of which would result in loss of structural integrity of the component, 99 percent probability with 95 percent confidence.
- (2) For redundant structure, in which the failure of individual elements would result in applied loads being safely distributed to other load carrying members, 90 percent probability with 95 percent confidence.
(c) The effects of environmental conditions, such as temperature and moisture, on material design values used in an essential component or structure shall be considered where these effects are significant within the aeroplane operating envelope.
(amended 2003/11/26)
(d) Reserved
(amended 2003/11/26)
(e) Greater material design values may be used if a "premium selection" of the material is made in which a specimen of each individual item is tested before use to determine that the actual strength properties of that particular item will equal or exceed those used in design.
(amended 2003/11/26)
(f) Other material design values may be used if approved by the Minister.
(amended 2003/11/26; no previous version)

(Change 525-3 (91-11-01))

525.619 Special Factors

The factor of safety prescribed in 525.303 must be multiplied by the highest pertinent special factor of safety prescribed in 525.621 through 525.625 for each part of the structure whose strength is:

(a) Uncertain;
(b) Likely to deteriorate in service before normal replacement; or
(c) Subject to appreciable variability because of uncertainties in manufacturing processes or inspection methods.

525.621 Casting Factors

(a) General. For castings used in structural applications, the factors, tests, and inspections specified in paragraphs (b) through (d) of this section must be applied in addition to those necessary to establish foundry quality control. The inspections must meet approved specifications. Paragraphs (c) and (d) of this section apply to any structural castings, except castings that are pressure tested as parts of hydraulic or other fluid systems and do not support structural loads.
(effective 2019/11/01)
(b) Bearing stresses and surfaces. The casting factors specified in paragraphs (c) and (d) of this section:
- (1) Need not exceed 1.25 with respect to bearing stresses regardless of the method of inspection used; and
- (2) Need not be used with respect to the bearing surfaces of a part whose bearing factor is larger than the applicable casting factor.
(c) Critical castings. Each casting whose failure could preclude continued safe flight and landing of the aeroplane or could result in serious injury to occupants is a critical casting. Each critical casting must have a factor associated with it for showing compliance with strength and deformation requirements of 525.305, and must comply with the following criteria associated with that factor:
(effective 2019/11/01)
- (1) A casting factor of 1.0 or greater may be used, provided that:
  - (i) It is demonstrated, in the form of process qualification, proof of product, and process monitoring that, for each casting design and part number, the castings produced by each foundry and process combination have coefficients of variation of the material properties that are equivalent to those of wrought alloy products of similar composition. Process monitoring must include testing of coupons cut from the prolongations of each casting (or each set of castings, if produced from a single pour into a single mould in a runner system) and, on a sampling basis, coupons cut from critical areas of production castings. The acceptance criteria for the process monitoring inspections and tests must be established and included in the process specifications to ensure the properties of the production castings are controlled to within levels used in design.
  - (ii) Each casting receives:
    - (A) Inspection of 100 percent of its surface, using visual inspection and liquid penetrant or equivalent inspection methods; and
    - (B) Inspection of structurally significant internal areas and areas where defects are likely to occur, using a radiographic or equivalent inspection methods.
  - (iii) One casting undergoes a static test and is shown to meet the strength and deformation requirements of 525.305(a) and (b).
- (2) A casting factor of 1.25 or greater may be used, provided that:
  - (i) Each casting receives:
    - (A) Inspection of 100 percent of its surface, using visual inspection and liquid penetrant or equivalent inspection methods; and
    - (B) Inspection of structurally significant internal areas and areas where defects are likely to occur, using radiographic or equivalent inspection methods.
  - (ii) Three castings undergo static tests and are shown to meet:
    - (A) The strength requirements of 525.305(b) at an ultimate load corresponding to a casting factor of 1.25; and
    - (B) The deformation requirements of 525.305(a) at a load of 1.15 times the limit load.
- (3) A casting factor of 1.50 or greater may be used, provided that:
  - (i) Each casting receives:
    - (A) Inspection of 100 percent of its surface, using visual inspection and liquid penetrant or equivalent inspection methods; and
    - (B) Inspection of structurally significant internal areas and areas where defects are likely to occur, using radiographic or equivalent inspection methods.
  - (ii) One casting undergoes a static test and is shown to meet:
    - (A) The strength requirements of 525.305(b) at an ultimate load corresponding to a casting factor of 1.50; and
    - (B) The deformation requirements of 525.305(a) at a load of 1.15 times the limit load.
(d) Non-critical castings. For each casting other than critical castings, as specified in paragraph (c) of this section, the following apply:
(effective 2019/11/01)
- (1) A casting factor of 1.0 or greater may be used, provided that the requirements of (c)(1) of this section are met, or all of the following conditions are met:
  - (i) Castings are manufactured to approved specifications that specify the minimum mechanical properties of the material in the casting and provides for demonstration of these properties by testing of coupons cut from the castings on a sampling basis.
  - (ii) Each casting receives:
    - (A) Inspection of 100 percent of its surface, using visual inspection and liquid penetrant or equivalent inspection methods; and
    - (B) Inspection of structurally significant internal areas and areas where defects are likely to occur, using radiographic or equivalent inspection methods.
  - (iii) Three sample castings undergo static tests and are shown to meet the strength and deformation requirements of 525.305(a) and (b).
- (2) A casting factor of 1.25 or greater may be used, provided that each casting receives:
  - (i) Inspection of 100 percent of its surface, using visual inspection and liquid penetrant or equivalent inspection methods; and
  - (ii) Inspection of structurally significant internal areas and areas where defects are likely to occur, using radiographic or equivalent inspection methods.
- (3) A casting factor of 1.5 or greater may be used, provided that each casting receives inspection of 100 percent of its surface using visual inspection and liquid penetrant or equivalent inspection methods.
- (4) A casting factor of 2.0 or greater may be used, provided that each casting receives inspection of 100 percent of its surface using visual inspection methods.
- (5) The number of castings per production batch to be inspected by non-visual methods in accordance with paragraphs (d)(2) and (3) of this section may be reduced when an approved quality control procedure is established.

525.623 Bearing Factors

(a) Except as provided in paragraph (b) of this section, each part that has clearance (free fit), and that is subject to pounding or vibration, must have a bearing factor large enough to provide for the effects of normal relative motion.
(b) No bearing factor need be used for a part for which any larger special factor is prescribed.

525.625 Fitting Factors

For each fitting (a part or terminal used to join one structural member to another), the following apply:

(a) For each fitting whose strength is not proven by limit and ultimate load tests in which actual stress conditions are simulated in the fitting and surrounding structures, a fitting factor of at least 1.15 must be applied to each part of:
- (1) The fitting;
- (2) The means of attachment; and
- (3) The bearing on the joined members.
(b) No fitting factor need be used:
- (1) For joints made under approved practices and based on comprehensive test data (such as continuous joints in metal plating, welded joints, and scarf joints in wood); or
- (2) With respect to any bearing surface for which a larger special factor is used.
(c) For each integral fitting, the part must be treated as a fitting up to the point at which the section properties become typical of the member.
(d) For each seat, berth, safety belt, and harness, the fitting factor specified in 525.785(f)(3) applies.

(Change 525-3 (91-11-01))

525.629 Aeroelastic Stability Requirements

(a) General. The aeroelastic stability evaluations required under this section include flutter, divergence, control reversal and any undue loss of stability and control as a result of structural deformation. The aeroelastic evaluation must include whirl modes associated with any propeller or rotating device that contributes significant dynamic forces. Compliance with this section must be shown by analyses, wind tunnel tests, ground vibration tests, flight tests, or other means found necessary by the Minister.
(b) Aeroelastic Stability Envelopes. The aeroplane must be designed to be free from aeroelastic instability for all configurations and design conditions within the aeroelastic stability envelopes as follows:
- (1) For normal conditions without failures, malfunctions, or adverse conditions, all combinations of altitudes and speeds encompassed by the V_D/M_D versus altitude envelope enlarged at all points by an increase of 15 percent in equivalent airspeed at both constant Mach number and constant altitude. In addition, a proper margin of stability must exist at all speeds up to V_D/M_D and, there must be no large and rapid reduction in stability as V_D/M_D is approached. The enlarged envelope may be limited to Mach 1.0 when M_D is less than 1.0 at all design altitudes, and
- (2) For the conditions described in 525.629(d) below, for all approved altitudes, any airspeed up to the greater airspeed defined by:
  - (i) The V_D/M_D envelope determined by 525.335(b); or,
  - (ii) An altitude-airspeed envelope defined by a 15 percent increase in equivalent airspeed above V_C at constant altitude, from sea level to the altitude of the intersection of 1.15 V_C with the extension of the constant cruise Mach number line, M_C, then a linear variation in equivalent airspeed to M_C + .05 at the altitude of the lowest V_C/M_C intersection; then at higher altitudes, up to the maximum flight altitude, the boundary defined by a .05 Mach increase in M_C at constant altitude.
(c) Balance Weights. If concentrated balance weights are used, their effectiveness and strength, including supporting structure, must be substantiated.
(d) Failures, malfunctions, and adverse conditions. The failures, malfunctions, and adverse conditions which must be considered in showing compliance with the section are:
- (1) Any critical fuel loading conditions, not shown to be extremely improbable, which may result from mismanagement of fuel.
- (2) Any single failure in any flutter damper system.
- (3) For aeroplanes not approved for operations in icing conditions, the maximum likely ice accumulation expected as a result of an inadvertent encounter.
- (4) Failure of any single element of the structure supporting any engine, independently mounted propeller shaft, large auxiliary power unit, or large externally mounted aerodynamic body (such as an external fuel tank).
- (5) For aeroplanes with engines that have propellers or large rotating devices capable of significant dynamic forces, any single failure of the engine structure that would reduce the rigidity of the rotational axis.
- (6) The absence of aerodynamic or gyroscopic forces resulting from the most adverse combination of feathered propellers or other rotating devices capable of significant dynamic forces. In addition, the effect of a single feathered propeller or rotating device must be coupled with the failures of paragraphs (d)(4) and (d)(5) of this section.
- (7) Any single propeller or rotating device capable of significant dynamic forces rotating at the highest likely overspeed.
- (8) Any damage or failure condition, required or selected for investigation by 525.571. The single structural failures described in paragraphs (d)(4) and (d)(5) of this section need not be considered in showing compliance with this section if:
  - (i) The structural element could not fail due to discreet source damage resulting from the conditions described in 525.571(e), and
  - (ii) A damage tolerance investigation in accordance with 525.571(b) shows that the maximum extent of damage assumed for the purpose of residual strength evaluation does not involve complete failure of the structural element.
- (9) Any damage, failure, or malfunction considered under 525.631, 525.671, 525.672 and 525.1309.
- (10) Any other combination of failures, malfunctions, or adverse conditions not shown to be extremely improbable.
(e) Flight Flutter Testing. Full scale flight flutter tests at speeds up to V_DF/M_DF must be conducted for new type designs and for modifications to a type design unless the modifications have been shown to have an insignificant effect on the aeroelastic stability. These tests must demonstrate that the aeroplane has a proper margin of damping at all speeds up to V_DF/M_DF and that there is no large and rapid reduction in damping as V_DF/M_DF is approached. If a failure, malfunction or adverse condition is simulated during flight test in showing compliance with paragraph (d) of this section, the maximum speed investigated need not exceed V_FC/M_FC if it is shown, by correlation of the flight test data with other test data or analyses, that the aeroplane is free from any aeroelastic instability at all speeds within the altitude-airspeed envelope described in paragraph (b)(2) of this section.

(Change 525-3 (91-11-01))

(Change 525-5 (92-10-30))

525.631 Bird Strike Damage

The empennage structure must be designed to assure capability of continued safe flight and landing of the aeroplane after impact with an 8 pound bird when the velocity of the aeroplane (relative to the bird along the aeroplane's flight path) is equal to V_C at sea level, selected under 525.335(a). Compliance with this section by provision of redundant structure and protected location of control system elements or protective devices such as splitter plates or energy absorbing material is acceptable. Where compliance is shown by analysis, tests, or both, use of data on aeroplanes having similar structural design is acceptable.

Control Surfaces

525.651 Proof of Strength

(a) Limit load tests of control surfaces are required. These tests must include the horn or fitting to which the control system is attached.
(b) Compliance with the special factors requirements of 525.619 through 525.625 and 525.657 for control surface hinges must be shown by analysis or individual load tests.

525.655 Installation

(a) Movable tail surfaces must be installed so that there is no interference between any surfaces when one is held in its extreme position and the others are operated through their full angular movement.
(b) If an adjustable stabiliser is used, it must have stops that will limit its range of travel to the maximum for which the aeroplane is shown to meet the trim requirements of 525.161.

525.657 Hinges

(a) For control surface hinges, including ball, roller, and self-lubricated bearing hinges, the approved rating of the bearing may not be exceeded. For non-standard bearing hinge configurations, the rating must be established on the basis of experience or tests and, in the absence of a rational investigation, a factor of safety of not less than 6.67 must be used with respect to the ultimate bearing strength of the softest material used as a bearing.
(b) Hinges must have enough strength and rigidity for loads parallel to the hinge line.

Control Systems

525.671 General

(a) Each control and control system must operate with the ease, smoothness, and positiveness appropriate to its function.
(b) Each element of each flight control system must be designed, or distinctively and permanently marked, to minimise the probability of incorrect assembly that could result in the malfunctioning of the system.
(c) The aeroplane must be shown by analysis, test, or both, to be capable of continued safe flight and landing after any of the following failures or jamming in the flight control system and surfaces (including trim, lift, drag, and feel systems) within the normal flight envelope, without requiring exceptional piloting skill or strength. Probable malfunctions must have only minor effects on control system operation and must be capable of being readily counteracted by the pilot.
- (1) Any single failure, excluding jamming (for example, disconnection or failure of mechanical elements, or structural failure of hydraulic components, such as actuators, control spool housing, and valves).
- (2) Any combination of failures not shown to be extremely improbable, excluding jamming (for example, dual electrical or hydraulic system failures, or any single failure in combination with any probable hydraulic or electrical failure).
- (3) Any jam in a control position normally encountered during take-off, climb, cruise, normal turns, descent, and landing unless the jam is shown to be extremely improbable, or can be alleviated. A runaway of a flight control to an adverse position and jam must be accounted for if such runaway and subsequent jamming is not extremely improbable.
(d) The aeroplane must be designed so that it is controllable if all engines fail. Compliance with this requirement may be shown by analysis where that method has been shown to be reliable.

525.672 Stability Augmentation and Automatic and Power-Operated Systems

If the functioning of stability augmentation or other automatic or power-operated systems is necessary to show compliance with the flight characteristics requirements of this chapter, such systems must comply with 525.671 and the following:

(a) A warning which is clearly distinguishable to the pilot under expected flight conditions without requiring his attention must be provided for any failure in the stability augmentation system or in any other automatic or power-operated system which could result in an unsafe condition if the pilot were not aware of the failure. Warning systems must not activate the control systems.
(b) The design of the stability augmentation system or of any other automatic or power-operated system must permit initial counteraction of failures of the type specified in 525.671(c) without requiring exceptional pilot skill or strength, by either the deactivation of the system, or a failed portion thereof, or by overriding the failure by movement of the flight controls in the normal sense.
(c) It must be shown that after any single failure of the stability augmentation system or any other automatic or power-operated system:
- (1) The aeroplane is safely controllable when the failure or malfunction occurs at any speed or altitude within the approved operating limitations that is critical for the type of failure being considered;
- (2) The controllability and manoeuvrability requirements of this chapter are met within a practical operational flight envelope (for example, speed, altitude, normal acceleration, and aeroplane configurations) which is described in the Aeroplane Flight Manual; and
- (3) The trim, stability, and stall characteristics are not impaired below a level needed to permit continued flight and landing.

525.675 Stops

(a) Each control system must have stops that positively limit the range of motion of each movable aerodynamic surface controlled by the system.
(b) Each stop must be located so that wear, slackness, or take-up adjustments will not adversely affect the control characteristics of the aeroplane because of a change in the range of surface travel.
(c) Each stop must be able to withstand any loads corresponding to the design conditions for the control system.

525.677 Trim Systems

(a) Trim controls shall be designed to prevent inadvertent or abrupt operation and to operate in the plane, and with the sense of motion, of the aeroplane.
(amended 2005/06/03)
(b) There shall be means adjacent to the trim control to indicate the direction of the control movement relative to the aeroplane motion. In addition, there must be clearly visible means to indicate the position of the trim device with respect to the range of adjustment. The indicator shall be clearly marked with the range within which it has been demonstrated that take-off is safe for all centre of gravity positions approved for take-off.
(amended 2005/06/03)
(c) Trim control systems shall be designed to prevent creeping in flight. Trim tab controls shall be irreversible unless the tab is appropriately balanced and shown to be free from flutter.
(amended 2005/06/03)
(d) If an irreversible tab control system is used, the part from the tab to the attachment of the irreversible unit to the aeroplane structure shall consist of a rigid connection.
(amended 2005/06/03)

525.679 Control System Gust Locks

(a) There must be a device to prevent damage to the control surfaces (including tabs), and to the control system, from gusts striking the aeroplane while it is on the ground or water. If the device, when engaged, prevents normal operation of the control surface by the pilot, it must:
- (1) Automatically disengage when the pilot operates the primary flight controls in a normal manner; or
- (2) Limit the operation of the aeroplane so that the pilot receives unmistakable warning at the start of take-off.
(b) The device must have means to preclude the possibility of it becoming inadvertently engaged in flight.

525.681 Limit Load Static Tests

(a) Compliance with the limit load requirements of this chapter must be shown by tests in which:
- (1) The direction of the test loads produces the most severe loading in the control system; and
- (2) Each fitting, pulley, and bracket used in attaching the system to the main structure is included.
(b) Compliance must be shown (by analyses or individual load tests) with the special factor requirements for control system joints subject to angular motion.

525.683 Operation Tests
(effective 2019/11/01)

(a) It must be shown by operation tests that when portions of the control system subject to pilot effort loads are loaded to 80 percent of the limit load specified for the system and the powered portions of the control system are loaded to the maximum load expected in normal operation, the system is free from:
- (1) Jamming;
- (2) Excessive friction; and
- (3) Excessive deflection.
(b) It must be shown by analysis and, where necessary, by tests, that in the presence of deflections of the aeroplane structure due to the separate application of pitch, roll, and yaw limit manoeuver loads, the control system, when loaded to obtain these limit loads and operated within its operational range of deflections, can be exercised about all control axes and remain free from:
- (1) Jamming;
- (2) Excessive friction;
- (3) Disconnection; and
- (4) Any form of permanent damage.
(c) It must be shown that under vibration loads in the normal flight and ground operating conditions, no hazard can result from interference or contact with adjacent elements.

525.685 Control System Details

(a) Each detail of each control system must be designed and installed to prevent jamming, chafing, and interference from cargo, passengers, loose objects, or the freezing of moisture.
(b) There must be means in the cockpit to prevent the entry of foreign objects into places where they would jam the system.
(c) There must be means to prevent the slapping of cables or tubes against other parts.
(d) Sections 525.689 and 525.693 apply to cable systems and joints.

525.689 Cable Systems

(a) Each cable, cable fitting, turnbuckle, splice, and pulley must be approved. In addition:
- (1) No cable smaller than 1/8 inch in diameter may be used in the aileron, elevator, or rudder systems; and
- (2) Each cable system must be designed so that there will be no hazardous change in cable tension throughout the range of travel under operating conditions and temperature variations.
(b) Each kind and size of pulley must correspond to the cable with which it is used. Pulleys and sprockets must have closely fitted guards to prevent the cables and chains from being displaced or fouled. Each pulley must lie in the plane passing through the cable so that the cable does not rub against the pulley flange.
(c) Fairleads must be installed so that they do not cause a change in cable direction of more than three degrees.
(d) Clevis pins subject to load or motion and retained only by cotter pins may not be used in the control system.
(e) Turnbuckles must be attached to parts having angular motion in a manner that will positively prevent binding throughout the range of travel.
(f) There must be provisions for visual inspection of fairleads, pulleys, terminals, and turnbuckles.

525.693 Joints

Control system joints (in push-pull systems) that are subject to angular motion, except those in ball and roller bearing systems, must have a special factor of safety of not less than 3.33 with respect to the ultimate bearing strength of the softest material used as a bearing. This factor may be reduced to 2.0 for joints in cable control systems. For ball or roller bearings, the approved ratings, may not be exceeded.

(Change 525-3 (91-11-01))

525.697 Lift and Drag Devices, Controls

(a) Each lift device control must be designed so that the pilots can place the device in any take-off, en route, approach, or landing position established under 525.101(d). Lift and drag devices must maintain the selected positions, except for movement produced by an automatic positioning or load limiting device, without further attention by the pilots.
(b) Each lift and drag device control must be designed and located to make inadvertent operation improbable. Lift and drag devices intended for ground operation only must have means to prevent operation of their controls in flight unless it is demonstrated that operation of the control is not hazardous.

FAR:

(b) Each lift and drag device control must be designed and located to make inadvertent operation improbable. Lift and drag devices intended for ground operation only must have means to prevent the inadvertent operation of their controls in flight if that operation could be hazardous.

(c) The rate of motion of the surface in response to the operation of the control and the characteristics of the automatic positioning or load limiting device must give satisfactory flight and performance characteristics under steady or changing conditions of airspeed, engine power, and aeroplane attitude.
(d) The lift device control must be designed to retract the surfaces from the fully extended position, during steady flight at maximum continuous engine power, and at any speed below V_F+ 9.0 (knots).

525.699 Lift and Drag Device Indicator

(a) There must be means to indicate to the pilots the position of each lift or drag device having a separate control in the cockpit to adjust its position. In addition, an indication of unsymmetrical operation or other malfunction in the lift or drag service systems must be provided when such indication is necessary to enable the pilots to prevent or counteract an unsafe flight or ground condition, considering the effects on flight characteristics and performance.
(b) There must be means to indicate to the pilots the take-off, en route approach, and landing lift device positions.
(c) If any extension of the lift and drag devices beyond the landing position is possible, the control must be clearly marked to identify this range of extension.
(d) Lift and drag devices (other than flaps and leading edge devices) must have a device to warn the pilot that the control is operated, unless it is demonstrated that operation of the control is not hazardous.

FAR:

No equivalent text.

525.701 Flap and Slat Interconnection

(a) Unless the aeroplane has safe flight characteristics with the flaps or slats retracted on one side and extended on the other, the motion of flaps or slats on opposite sides of the plane of symmetry must be synchronised by a mechanical interconnection or approved equivalent means.
(b) If a wing flap or slat interconnection or equivalent means is used, it must be designed to account for the applicable unsymmetrical loads, including those resulting from flight with the engines on one side of the plane of symmetry inoperative and the remaining engines at take-off power.
(c) For aeroplanes with flaps or slats that are not subjected to slipstream conditions, the structure must be designed for the loads imposed when the wing flaps or slats on one side are carrying the most severe load occurring in the prescribed symmetrical conditions and those on the other side are carrying not more than 80 percent of that load.
(d) The flap interconnection must be designed for the loads resulting when the flap or slats surfaces on one side of the plane of symmetry are jammed and immovable while the surface on the other side are free to move and the full power of the surface actuating system is applied.

(Change 525-3 (91-11-01))

525.703 Take-off Warning System

A take-off warning system must be installed and must meet the following requirements:

(a) The system must provide to the pilots an aural warning that is automatically activated during the initial portion of the take-off roll if the aeroplane is in a configuration, including any of the following, that would not allow a safe take-off:
- (1) The wing flaps or leading edge devices are not within the approved range of take-off positions.
- (2) Wing spoilers (except lateral control spoilers meeting the requirements of 525.671), speed brakes, or longitudinal trim devices are in a position that would not allow a safe take-off.
(b) The warning required by paragraph (a) of this section must continue until:
- (1) The configuration is changed to allow a safe take-off;
- (2) Action is taken by the pilot to terminate the take-off roll;
- (3) The aeroplane is rotated for take-off; or
- (4) The warning is manually deactivated by the pilot.
(c) The means used to activate the system must function properly throughout the ranges of take-off weights, altitudes, and temperatures for which certification is requested.

Landing Gear

525.721 General
(effective 2019/11/01)

(a) The landing gear system must be designed so that when it fails due to overloads during take-off and landing, the failure mode is not likely to cause spillage of enough fuel to constitute a fire hazard. The overloads must be assumed to act in the upward and aft directions in combination with side loads acting inboard and outboard. In the absence of a more rational analysis, the side loads must be assumed to be up to 20 percent of the vertical load or 20 percent of the drag load, whichever is greater.
(b) The aeroplane must be designed to avoid any rupture leading to the spillage of enough fuel to constitute a fire hazard as a result of a wheels-up landing on a paved runway, under the following minor crash landing conditions:
- (1) Impact at 5 feet-per-second vertical velocity, with the aeroplane under control, at Maximum Design Landing Weight:
  - (i) With the landing gear fully retracted; and
  - (ii) With any one or more landing gear legs not extended.
- (2) Sliding on the ground, with:
  - (i) The landing gear fully retracted and with up to a 20° yaw angle; and
  - (ii) Any one or more landing gear legs not extended and with 0° yaw angle.
(c) For configurations where the engine nacelle is likely to come into contact with the ground, the engine pylon or engine mounting must be designed so that when it fails due to overloads (assuming the overloads to act predominantly in the upward direction and separately, predominantly in the aft direction), the failure mode is not likely to cause the spillage of enough fuel to constitute a fire hazard.

525.723 Shock Absorption Tests

(a) The analytical representation of the landing gear dynamic characteristics that is used in determining the landing loads shall be validated by energy absorption tests. A range of tests shall be conducted to ensure that the analytical representation is valid for the design conditions specified in section 525.473.
(amended 2001/10/01)
- (1) The configurations subjected to energy absorption tests at limit design conditions shall include at least the design landing weight or the design takeoff weight, whichever produces the greater value of landing impact energy.
- (2) The test attitude of the landing gear unit and the application of appropriate drag loads during the test shall simulate the aeroplane landing conditions in a manner consistent with the development of rational or conservative limit loads.
(b) The landing gear may not fail in a test, demonstrating its reserve energy absorption capacity, simulating a descent velocity of 12 f.p.s. at design landing weight, assuming aeroplane lift not greater than aeroplane weight acting during the landing impact.
(amended 2001/10/01)
(c) In lieu of the tests prescribed in this section, changes in previously approved design weights and minor changes in design may be substantiated by analyses based on previous tests conducted on the same basic landing gear system that has similar energy absorption characteristics.
(amended 2001/10/01; no previous version)

(Change 525-3 (91-11-01)

525.725 (Reserved)

(amended 2001/10/01)

525.727 (Reserved)

(amended 2001/10/01)

525.729 Retracting Mechanism

(a) General. For aeroplanes with retractable landing gear, the following apply:
- (1) The landing gear retracting mechanism, wheel well doors, and supporting structure, must be designed for:
  - (i) The loads occurring in the flight conditions when the gear is in the retracted position;
  - (ii) The combination of friction loads, inertia loads, brake torque loads, air loads, and gyroscopic loads resulting from the wheels rotating at a peripheral speed equal to 1.23 V_SR (with the wing flaps in take off position at design take-off weight), occurring during retraction and extension at any airspeed up to 1.5 V_SR1 (with the wing flaps in the approach position at design landing weight), and
    (effective 2014/11/30)
  - (iii) Any load factor up to those specified in 525.345(a) for the wing flaps extended condition.
    (effective 2014/11/30)
- (2) Unless there are other means to decelerate the aeroplane in flight at this speed, the landing gear, the retracting mechanism, and the aeroplane structure (including wheel well doors) must be designed to withstand the flight loads occurring with the landing gear in the extended position at any speed up to 0.67 V_C.
- (3) Landing gear doors, their operating mechanism, and their supporting structures must be designed for the yawing manoeuvres prescribed for the aeroplane in addition to the conditions of airspeed and load factor prescribed in subparagraphs (1) and (2) of this paragraph.
(b) Landing gear lock. There must be positive means to keep the landing gear extended in flight and on the ground. There must be positive means to keep the landing gear and doors in the correct retracted position in flight, unless it can be shown that lowering of the landing gear or doors, or flight with the landing gear or doors extended, at any speed, is not hazardous.
(effective 2014/11/30)
(c) Emergency operation. There must be an emergency means for extending the landing gear in the event of:
- (1) Any reasonably probable failure in the normal retraction system; or
- (2) The failure of any single source of hydraulic, electric, or equivalent energy supply.
(d) Operation test. The proper functioning of the retracting mechanism must be shown by operation tests.
(e) Position indicator and warning device. If a retractable landing gear is used, there must be a landing gear position indicator easily visible to the pilot or to the appropriate flight crew members (as well as necessary devices to actuate the indicator) to indicate without ambiguity that the retractable units and their associated doors are secured in the extended (or retracted) position. This means must be designed as follows:
(effective 2014/11/30)
- (1) If switches are used, they must be located and coupled to the landing gear mechanical systems in a manner that prevents an erroneous indication of "down and locked" if the landing gear is not in a fully extended position, or of "up and locked" if the landing gear is not in the fully retracted position. The switches may be located where they are operated by the actual landing gear locking latch or device.
- (2) The flight crew must be given an aural warning that functions continuously, or is periodically repeated, if a landing is attempted when the landing gear is not locked down.
- (3) The warning must be given in sufficient time to allow the landing gear to be locked down or a go-around to be made.
- (4) There must not be a manual shut-off means readily available to the flight crew for the warning required by paragraph (e)(2) of this section such that it could be operated instinctively, inadvertently, or by habitual reflexive action.
- (5) The system used to generate the aural warning must be designed to minimize false or inappropriate alerts.
  (effective 2014/11/30)
- (6) Failures of systems used to inhibit the landing gear aural warning, that would prevent the warning system from operating, must be improbable.
- (7) A flight crew member alert must be provided whenever the landing gear position is not consistent with the landing gear selector lever position.
  (effective 2014/11/30)
(f) Protection of equipment on landing gear and in wheel wells. Equipment that is essential to the safe operation of the aeroplane and that is located on the landing gear and in wheel wells must be protected from the damaging effects of:
(effective 2014/11/30)
- (1) a bursting tire;
  (effective 2014/11/30)
- (2) a loose tire tread, unless it is shown that a loose tire tread cannot cause damage; or
- (3) Possible wheel brake temperatures.
  (effective 2014/11/30)

(Change 525-3 (91-11-01))

(Change 525-4 (92-08-01))

525.731 Wheels

(a) Each main and nose wheel shall be approved.
(amended 2003/11/10)
(b) The maximum static load rating of each wheel may not be less than the corresponding static ground reaction with:
- (1) Design maximum weight; and
- (2) Critical centre of gravity.
(c) The maximum limit load rating of each wheel shall equal or exceed the maximum radial limit load determined under the applicable ground load requirements of this chapter.
(amended 2003/11/10)
(d) Overpressure burst prevention. Means shall be provided in each wheel to prevent wheel failure and tire burst that may result from excessive pressurization of the wheel and tire assembly.
(amended 2003/11/10; no previous version)
(e) Braked wheels. Each braked wheel shall meet the applicable requirements of 525.735.
(amended 2003/11/10; no previous version)

(Change 525-3 (91-11-01))

525.733 Tires

(a) When a landing gear axle is fitted with a single wheel and tire assembly, the wheel must be fitted with a suitable tire of proper fit with a speed rating approved by the Minister that is not exceeded under critical conditions and with a load rating approved by the Minister that is not exceeded under:
- (1) The loads on the main wheel tire, corresponding to the most critical combination of aeroplane weight (up to the maximum weight), and centre of gravity position; and
- (2) The loads corresponding to the ground reactions in paragraph (b) of this section, on the nose wheel tire, except as provided in paragraphs (b)(2) and (b)(3) of this section.
(b) The applicable ground reactions for nose wheel tires are as follows:
- (1) The static ground reaction for the tire corresponding to the most critical combination of aeroplane weight (up to maximum ramp weight) and centre of gravity position with a force of 1.0g acting downward at the centre of gravity. This load may not exceed the load rating of the tire.
- (2) The ground reaction of the tire corresponding to the most critical combination of aeroplane weight (up to maximum landing weight) and centre of gravity position combined with forces of 1.0g downward and 0.31g forward acting at the centre of gravity. The reactions in this case must be distributed to the nose and main wheels by the principles of statics with a drag reaction equal to 0.31 times the vertical load at each wheel with brakes capable of producing this ground reaction. This nose tire load may not exceed 1.5 times the load rating of the tire.
- (3) The ground reaction of the tire corresponding to the most critical combination of aeroplane weight (up to maximum ramp weight) and centre of gravity position combined with forces of1.0g downward and 0.20g forward acting at the centre of gravity. The reactions in this case must be distributed to the nose and main wheels by the principles of statics with a drag reaction equal to 0.20 times the vertical load at each wheel with brakes capable of producing this ground reaction. This nose tire load may not exceed 1.5 times the load rating of the tire.
(c) When a landing gear axle is fitted with more than one wheel and tire assembly, such as dual or dual-tandem, each wheel must be fitted with a suitable tire of proper fit with a speed rating approved by the Minister that is not exceeded under critical conditions, and with a load rating approved by the Minister that is not exceeded by:
- (1) The loads on the main wheel tire, corresponding to the most critical combination of aeroplane weight (up to maximum weight) and centre of gravity position, when multiplied by a factor of 1.07; and
- (2) Loads specified in paragraphs (a)(2), (b)(1), (b)(2), and (b)(3) of this section on each nose wheel tire.
(d) Each tire installed on a retractable landing gear system must, at the maximum size of the tire type expected in service, have a clearance to surrounding structure and systems that is adequate to prevent unintended contact between the tire and any part of the structure or systems.
(e) For an aeroplane with a maximum certified take-off weight of more than 75,000 pounds, tires mounted on braked wheels must be inflated with dry nitrogen or other gases shown to be inert so that the gas mixture in the tire does not contain oxygen in excess of 5 percent by volume, unless it can be shown that the tire liner material will not produce a volatile gas when heated or that means are provided to prevent tire temperatures from reaching unsafe levels.

(Change 525-3 (91-11-01))

(Change 525-6 (93-12-30))

525.735 Brakes and Braking Systems

(amended 2003/11/10)

(a) Approval. Each assembly consisting of a wheel(s) and brake(s) shall be approved.
(amended 2003/11/10)
(b) Brake system capability. The brake system, associated systems and components shall be designed and constructed so that:
(amended 2003/11/10)
- (1) If any electrical, pneumatic, hydraulic or mechanical connecting or transmitting element fails, or if any single source of hydraulic or other brake operating energy supply is lost, it is possible to bring the aeroplane to rest with a braked roll stopping distance of not more than two times that obtained in determining the landing distance as prescribed in section 525.125.
  (amended 2003/11/10)
- (2) Fluid lost from a brake hydraulic system following a failure in, or in the vicinity of, the brakes is insufficient to cause or support a hazardous fire on the ground or in flight.
  (amended 2003/11/10)
(c) Brake controls. The Brake controls shall be designed and constructed so that:
(amended 2003/11/10)
- (1) Excessive control force is not required for their operation.
  (amended 2003/11/10)
- (2) If an automatic braking system is installed, means are provided to:
  (amended 2003/11/10)
  - (i) Arm and disarm the system, and
  - (ii) Allow the pilot(s) to override the system by use of manual braking.
(d) Parking brake. The aeroplane shall have a parking brake control that, when selected on, will, without further attention, prevent the aeroplane from rolling on a dry and level paved runway when the most adverse combination of maximum thrust on one engine and up to maximum ground idle thrust on any, or all, other engine(s) is applied. The control shall be suitably located or be adequately protected to prevent inadvertent operation. There shall be indication in the cockpit when the parking brake is not fully released.
(amended 2003/11/10)
(e) Antiskid system. If an antiskid system is installed:
(amended 2003/11/10)
- (1) It shall operate satisfactorily over the range of expected runway conditions, without external adjustment.
- (2) It shall, at all times, have priority over the automatic braking system, if installed.
(f) Kinetic energy capacity.
- (1) Design landing stop. The design landing stop is an operational landing stop at maximum landing weight. The design landing stop brake kinetic energy absorption requirement of each wheel, brake, and tire assembly shall be determined. It shall be substantiated by dynamometer testing that the wheel, brake, and tire assembly is capable of absorbing not less than this level of kinetic energy throughout the defined wear range of the brake. The energy absorption rate derived from the aeroplane manufacturer's braking requirements shall be achieved. The mean deceleration shall not be less than 10 fps².
  (amended 2003/11/10)
- (2) Maximum kinetic energy accelerate-stop. The maximum kinetic energy accelerate-stop is a rejected takeoff for the most critical combination of aeroplane takeoff weight and speed. The accelerate-stop brake kinetic energy absorption requirement of each wheel, brake, and tire assembly shall be determined. It shall be substantiated by dynamometer testing that the wheel, brake, and tire assembly is capable of absorbing not less than this level of kinetic energy throughout the defined wear range of the brake. The energy absorption rate derived from the aeroplane manufacturer's braking requirements shall be achieved. The mean deceleration shall not be less than 6 fps².
  (amended 2003/11/10)
- (3) Most severe landing stop. The most severe landing stop is a stop at the most critical combination of aeroplane landing weight and speed. The most severe landing stop brake kinetic energy absorption requirement of each wheel, brake, and tire assembly shall be determined. It shall be substantiated by dynamometer testing that, at the declared fully worn limit(s) of the brake heat sink, the wheel, brake and tire assembly is capable of absorbing not less than this level of kinetic energy. The most severe landing stop need not be considered for extremely improbable failure conditions or if the maximum kinetic energy accelerate-stop energy is more severe.
  (amended 2003/11/10)
(g) Brake condition after high kinetic energy dynamometer stop(s). Following the high kinetic energy stop demonstration(s) required by subsection (f) of this section, with the parking brake promptly and fully applied for at least 3 minutes, it shall be demonstrated that for at least 5 minutes from application of the parking brake, no condition occurs (or has occurred during the stop), including fire associated with the tire or wheel and brake assembly, that could prejudice the safe and complete evacuation of the aeroplane.
(amended 2003/11/10)
(h) Stored energy systems. An indication to the flight crew of the usable stored energy shall be provided if a stored energy system is used to demonstrate compliance with paragraph (b)(1) of this section. The available stored energy shall be sufficient for:
(amended 2003/11/10)
- (1) At least 6 full applications of the brakes when an antiskid system is not operating; and
- (2) Bringing the aeroplane to a complete stop when an antiskid system is operating, under all runway surface conditions for which the aeroplane is certificated.
(i) Brake wear indicators. Means shall be provided for each brake assembly to indicate when the heat sink is worn to the permissible limit. The means shall be reliable and readily visible.
(amended 2003/11/10; no previous version)
(j) Overtemperature burst prevention. Means shall be provided in each braked wheel to prevent a wheel failure, a tire burst, or both, that may result from elevated brake temperatures. Additionally, all wheels shall meet the requirements of 525.731(d).
(amended 2003/11/10; no previous version)
(k) Compatibility. Compatibility of the wheel and brake assemblies with the aeroplane and its systems shall be substantiated.
(amended 2003/11/10; no previous version)

525.737 Skis

Each ski must be approved. The maximum limit load rating of each ski must equal or exceed the maximum limit load determined under the applicable ground load requirements of this chapter.

Floats and Hulls

525.751 Main Float Buoyancy

Each main float must have:

(a) A buoyancy of 80 percent in excess of that required to support the maximum weight of the seaplane or amphibian in fresh water; and
(b) Not less than five watertight compartments approximately equal in volume.

525.753 Main Float Design

Each main float must be approved and must meet the requirements of 525.521.

525.755 Hulls

(a) Each hull must have enough watertight compartments so that, with any two adjacent compartments flooded, the buoyancy of the hull and auxiliary floats (and wheel tires, if used) provides a margin of positive stability great enough to minimise the probability of capsizing in rough, fresh water.
(b) Bulkheads with watertight doors may be used for communication between compartments.

Personnel and Cargo Accommodations

525.771 Pilot Compartment

(a) Each pilot compartment and its equipment must allow the minimum flight crew (established under 525.1523) to perform their duties without unreasonable concentration or fatigue.
(b) The primary controls listed in 525.779(a), excluding cables and control rods, must be located with respect to the propellers so that no member of the minimum flight crew (established under 525.1523), or part of the controls, lies in the region between the plane of rotation of any inboard propeller and the surface generated by a line passing through the centre of the propeller hub making an angle of five degrees forward or aft of the plane of rotation of the propeller.
(c) If provision is made for a second pilot, the aeroplane must be controllable with equal safety from either pilot seat.
(d) The pilot compartment must be constructed so that, when flying in rain or snow, it will not leak in a manner that will distract the crew or harm the structure.
(e) Vibration and noise characteristics of cockpit equipment may not interfere with safe operation of the aeroplane.

525.772 Pilot Compartment Doors

For an aeroplane that has a lockable door installed between the pilot compartment and the passenger compartment:

(a) If the aeroplane has a maximum passenger seating configuration of 20 seats or more, the emergency exit configuration must be designed so that neither crew members nor passengers require use of the flight deck door in order to reach the emergency exits provided for them;
(b) Means must be provided to enable flight crew members to directly enter the passenger compartment from the pilot compartment if the flight deck door becomes jammed; and
(c) Emergency means must be provided to enable a crew member to enter the pilot compartment in the event that the flight crew becomes incapacitated.

(Change 525-3 (91-11-01))

(Change 525-8.1 (2002-03-21))

525.773 Pilot Compartment View

(a) Non-precipitation conditions. For non-precipitation conditions, the following apply:
- (1) Each pilot compartment must be arranged to give the pilots a sufficiently extensive, clear, and undistorted view, to enable them to safely perform any manoeuvres within the operating limitations of the aeroplane, including taxiing, take-off, approach, and landing.
- (2) Each pilot compartment must be free of glare and reflection that could interfere with the normal duties of the minimum flight crew (established under 525.1523).This must be shown in day and night flight tests under non-precipitation conditions.
(b) Precipitation conditions. For precipitation conditions, the following apply:
- (1) The aeroplane shall have a means to maintain a clear portion of the windshield during precipitation conditions, sufficient for both pilots to have a sufficiently extensive view along the flight path in normal flight attitudes of the aeroplane. This means shall be designed to function, without continuous attention on the part of the flight crew, in:
  (amended 2008/10/30)
  - (i) Heavy rain at speeds up to 1.5 V_SR1 with lift and drag devices retracted; and
    (amended 2003/11/10)
  - (ii) The icing conditions specified in Appendix C of this chapter and the following icing conditions specified in Appendix O of this chapter, if certification for flight in icing conditions is sought:
    (effective 2021/04/08)
    - (A) For aeroplanes certificated in accordance with 525.1420(a)(1), the icing conditions that the aeroplane is certified to safely exit following detection.
      (effective 2021/04/08)
    - (B) For aeroplanes certificated in accordance with 525.1420(a)(2), the icing conditions that the aeroplane is certified to safely operate in and the icing conditions that the aeroplane is certified to safely exit following detection.
      (effective 2021/04/08)
    - (C) For aeroplanes certificated in accordance with 525.1420(a)(3) and for aeroplanes not subject to 525.1420, all icing conditions
      (effective 2021/04/08)
  - (2) No single failure of the systems used to provide the view required by (b)(1) of this section must cause the loss of that view by both pilots in the specified precipitation conditions.
    (effective 2014/11/30)
  - (3) The first pilot must have a window that:
    (effective 2014/11/30)
    - (i) is openable under the conditions prescribed in (b)(1) of this section when the cabin is not pressurized;
      (effective 2014/11/30)
    - (ii) provides the view specified in (b)(1) of this section; and
      (effective 2014/11/30)
    - (iii) provides sufficient protection from the elements against impairment of the pilot's vision.
      (effective 2014/11/30)
  - (4) The openable window specified in (b)(3) of this section need not be provided if it is shown that an area of the transparent surface will remain sufficiently clear for at least one pilot to land the aeroplane safely in the event of:
    (effective 2014/11/30)
    - (i) any system failure or combination of failures which is not extremely improbable, in accordance with 525.1309, under the precipitation conditions specified in (b)(1) of this section; or
    - (ii) an encounter with severe hail, birds or insects.
- (c) Internal windshield and window fogging. The aeroplane must have a means to prevent fogging of the internal portions of the windshield and window panels over an area which would provide the visibility specified in paragraph (a) of this section under all internal and external ambient conditions, including precipitation conditions, in which the aeroplane is intended to be operated.
- (d) Fixed markers or other guides must be installed at each pilot station to enable the pilots to position themselves in their seats for an optimum combination of outside visibility and instrument scan. If lighted markers or guides are used they must comply with the requirements specified in 525.1381.
- (e) Vision systems with transparent displays. A vision system with a transparent display surface located in the pilot’s outside field of view, such as a head-up display, head mounted display, or other equivalent display, must meet the following requirements in non-precipitation and precipitation conditions:
  (effective 2019/08/15)
  - (1) While the vision system display is in operation, it must compensate for interference with the pilot’s outside field of view such that the combination of what is visible in the display and what remains visible through and around it, enables the pilot to perform the manoeuvres and normal duties of paragraph (a) of this section.
  - (2) The pilot’s view of the external scene may not be distorted by the transparent display surface or by the vision system imagery. When the vision system displays imagery or any symbology that is referenced to the imagery and outside scene topography, including attitude symbology, flight path vector, and flight path angle reference cue, that imagery and symbology must be aligned with, and scaled to, the external scene.
  - (3) The vision system must provide a means to allow the pilot using the display to immediately deactivate and reactivate the vision system imagery, on demand, without removing the pilot’s hands from the primary flight controls or thrust controls.
  - (4) When the vision system is not in operation it may not restrict the pilot from performing the manoeuvres specified in paragraph (a)(1) of this section or the pilot compartment from meeting the provisions of paragraph (a)(2) of this section.

(Change 525-3 (91-11-01))

525.775 Windshields and Windows

(a) Internal panes must be made of non-splintering material.
(b) Windshield panes directly in front of the pilots in the normal conduct of their duties, and the supporting structures for these panes, must withstand, without penetration, the impact of a four-pound bird when the velocity of the aeroplane (relative to the bird along the aeroplane's flight path) is equal to the value of V_C, at sea level, selected under 525.335(a).
(c) Unless it can be shown by analysis or tests that the probability of occurrence of a critical windshield fragmentation condition is of a low order, the aeroplane must have a means to minimise the danger to the pilots from flying windshield fragments due to bird impact. This must be shown for each transparent pane in the cockpit that:
- (1) Appears in the front view of the aeroplane;
- (2) Is inclined 15 degrees or more to the longitudinal axis of the aeroplane; and
- (3) Has any part of the pane located where its fragmentation will constitute a hazard to the pilots.
(d) The design of windshields and windows in pressurised aeroplanes must be based on factors peculiar to high altitude operation, including the effects of continuous and cyclic pressurisation loadings, the inherent characteristics of the material used, and the effects of temperatures and temperature differentials. The windshield and window panels must be capable of withstanding the maximum cabin pressure differential loads combined with critical aerodynamic pressure and temperature effects after any single failure in the installation or associated systems. It may be assumed that, after a single failure that is obvious to the flight crew (established under 525.1523), the cabin pressure differential is reduced from the maximum, in accordance with appropriate operating limitations, to allow continued safe flight of the aeroplane with a cabin pressure altitude of not more than 15,000 feet.
(e) The windshield panels in front of the pilots must be arranged so that, assuming the loss of vision through any one panel, one or more panels remain available for use by a pilot seated at a pilot station to permit continued safe flight and landing.

525.777 Cockpit Controls

(a) Each cockpit control must be located to provide convenient operation and to prevent confusion and inadvertent operation.
(b) The direction of movement of cockpit controls must meet the requirements of 525.779. Wherever practicable, the sense of motion involved in the operation of other controls must correspond to the sense of the effect of the operation upon the aeroplane or upon the part operated. Controls of a variable nature using a rotary motion must move clockwise from the off position, through an increasing range, to the full on position.
(c) The controls must be located and arranged, with respect to the pilots' seats, so that there is full and unrestricted movement of each control without interference from the cockpit structure or the clothing of the minimum flight crew (established under 525.1523) when any member of this flight crew, from 5'2" to 6'3" in height, is seated with the seat belt and shoulder harness (if provided) fastened.
(d) Identical powerplant controls for each engine must be located to prevent confusion as to the engines they control.
(e) Wing flap controls and other auxiliary lift device controls must be located on top of the pedestal, aft of the throttles, centrally or to the right of the pedestal centreline, and not less than 10 inches aft of the landing gear control.
(f) The landing gear control must be located forward of the throttles and must be operable by each pilot when seated with seat belt and shoulder harness (if provided) fastened.
(g) Control knobs must be shaped in accordance with 525.781. In addition, the knobs must be of the same colour, and this colour must contrast with the colour of control knobs for other purposes and the surrounding cockpit.
(h) If a flight engineer is required as part of the minimum flight crew (established under 525.1523), the aeroplane must have a flight engineer station located and arranged so that the flight crew members can perform their functions efficiently and without interfering with each other.

525.779 Motion and Effect of Cockpit Controls

Cockpit controls must be designed so that they operate in accordance with the following movement and actuation:

(a) Aerodynamic controls:
- (1) Primary.

Controls	Motion And Effect
Aileron Elevator Rudder	Right (clockwise) for right wing down. Rearward for nose up. Right pedal forward for nose right.

(1) Secondary.

Controls	Motion And Effect
Flaps (or auxiliary lift devices). Trim tabs (or equivalent).	Forward for flaps up, rearward for flaps down. Rotate to produce similar rotation of the aeroplane about an axis parallel to the axis of the control.

(b) Powerplant and auxiliary controls:
- (1) Powerplant.

Controls	Motion And Effect
Power or thrust Propellers Mixture Carburettor air heat Supercharger	Forward to increase forward thrust and rearward to increase rearward thrust. Forward to increase rpm. Forward of upward for rich. Forward of upward for cold. Forward of upward for low blower. for turbosuperchargers, forward, upward, or clockwise, to increase pressure.

(2) Auxiliary.

Controls	Motion And Effect
Landing Gear	Down to extend.

(Change 525-3 (91-11-01))

525.781 Cockpit Control Knob Shape

Cockpit control knobs must conform to the general shapes (but not necessarily the exact sizes or specific proportions) in the following figure:

(Change 525-3 (91-11-01))

525.783 Fuselage Doors
(amended 2007/03/08)

(a) General. This section applies to fuselage doors, which includes all doors, hatches, openable windows, access panels, covers, etc., on the exterior of the fuselage that do not require the use of tools to open or close. This also applies to each door or hatch through a pressure bulkhead, including any bulkhead that is specifically designed to function as a secondary bulkhead under the prescribed failure conditions of AWM Chapter 525. These doors shall meet the requirements of this section, taking into account both pressurized and unpressurized flight, and shall be designed as follows:
(amended 2007/03/08)
- (1) Each door shall have means to safeguard against opening in flight as a result of mechanical failure, or failure of any single structural element.
  (amended 2007/03/08; no previous version)
- (2) Each door that could be a hazard if it unlatches shall be designed so that unlatching during pressurized and unpressurized flight from the fully closed, latched, and locked condition is extremely improbable. This shall be demonstrated by safety analysis.
  (amended 2007/03/08; no previous version)
- (3) Each element of each door operating system shall be designed or, where impracticable, distinctively and permanently marked, to minimize the probability of incorrect assembly and adjustment that could result in a malfunction.
  (amended 2007/03/08; no previous version)
- (4) All sources of power that could initiate unlocking or unlatching of any door shall be automatically isolated from the latching and locking systems prior to flight and it shall not be possible to restore power to the door during flight.
  (amended 2007/03/08; no previous version)
- (5) Each removable bolt, screw, nut, pin, or other removable fastener shall meet the locking requirements of 525.607.
  (amended 2007/03/08; no previous version)
- (6) Certain doors, as specified by 525.807(h), shall also meet the applicable requirements of 525.809 through 525.812 for emergency exits.
  (amended 2007/03/08; no previous version)
(b) Opening by persons. There shall be a means to safeguard each door against opening during flight due to inadvertent action by persons. In addition, design precautions shall be taken to minimize the possibility for a person to open a door intentionally during flight. If these precautions include the use of auxiliary devices, those devices and their controlling systems shall be designed so that:
(amended 2007/03/08)
- (1) No single failure will prevent more than one exit from being opened; and
  (amended 2007/03/08; no previous version)
- (2) Failures that would prevent opening of the exit after landing are improbable.
  (amended 2007/03/08; no previous version)
(c) Pressurization prevention means. There shall be a provision to prevent pressurization of the aeroplane to an unsafe level if any door subject to pressurization is not fully closed, latched, and locked.
(amended 2007/03/08)
- (1) The provision shall be designed to function after any single failure, or after any combination of failures not demonstrated to be extremely improbable.
  (amended 2007/03/08; no previous version)
- (2) Doors that meet the conditions described in (h) of this section are not required to have a dedicated pressurization prevention means if, from every possible position of the door, it will remain open to the extent that it prevents pressurization or safely close and latch as pressurization takes place. This shall also be demonstrated with any single failure and malfunction, except that:
  (amended 2007/03/08; no previous version)
  - (i) With failures or malfunctions in the latching mechanism, it need not latch after closing; and
    (amended 2007/03/08; no previous version)
  - (ii) With jamming as a result of mechanical failure or blocking debris, the door need not close and latch if it can be demonstrated that the pressurization loads on the jammed door or mechanism would not result in an unsafe condition.
    (amended 2007/03/08; no previous version)
(d) Latching and locking. The latching and locking mechanisms shall be designed as follows:
(amended 2007/03/08)
- (1) There shall be a provision to latch each door.
  (amended 2007/03/08)
- (2) The latches and their operating mechanism shall be designed so that, under all aeroplane flight and ground loading conditions, with the door latched, there is no force or torque tending to unlatch the latches. In addition, the latching system shall include a means to secure the latches in the latched position. This means shall be independent of the locking system.
  (amended 2007/03/08)
- (3) Each door subject to pressurization, and for which the initial opening movement is not inward, shall:
  (amended 2007/03/08)
  - (i) Have an individual lock for each latch;
    (amended 2007/03/08; no previous version)
  - (ii) Have the lock located as close as practicable to the latch; and
    (amended 2007/03/08; no previous version)
  - (iii) Be designed so that, during pressurized flight, no single failure in the locking system would prevent the locks from restraining the latches necessary to secure the door.
    (amended 2007/03/08; no previous version)
- (4) Each door for which the initial opening movement is inward, and unlatching of the door could result in a hazard, shall have a locking means to prevent the latches from becoming disengaged. The locking means shall ensure sufficient latching to prevent opening of the door even with a single failure of the latching mechanism.
  (amended 2007/03/08; no previous version)
- (5) It shall not be possible to position the lock in the locked position if the latch and the latching mechanism are not in the latched position.
  (amended 2007/03/08; no previous version)
- (6) It shall not be possible to unlatch the latches with the locks in the locked position. Locks shall be designed to withstand the limit loads resulting from:
  (amended 2007/03/08; no previous version)
  - (i) The maximum operator effort when the latches are operated manually;
    (amended 2007/03/08; no previous version)
  - (ii) The powered latch actuators, if installed; and
    (amended 2007/03/08; no previous version)
  - (iii) The relative motion between the latch and the structural counterpart.
    (amended 2007/03/08; no previous version)
- (7) Each door for which unlatching would not result in a hazard is not required to have a locking mechanism meeting the requirements of (d)(3) through (d)(6) of this section.
  (amended 2007/03/08; no previous version)
(e) Warning, caution, and advisory indications. Doors shall be provided with the following indications:
(amended 2007/03/08)
- (1) There shall be a positive means to indicate at each door operator's station that all required operations to close, latch, and lock the door(s) have been completed.
  (amended 2007/03/08; no previous version)
- (2) There shall be a positive means clearly visible from each operator station for any door that could be a hazard if unlatched to indicate if the door is not fully closed, latched, and locked.
  (amended 2007/03/08; no previous version)
- (3) There shall be a visual means on the flight deck to signal the pilots if any door is not fully closed, latched, and locked. The means shall be designed such that any failure or combination of failures that would result in an erroneous closed, latched, and locked indication is improbable for:
  (amended 2007/03/08; no previous version)
  - (i) Each door that is subject to pressurization and for which the initial opening movement is not inward; or
    (amended 2007/03/08; no previous version)
  - (ii) Each door that could be a hazard if unlatched.
    (amended 2007/03/08; no previous version)
- (4) There shall be an aural warning to the pilots prior to or during the initial portion of take-off roll if any door is not fully closed, latched, and locked, and its opening would prevent a safe take-off and return to landing.
  (amended 2007/03/08; no previous version)
(f) Visual inspection provision. Each door for which unlatching of the door could be a hazard shall have a provision for direct visual inspection to determine, without ambiguity, if the door is fully closed, latched, and locked. The provision shall be permanent and discernible under operational lighting conditions, or by means of a flashlight or equivalent light source.
(amended 2007/03/08)
(g) Certain maintenance doors, removable emergency exits, and access panels. Some doors not normally opened except for maintenance purposes or emergency evacuation and some access panels need not comply with certain paragraphs of this section as follows:
(amended 2007/03/08)
- (1) Access panels that are not subject to cabin pressurization and would not be a hazard if open during flight need not comply with (a) through (f) of this section, but shall have a means to prevent inadvertent opening during flight.
  (amended 2007/03/08; no previous version)
- (2) Inward-opening removable emergency exits that are not normally removed, except for maintenance purposes or emergency evacuation, and flight deck-openable windows need not comply with (c) and (f) of this section.
  (amended 2007/03/08; no previous version)
- (3) Maintenance doors that meet the conditions of (h) of this section, and for which a placard is provided limiting use to maintenance access, need not comply with (c) and (f) of this section.
  (amended 2007/03/08; no previous version)
(h) Doors that are not a hazard. For the purposes of this section, a door is considered not to be a hazard in the unlatched condition during flight, provided it can be demonstrated to meet all of the following conditions:
(amended 2007/03/08)
- (1) Doors in pressurized compartments would remain in the fully closed position if not restrained by the latches when subject to a pressure greater than 0.0352 kg/cm2 (1/2 psi). Opening by persons, either inadvertently or intentionally, need not be considered in making this determination.
  (amended 2007/03/08)
- (2) The door would remain inside the aeroplane or remain attached to the aeroplane if it opens either in pressurized or unpressurized portions of the flight. This determination shall include the consideration of inadvertent and intentional opening by persons during either pressurized or unpressurized portions of the flight.
  (amended 2007/03/08)
- (3) The disengagement of the latches during flight would not allow depressurization of the cabin to an unsafe level. This safety assessment shall include the physiological effects on the occupants.
  (amended 2007/03/08)
- (4) The open door during flight would not create aerodynamic interference that could preclude safe flight and landing.
  (amended 2007/03/08)
- (5) The aeroplane would meet the structural design requirements with the door open. This assessment shall include the aeroelastic stability requirements of 525.629, as well as the strength requirements of Subchapter C of this Chapter.
  (amended 2007/03/08)
- (6) The unlatching or opening of the door shall not preclude safe flight and landing as a result of interaction with other systems or structures.
  (amended 2007/03/08)

525.785 Seats, Berths, Safety Belts, and Harnesses

(a) A seat (or berth for a non-ambulant person) must be provided for each occupant who has reached his or her second birthday.
(b) Each seat, berth, safety belt, harness, and adjacent part of the aeroplane at each station designated as occupiable during take-off and landing must be designed so that a person making proper use of these facilities will not suffer serious injury in an emergency landing as a result of the inertia forces specified in 525.561 and 525.562.
(c) Each seat and berth must be approved.
(d) Each occupant of a seat that makes more than an 18 degree angle with the vertical plane containing the aeroplane centreline, must be protected from head injury by a safety belt and an energy absorbing rest that will support the arms, shoulders, head, and spine, or by a safety belt and shoulder harness that will prevent the head from contacting any injurious object. Each occupant of any other seat must be protected from head injury by a safety belt and, as appropriate to the type, location, and angle of facing of each seat, by one or more of the following:
- (1) A shoulder harness that will prevent the head from contacting any injurious object.
- (2) The elimination of any injurious object within striking radius of the head.
- (3) An energy absorbing rest that will support the arms, shoulders, head, and spine.
(e) Each berth must be designed so that the forward part has a padded end board, canvas diaphragm, or equivalent means, that can withstand the static load reaction of the occupant when subjected to the forward inertia force specified in 525.561. Berths must be free from corners and protuberances likely to cause serious injury to a person occupying the berth during emergency conditions.
(f) Each seat or berth, and its supporting structure, and each safety belt or harness and its anchorage must be designed for an occupant weight of 170 pounds, considering the maximum load factors, inertia forces, and reactions among the occupant, seat, safety belt, and harness for each relevant flight and ground load condition (including the emergency landing conditions prescribed in 525.561). In addition:
- (1) The structural analysis and testing of the seats, berths, and their supporting structures may be determined by assuming that the critical load in the forward, sideward, downward, upward, and rearward directions (as determined from the prescribed flight, ground, and emergency landing conditions) acts separately or using selected combinations of loads if the required strength in each specified direction is substantiated The forward load factor need not be applied to safety belts for berths.
- (2) Each pilot seat must be designed for the reactions resulting from the application of the pilot forces prescribed in 525.395.
- (3) The inertia forces specified in 525.561 must be multiplied by a factor of 1.33 (instead of the fitting factor prescribed in 525.625) in determining the strength of the attachment of each seat to the structure and each belt or harness to the seat or structure.
(g) Each seat at a flight deck station must have a restraint system consisting of a combined safety belt and shoulder harness with a single-point release that permits the flight deck occupant, when seated with the restraint system fastened, to perform all of the occupant's necessary flight deck functions. There must be a means to secure each combined restraint system, when not in use, to prevent interference with the operation of the aeroplane and with rapid egress in an emergency.
(h) Each seat located in the passenger compartment and designated for use during take-off and landing by a flight attendant required by the operating rules of this chapter must be:
- (1) Near a required floor level emergency exit, except that another location is acceptable if the emergency egress of passengers would be enhanced with that location. A flight attendant seat must be located adjacent to each Type A or B emergency exit. Other flight attendant seats must be evenly distributed among the required floor level emergency exits to the extent feasible.
- (2) To the extent possible, without compromising proximity to a required floor level emergency exit, located to provide a direct view of the cabin area for which the flight attendant is responsible.
- (3) Positioned so that the seat will not interfere with the use of a passageway or exit when the seat is not in use.
- (4) Located to minimise the probability that occupants would suffer injury by being struck by items dislodged from service areas, stowage compartments, or service equipment.
- (5) Either forward or rearward facing with an energy absorbing rest that is designed to support the arms, shoulders, head, and spine.
- (6) Equipped with a restraint system consisting of a combined safety belt and shoulder harness unit with a single point release. There must be means to secure each restraint system when not in use to prevent interference with rapid egress in an emergency.
(i) Each safety belt must be equipped with a metal to metal latching device.
(j) If the seat backs do not provide a firm hand hold, there must be a hand grip or rail along each aisle to enable persons to steady themselves while using the aisles in moderately rough air.
(k) Each projecting object that would injure persons seated or moving about the aeroplane in normal flight must be padded.
(l) Each forward observer's seat required by the operating rules must be shown to be suitable for use in conducting the necessary en route inspection.

(Change 525-1 (89-01-01))

(Change 525-3 (91-11-01))

(Change 525-8)

525.787 Stowage Compartments

(a) Each compartment for the stowage of cargo, baggage, carry-on articles, and equipment (such as life rafts), and any other stowage compartment, must be designed for its placarded maximum weight of contents and for the critical load distribution at the appropriate maximum load factors corresponding to the specified flight and ground load conditions, and to those emergency landing conditions of 525.561(b)(3) for which the breaking loose of the contents of such compartments in the specified direction could:
(effective 2019/11/01)
- (1) Cause direct injury to occupants;
  (effective 2019/11/01)
- (2) Penetrate fuel tanks or lines or cause fire or explosion hazard by damage to adjacent systems; or
  (effective 2019/11/01)
- (3) Nullify any of the escape facilities provided for use after an emergency landing.
  (effective 2019/11/01)
If the aeroplane has a passenger-seating configuration, excluding pilot seats, of 10 seats or more, each stowage compartment in the passenger cabin, except for underseat and overhead compartments for passenger convenience, must be completely enclosed.
(effective 2019/11/01)
(b) There must be a means to prevent the contents in the compartments from becoming a hazard by shifting, under the loads specified in paragraph (a) of this section. For stowage compartments in the passenger and crew cabin, if the means used is a latched door, the design must take into consideration the wear and deterioration expected in service.
(c) If cargo compartment lamps are installed, each lamp must be installed so as to prevent contact between lamp bulb and cargo.

525.789 Retention of Items of Mass in Passenger and Crew Compartments and Galleys

(a) Means must be provided to prevent each item of mass (that is part of the aeroplane type design) in a passenger or crew compartment or galley from becoming a hazard by shifting under the appropriate maximum load factors corresponding to the specified flight and ground load conditions, and to the emergency landing conditions of 525.561(b).
(b) Each interphone restraint system must be designed so that when subjected to the load factors specified in 525.561(b)(3), the interphone will remain in its stowed position.

525.791 Passenger Information Signs and Placards

(a) If smoking is to be prohibited, there must be at least one placard so stating that is legible to each person seated in the cabin. If smoking is to be allowed, and if the crew compartment is separated from the passenger compartment, there must be at least one sign notifying when smoking is prohibited. Signs which notify when smoking is prohibited must be operable by a member of the flight crew and, when illuminated, must be legible under all probable conditions of cabin illumination to each person seated in the cabin.
(b) Signs that notify when seat belts should be fastened and that are installed to comply with the applicable operating rules of this chapter must be operable by a member of the flight crew and, when illuminated, must be legible under all probable conditions of cabin illumination to each person seated in the cabin.
(c) A placard must be located on or adjacent to the door of each receptacle used for the disposal of flammable waste materials to indicate that use of the receptacle for disposal of cigarettes, etc., is prohibited.
(d) Lavatories must have "No Smoking" or "No Smoking in Lavatory" placards conspicuously located on or adjacent to each side of the entry door.
(e) Symbols that clearly express the intent of the sign or placard may be used in lieu of letters.

(Change 525-3 (91-11-01)

525.793 Floor Surfaces

The floor surface of all areas which are likely to become wet in service must have slip resistant properties.

525.794 Reserved

(Change 525-8.1 (2002-03-21); no previous version)

525.795 Security Considerations

(a) Protection of flight crew compartment. If a flight deck door is required by the applicable operating rules: (effective 2024/04/17)
- (1) The bulkhead, door and any other accessible boundary separating the flight crew compartment from occupied areas must be designed to resist forcible intrusion by unauthorized persons and be capable of withstanding impacts of 300 Joules (221.3 foot-pounds);
  (amended 2010/06/16)
- (2) The bulkhead, door and any other accessible boundary separating the flight crew compartment from occupied areas must be designed to resist a constant 250 pound (1113 Newtons) tensile load on accessible handholds, including the doorknob or handle;
  (amended 2010/06/16)
- (3) The bulkhead, door and any other boundary separating the flight crew compartment from any occupied areas must be designed to resist penetration by small arms fire and fragmentation devices to a level equivalent to level IIIa of the U.S. National Institute of Justice Standard, NIJ Standard - 0101.04.
  (amended 2010/06/16)
- (4) If required by the applicable operating rules, an installed physical secondary barrier (IPSB) must be installed to resist intrusion into the flight deck whenever the flight deck door is opened. When deployed, the IPSB must: (effective 2024/04/17)
  - (i) Resist a 250 pound (1113 Newtons) static load in the direction of the passenger cabin applied at the most critical locations on the IPSB; (effective 2024/04/17)
  - (ii) Resist a 600 pound (2669 Newtons) static load in the direction of the flight deck applied at the most critical locations on the IPSB; (effective 2024/04/17)
  - (iii) Delay a person attempting to access the flight deck by at least the time required for a crew member to open and reclose the flight deck door, but no less than 5 seconds; (effective 2024/04/17)
  - (iv) Prevent a person from reaching through and touching the flight deck door; (effective 2024/04/17)
  - (v) Allow for necessary crew member activities; and (effective 2024/04/17)
  - (vi) Provide line-of-sight visibility between the flight deck door and the cabin. (effective 2024/04/17)
(b) Aeroplanes with a maximum certificated passenger seating capacity of more than 60 persons or a maximum certificated take-off gross weight of over 100,000 pounds (45,359 Kilograms) must be designed to limit the effects of an explosive or incendiary device as follows:
(amended 2010/06/16)
- (1) Flight deck smoke protection. Means must be provided to limit entry of smoke, fumes and noxious gases into the flight deck;
- (2) Passenger cabin smoke protection. Means must be provided to prevent passenger incapacitation in the cabin resulting from smoke, fumes and noxious gases as represented by the initial combined volumetric concentrations of 0.59% carbon monoxide and 1.23% carbon dioxide;
- (3) Cargo compartment fire suppression. An extinguishing agent must be capable of suppressing a fire. All cargo-compartment fire suppression systems must be designed to withstand the following effects, including support structure displacements or adjacent materials displacing against the distribution system:
  - (i) Impact or damage from a 0.5-inch diameter aluminum sphere traveling at 430 feet per second (131.1 metres per second);
  - (ii) A 15-pound per square-inch (103.4 kPa) pressure load if the projected surface area of the component is greater than 4 square feet. Any single dimension greater than 4 feet (1.22 metres) may be assumed to be 4 feet (1.22 metres) in length;
  - (iii) A 6-inch (0.152 metres) displacement, except where limited by the fuselage contour, from a single point force applied anywhere along the distribution system where relative movement between the system and its attachment can occur;
  - (iv) Subparagraphs (b)(3)(i) through (iii) of this section do not apply to components that are redundant and separated in accordance with paragraph (c)(2) of this section or are installed remotely from the cargo compartment.
(c) An aeroplane with a maximum certificated passenger seating capacity of more than 60 persons or a maximum certificated take-off gross weight of over 100,000 pounds (45,359 Kilograms) must comply with the following:
(amended 2010/06/16; no previous version)
- (1) Least risk bomb location. An aeroplane must be designed with a designated location where a bomb or other explosive device could be placed to best protect flight-critical structures and systems from damage in the case of detonation.
- (2) Survivability of systems:
  - (i) Except where impracticable, redundant aeroplane systems necessary for continued safe flight and landing must be physically separated, at a minimum, by an amount equal to a sphere of diameter
    D = 2 v (H₀ / P )
    (where H₀ is defined under 525.365(e)(2) and D need not exceed 5.05 feet (1.54 metres)). The sphere is applied everywhere within the fuselage limited by the forward bulkhead and the aft bulkhead of the passenger cabin and cargo compartment beyond which, only one-half the sphere is applied.
  - (ii) Where compliance with subparagraph (c)(2)(i) of this section is impracticable, other design precautions must be taken to maximize the survivability of those systems.
- (3) Interior design to facilitate searches. Design features must be incorporated that will deter concealment or promote discovery of weapons, explosives or other objects from a simple inspection in the following areas of the aeroplane cabin:
  - (i) Areas above the overhead bins must be designed to prevent objects from being hidden from view in a simple search from the aisle. Designs that prevent concealment of objects with volumes 20 cubic inches and greater satisfy this requirement.
  - (ii) Toilets must be designed to prevent the passage of solid objects greater than 2.0 inches in diameter.
  - (iii) Life preservers or their storage locations must be designed so that tampering is evident.
(d) Each chemical oxygen generator or its installation must be designed to be secure from deliberate manipulation by one of the following means:
(effective 2015/03/20)
- (1) by providing effective resistance to tampering,
- (2) by providing an effective combination of resistance to tampering and active tamper-evident features,
- (3) by installation in a location or manner whereby any attempt to access the generator would be immediately obvious, or
- (4) by a combination of approaches specified in (d)(1), (d)(2) and(d)(3) of this section that the Minister finds provides a secure installation.
(e) Exceptions. Aeroplanes used solely to transport cargo only need to meet the requirements of (b)(1), (b)(3) and (c)(2) of this section.
(effective 2015/03/20)
(f) Material Incorporated by Reference. You must use National Institute of Justice, NIJ Standard 0101.04, Ballistic Resistance of Personal Body Armor, June 2001, Revision A, to establish ballistic resistance as required by paragraph (a)(3) of this section.
(effective 2020/01/14)

Information notes:
(amended 2010/06/16; no previous version)
- (i) You may review copies of NIJ Standard 0101.04 at the:
  (effective 2020/01/14)
  - (A) National Institute of Justice (NIJ), http://www.ojp.usdoj.gov/nij, telephone (202) 307-2942; or
  - (B) National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call (202) 741-6030, or go to http://www.archives.gov/federal-register/cfr/ibr-locations.html; or
- (ii) You may obtain copies of NIJ Standard 0101.04 from the National Criminal Justice Reference Service, P.O. Box 6000, Rockville, MD 20849–6000, telephone (800) 851-3420.

Emergency Provisions

525.801 Ditching

(a) If certification with ditching provisions is requested, the aeroplane must meet the requirements of this section and 525.807(e), 525.1411, and 525.1415(a).
(b) Each practicable design measure, compatible with the general characteristics of the aeroplane, must be taken to minimise the probability that in an emergency landing on water, the behaviour of the aeroplane would cause immediate injury to the occupants or would make it impossible for them to escape.
(c) The probable behaviour of the aeroplane in a water landing must be investigated by model tests or by comparison with aeroplanes of similar configuration for which the ditching characteristics are known. Scoops, flaps, projections, and any other factor likely to affect the hydro-dynamic characteristics of the aeroplane, must be considered.
(d) It must be shown that, under reasonably probable water conditions, the flotation time and trim of the aeroplane will allow the occupants to leave the aeroplane and enter the life rafts required by 525.1415. If compliance with this provision is shown by buoyancy and trim computations, appropriate allowances must be made for probable structural damage and leakage. If the aeroplane has fuel tanks (with fuel jettisoning provisions) that can reasonably be expected to withstand a ditching without leakage, the jettisonable volume of fuel may be considered as buoyancy volume.
(e) Unless the effects of the collapse of external doors and windows are accounted for in the investigation of the probable behaviour of the aeroplane in a water landing (as prescribed in paragraphs (c) and (d) of this section), the external doors and windows must be designed to withstand the probable maximum local pressures.

(Change 525-3 (91-11-01))

525.803 Emergency Evacuation

(a) Each crew and passenger area must have emergency means to allow rapid evacuation in crash landings, with the landing gear extended as well as with the landing gear retracted, considering the possibility of the aeroplane being on fire.
(b) (Reserved)
(c) For aeroplanes having a seating capacity of more than 44 passengers, it must be shown that the maximum seating capacity, including the number of crew members required by the operating rules for which certification is requested, can be evacuated from the aeroplane to the ground under simulated emergency conditions within 90 seconds. Compliance with this requirement must be shown by actual demonstration using the test criteria outlined in Appendix J of this chapter unless the Minister finds that a combination of analysis and testing will provide data equivalent to that which would be obtained by actual demonstration.
(d) (Reserved)
(e) (Reserved)

(Change 525-3 (91-11-01))

525.807 Emergency Exits

(a) Type. For the purpose of this chapter, the types of exits are defined as follows:
- (1) Type I. This type is a floor-level exit with a rectangular opening of not less than 24 inches wide by 48 inches high, with corner radii not greater than eight inches.
- (2) Type II. This type is a rectangular opening of not less than 20 inches wide by 44 inches high, with corner radii not greater than seven inches. Type II exits shall be floor-level exits unless located over the wing, in which case they shall not have a step-up inside the aeroplane of more than 10 inches nor a step-down outside the aeroplane of more than 17 inches.
  (amended 2007/03/08)
- (3) Type III. This type is a rectangular opening of not less than 20 inches wide by 36 inches high with corner radii not greater than seven inches, and with a step-up inside the aeroplane of not more than 20 inches. If the exit is located over the wing, the step-down outside the aeroplane may not exceed 27 inches.
- (4) Type IV. This type is a rectangular opening of not less than 19 inches wide by 26 inches high, with corner radii not greater than 6.3 inches, located over the wing, with a step-up inside the aeroplane of not more than 29 inches and a step-down outside the aeroplane of not more than 36 inches.
- (5) Ventral. This type is an exit from the passenger compartment through the pressure shell and the bottom fuselage skin. The dimensions and physical configuration of this type of exit shall allow at least the same rate of egress as a Type I with the aeroplane in the normal ground attitude, with landing gear extended.
  (amended 2007/03/08)
- (6) Tailcone. This type is an aft exit from the passenger compartment through the pressure shell and through an openable cone of the fuselage aft of the pressure shell. The means of opening the tail cone shall be simple and obvious, and shall employ a single operation.
  (amended 2007/03/08)
- (7) Type A. This type is a floor-level exit with a rectangular opening of not less than 42 inches wide by 72 inches high, with corner radii not greater than seven inches.
- (8) Type B. This type is a floor-level exit with a rectangular opening of not less than 32 inches wide by 72 inches high, with corner radii not greater than six inches.
- (9) Type C. This type is a floor-level exit with a rectangular opening of not less than 30 inches wide by 48 inches high, with corner radii not greater than 10 inches.
(b) Step down distance. Step down distance, as used in this section, means the actual distance between the bottom of the required opening and a usable foot hold, extending out from the fuselage, that is large enough to be effective without searching by sight or feel.
(c) Over-sized exits. Openings larger that those specified in this section, whether or not of rectangular shape, may be used if the specified rectangular opening can be inscribed within the opening and the base of the inscribed rectangular opening meets the specified step-up and step-down heights.
(d) Asymmetry. Exits of an exit pair need not be diametrically opposite each other nor of the same size; however, the number of passenger seats permitted under paragraph (g) of this section is based on the smaller of the two exits.
(e) Uniformity. Exits shall be distributed as uniformly as practical, taking into account passenger seat distribution.
(amended 2007/03/08)
(f) Location.
- (1) Each required passenger emergency exit shall be accessible to the passengers and located where it will afford the most effective means of passenger evacuation.
  (amended 2007/03/08)
- (2) If only one floor-level exit per side is prescribed, and the aeroplane does not have a tail-cone or ventral emergency exit, the floor-level exits shall be in the rearward part of the passenger compartment unless another location affords a more effective means of passenger evacuation.
  (amended 2007/03/08)
- (3) If more than one floor-level exit per side is prescribed, and the aeroplane does not have a combination cargo and passenger configuration, at least one floor-level exit shall be located in each side near each end of the cabin.
  (amended 2007/03/08)
- (4) For an aeroplane that is required to have more than one passenger emergency exit for each side of the fuselage, no passenger emergency exit shall be more than 60 feet from any adjacent passenger emergency exit on the same side of the same deck of the fuselage, as measured parallel to the aeroplane's longitudinal axis between the nearest exit edges.
(g)Type and number required. The maximum number of passenger seats permitted depends on the type and number of exits installed in each side of the fuselage. Except as further restricted in (g)(1) through (g)(9) of this section, the maximum number of passenger seats permitted for each exit of a specific type installed in each side of the fuselage is as follows:
(amended 2007/03/08)

Type A	110
Type B	75
Type C	55
Type I	45
Type II	40
Type III	35
Type IV	9

- (1) For a passenger seating configuration of 1 to 9 seats, there shall be at least one Type IV or larger overwing exit in each side of the fuselage or, if overwing exits are not provided, at least one exit in each side that meets the minimum dimensions of a Type III exit.
  (amended 2007/03/08)
- (2) For a passenger seating configuration of more than 9 seats, each exit shall be a Type III or larger exit.
  (amended 2007/03/08)
- (3) For a passenger seating configuration of 10 to 19 seats, there shall be at least one Type III or larger exit in each side of the fuselage.
  (amended 2007/03/08)
- (4) For a passenger seating configuration of 20 to 40 seats, there shall be at least two exits, one of which must be a Type II or larger exit, in each side of the fuselage.
  (amended 2007/03/08)
- (5) For a passenger seating configuration of 41 to 110 seats, there shall be at least two exits, one of which must be a Type I or larger exit, in each side of the fuselage.
  (amended 2007/03/08)
- (6) For a passenger seating configuration of more than 110 seats, the emergency exits in each side of the fuselage shall include at least two Type I or larger exits.
  (amended 2007/03/08)
- (7) The combined maximum number of passenger seats permitted for all Type III exits is 70, and the combined maximum number of passenger seats permitted for two Type III exits in each side of the fuselage that are separated by fewer than three passenger seat rows is 65.
- (8) If a Type A, Type B, or Type C exit is installed, there shall be at least two Type C or larger exits in each side of the fuselage.
  (amended 2007/03/08)
- (9) If a passenger ventral or tail cone exit is installed and that exit provides at least the same rate of egress as a Type III exit with the aeroplane in the most adverse exit opening condition that would result from the collapse of one or more legs of the landing gear, an increase in the passenger seating configuration is permitted as follows:
  - (i) For a ventral exit, 12 additional passenger seats.
  - (ii) For a tail cone exit incorporating a floor level opening of not less than 20 inches wide by 60 inches high, with corner radii not greater than seven inches, in the pressure shell and incorporating an approved assist means in accordance with 525.810(a), 25 additional passenger seats.
    (amended 2007/03/08)
  - (iii) For a tail cone exit incorporating an opening in the pressure shell which is at least equivalent to a Type III emergency exit with respect to dimensions, step-up and step-down distance, and with the top of the opening not less than 56 inches from the passenger compartment floor, 15 additional passenger seats.
(h) Other exits. The following exits also shall meet the applicable emergency exit requirements of 525.809 through 525.812, and shall be readily accessible:
(amended 2007/03/08)
- (1) Each emergency exit in the passenger compartment in excess of the minimum number of required emergency exits.
  (amended 2007/03/08)
- (2) Any other floor-level door or exit that is accessible from the passenger compartment and is as large or larger than a Type II exit, but less than 46 inches wide.
  (amended 2007/03/08; no previous version)
- (3) Any other ventral or tail cone passenger exit.
  (amended 2007/03/08; no previous version)
(i) Ditching emergency exits for passengers. Whether or not ditching certification is requested, ditching emergency exits shall be provided in accordance with the following requirements, unless the emergency exits required by (g) of this section already meet them:
(amended 2007/03/08)
- (1) For aeroplanes that have a passenger seating configuration of nine or fewer seats, excluding pilot seats, one exit above the waterline in each side of the aeroplane, meeting at least the dimensions of a Type IV exit.
- (2) For aeroplanes that have a passenger seating configuration of 10 or more seats, excluding pilot seats, one exit above the waterline in a side of the aeroplane, meeting at least the dimensions of a Type III exit for each unit (or part of a unit) of 35 passenger seats, but no less than two such exits in the passenger cabin, with one on each side of the aeroplane. The passenger seat/ exit ratio may be increased through the use of larger exits, or other means, provided it is demonstrated that the evacuation capability during ditching has been improved accordingly.
  (amended 2007/03/08)
- (3) If it is impractical to locate side exits above the waterline, the side exits shall be replaced by an equal number of readily accessible overhead hatches of not less than the dimensions of a Type III exit, except that for aeroplanes with a passenger configuration of 35 or fewer seats, excluding pilot seats, the two required Type III side exits need be replaced by only one overhead hatch.
  (amended 2007/03/08)
(j) Flight crew emergency exits. For aeroplanes in which the proximity of passenger emergency exits to the flight crew area does not offer a convenient and readily accessible means of evacuation of the flight crew, and for all aeroplanes having a passenger seating capacity greater than 20, flight crew exits shall be located in the flight crew area. Such exits shall be of sufficient size and so located as to permit rapid evacuation by the crew. One exit shall be provided on each side of the aeroplane; or, alternatively, a top hatch shall be provided. Each exit shall encompass an unobstructed rectangular opening of at least 19 by 20 inches unless satisfactory exit utility can be demonstrated by a typical crew member.
(amended 2007/03/08)

(Change 525-3 (91-11-01))

(Change 525-8)

525.809 Emergency Exit Arrangement

(a) Each emergency exit, including a flight crew emergency exit, shall be a movable door or hatch in the external walls of the fuselage, allowing unobstructed opening to the outside. In addition, each emergency exit shall have a means to permit viewing of the conditions outside the exit when the exit is closed. The viewing means may be on or adjacent to the exit provided no obstructions exist between the exit and the viewing means. Means shall also be provided to permit viewing of the likely areas of evacuee ground contact. The likely areas of evacuee ground contact shall be viewable during all lighting conditions with the landing gear extended as well as in all conditions of landing gear collapse.
(amended 2007/03/08)
(b) Each emergency exit shall be openable from the inside and the outside except that sliding window emergency exits in the flight crew area need not be openable from the outside if other approved exits are convenient and readily accessible to the flight crew area. Each emergency exit shall be capable of being opened, when there is no fuselage deformation:
(amended 2007/03/08)
- (1) With the aeroplane in the normal ground attitude and in each of the attitudes corresponding to collapse of one or more legs of the landing gear; and
- (2) Within 10 seconds measured from the time when the opening means is actuated to the time when the exit is fully opened.
- (3) Even though persons may be crowded against the door on the inside of the aeroplane.
  (amended 2007/03/08)
(c) The means of opening emergency exits shall be simple and obvious; may not require exceptional effort; and shall be arranged and marked so that it can be readily located and operated, even in the darkness. Internal exit-opening means involving sequence operations (such as operation of two handles or latches or the release of safety catches) may be used for flight crew emergency exits if it can be reasonably established that these means are simple and obvious to crew members trained in their use.
(amended 2007/03/08)
(d) If a single power-boost or single power-operated system is the primary system for operating more than one exit in an emergency, each exit shall be capable of meeting the requirements of (b) of this section in the event of failure of the primary system. Manual operation of the exit (after failure of the primary system) is acceptable.
(amended 2007/03/08)
(e) Each emergency exit shall be demonstrated by tests, or by a combination of analysis and tests, to meet the requirements of (b) and (c) of this section.
(amended 2007/03/08)
(f) Each door shall be located where persons using them will not be endangered by the propellers when appropriate operating procedures are used.
(amended 2007/03/08)
(g) There shall be provisions to minimize the probability of jamming of the emergency exits resulting from fuselage deformation in a minor crash landing.
(amended 2007/03/08)
(h) When required by the operating rules for any large passenger-carrying turbojet-powered aeroplane, each ventral exit and tailcone exit shall be:
(amended 2007/03/08)
- (1) Designed and constructed so that it cannot be opened during flight; and
- (2) Marked with a placard readable from a distance of 30 inches and installed at a conspicuous location near the means of opening the exit, stating that the exit has been designed and constructed so that it cannot be opened during flight.
(i) Each emergency exit shall have a means to retain the exit in the open position, once the exit is opened in an emergency. The means shall not require separate action to engage when the exit is opened, and shall require positive action to disengage.
(amended 2007/03/08; no previous version)

(Change 525-3 (91-11-01))

525.810 Emergency Egress Assist Means and Escape Routes

(a) Each non over-wing Type A, Type B or Type C exit, and any other non over-wing landplane emergency exit more than 6 feet from the ground with the aeroplane on the ground and the landing gear extended, shall have an approved means to assist the occupants in descending to the ground.
(amended 2007/03/08)
- (1) The assisting means for each passenger emergency exit shall be a self-supporting slide or equivalent; and, in the case of Type A or Type B exits, it shall be capable of carrying simultaneously two parallel lines of evacuees. In addition, the assisting means shall be designed to meet the following requirements:
  (amended 2007/03/08)
  - (i) It shall be automatically deployed and deployment shall begin during the interval between the time the exit opening means is actuated from inside the aeroplane and the time the exit is fully opened. However, each passenger emergency exit which is also a passenger entrance door or a service door shall be provided with means to prevent deployment of the assisting means when it is opened from either the inside or the outside under non-emergency conditions for normal use.
    (amended 2007/03/08)
  - (ii) Except for assisting means installed at Type C exits, it shall be automatically erected within 6 seconds after deployment is begun. Assisting means installed at Type C exits shall be automatically erected within 10 seconds from the time the opening means of the exit is actuated.
    (amended 2007/03/08)
  - (iii) It shall be of such length after full deployment that the lower end is self-supporting on the ground and provides safe evacuation of occupants to the ground after collapse of one or more legs of the landing gear.
    (amended 2007/03/08)
  - (iv) It shall have the capability, in 25 knot winds directed from the most critical angle, to deploy and, with the assistance of only one person to remain usable after full deployment to evacuate occupants safely to the ground.
    (amended 2007/03/08)
  - (v) For each system installation (mock-up or aeroplane installed), five consecutive deployment and inflation tests shall be conducted (per exit) without failure, and at least three tests of each such five-test series shall be conducted using a single representative sample of the device. The sample devices must be deployed and inflated by the system's primary means after being subjected to the inertia forces specified in 525.561(b). If any part of the system fails or does not function properly during the required test, the cause of the failure or malfunction shall be corrected by positive means and after that, the full series of five consecutive deployment and inflation tests shall be conducted without failure.
    (amended 2007/03/08)
- (2) The assisting means for flight crew emergency exits may be a rope or any other means demonstrated to be suitable for the purpose. If the assisting means is a rope, or an approved device equivalent to a rope, it shall be:
  (amended 2007/03/08)
  - (i) Attached to the fuselage structure at or above the top of the emergency exit opening, or, for a device at a pilot's emergency exit window, at another approved location if the stowed device, or its attachment, would reduce the pilot's view in flight:
  - (ii) Able (with its attachment) to withstand a 400-pound static load.
(b) Assist means from the cabin to the wing are required for each Type A or Type B exit located above the wing and having a step-down unless the exit without an assist-means can be shown to have a rate of passenger egress at least equal to that of the same type of non over-wing exit. If an assist means is required, it shall be automatically deployed and automatically erected concurrent with the opening of the exit. In the case of assist means installed at Type C exits, it shall be self-supporting within 10 seconds from the time the opening means of the exits is actuated. For all other exit types, it shall be self-supporting 6 seconds after deployment is begun.
(amended 2007/03/08)
(c) An escape route shall be established from each overwing emergency exit, and (except for flap surfaces suitable as slides) covered with a slip resistant surface. Except where a means for channelling the flow of evacuees is provided:
- (1) The escape route from each Type A or Type B passenger emergency exit, or any common escape route from two Type III passenger emergency exits, shall be at least 42 inches wide; that from any other passenger emergency exit shall be at least 24 inches wide; and
  (amended 2007/03/08)
- (2) The escape route surface shall have a reflectance of at least 80 percent, and shall be defined by markings with a surface-to-marking contrast ratio of at least 5:1.
  (amended 2007/03/08)
(d) Means shall be provided to assist evacuees to reach the ground for all Type C exits located over the wing and, if the place on the aeroplane structure at which the escape route required in (c) of this section terminates is more than 6 feet from the ground with the aeroplane on the ground and the landing gear extended, for all other exit types.
(amended 2007/03/08)
- (1) If the escape route is over the flap, the height of the terminal edge shall be measured with the flap in the take-off or landing position, whichever is higher from the ground.
  (amended 2007/03/08)
- (2) The assisting means shall be usable and self-supporting with one or more landing gear legs collapsed and under a 25-knot wind directed from the most critical angle.
  (amended 2007/03/08)
- (3) The assisting means provided for each escape route leading from a Type A or B emergency exit shall be capable of carrying simultaneously two parallel lines of evacuees; and, the assisting means leading from any other exit type shall be capable of carrying as many parallel lines of evacuees as there are required escape routes.
  (amended 2007/03/08)
- (4) The assisting means provided for each escape route leading from a Type C exit shall be automatically erected within 10 seconds from the time the opening means of the exit is actuated, and that provided for the escape route leading from any other exit type must be automatically erected within 10 seconds after actuation of the erection system.
  (amended 2007/03/08)
(e) If an integral stair is installed in a passenger entry door that is qualified as a passenger emergency exit, the stair shall be designed so that, under the following conditions, the effectiveness of passenger emergency egress will not be impaired:
(amended 2007/03/08; no previous version)
- (1) The door, integral stair, and operating mechanism have been subjected to the inertia forces specified in 525.561(b)(3), acting separately relative to the surrounding structure.
  (amended 2007/03/08; no previous version)
- (2) The aeroplane is in the normal ground attitude and in each of the attitudes corresponding to collapse of one or more legs of the landing gear.
  (amended 2007/03/08; no previous version)

(Change 525-3 (91-11-01))

(Change 525-8)

525.811 Emergency Exit Marking

(a) Each passenger emergency exit, its means of access, and its means of opening must be conspicuously marked.
(b) The identity and location of each passenger emergency exit must be recognisable from a distance equal to the width of the cabin.
(c) Means must be provided to assist the occupants in locating the exits in conditions of dense smoke.
(d) The location of each passenger emergency exit must be indicated by a sign visible to occupants approaching along the main passenger aisle (or aisles). There must be:
- (1) A passenger emergency exit locator sign above the aisle (or aisles) near each passenger emergency exit, or at another overhead location if it is more practical because of low headroom, except that one sign may serve more than one exit if each exit can be seen readily from the sign;
- (2) A passenger emergency exit marking sign next to each passenger emergency exit, except that one sign may serve two such exits if they both can be seen readily from the sign; and
- (3) A sign on each bulkhead or divider that prevents fore and aft vision along the passenger cabin to indicate emergency exits beyond and obscured by the bulkhead or divider, except that if this is not possible the sign may be placed at another appropriate location.
(e) The location of the operating handle and instructions for opening exits from the inside of the aeroplane must be shown in the following manner:
- (1) Each passenger emergency exit must have, on or near the exit, a marking that is readable from a distance of 30 inches.
- (2) Each Type A, Type B, Type C or Type I passenger emergency exit operating handle must:
  - (i) Be self-illuminated with an initial brightness of at least 160 microlamberts; or
  - (ii) Be conspicuously located and well illuminated by the emergency lighting even in conditions of occupant crowding at the exit.
- (3) (Reserved)
- (4) Each Type A, Type B, Type C, Type I, or Type II passenger emergency exit with a locking mechanism released by rotary motion of the handle must be marked:
  - (i) With a red arrow, with a shaft at least three-fourths of an inch wide and a head twice the width of the shaft, extending along at least 70 degrees of arc at a radius approximately equal to three-fourths of the handle length.
  - (ii) So that the centreline of the exit handle is within + 1 inch of the projected point of the arrow when the handle has reached full travel and has released the locking mechanism, and
  - (iii) With the word "open" in red letters 1 inch high, placed horizontally near the head of the arrow.
(f) Each emergency exit that is required to be openable from the outside, and its means of opening, must be marked on the outside of the aeroplane. In addition, the following apply:
- (1) The outside marking for each passenger emergency exit in the side of the fuselage must include a 2-inch coloured band outlining the exit.
- (2) Each outside marking including the band, must have colour contrast to be readily distinguishable from the surrounding fuselage surface. The contrast must be such that if the reflectance of the darker colour is 15 percent or less, the reflectance of the lighter colour must be at least 45 percent. "Reflectance" is the ratio of the luminous flux reflected by a body to the luminous flux it receives. When the reflectance of the darker colour is greater than 15 percent, at least a 30 percent difference between its reflectance and the reflectance of the lighter colour must be provided.
- (3) In the case of exits other than those in the side of the fuselage, such as ventral or tail cone exits, the external means of opening, including instructions if applicable, must be conspicuously marked in red, or bright chrome yellow if the background colour is such that red is inconspicuous. When the opening means is located on only one side of the fuselage, a conspicuous marking to that effect must be provided on the other side.
(g) Each sign required by paragraph (d) of this section may use the word "exit" in its legend in the place of the term "emergency exit".

(Change 525-3 (91-11-01))

(Change 525-6 (93-12-30))

(Change 525-8)

525.812 Emergency Lighting

(a) An emergency lighting system, independent of the main lighting system, must be installed. However, the sources of general cabin illumination may be common to both the emergency and the main lighting systems if the power supply to the emergency lighting system is independent of the power supply to the main lighting system. The emergency lighting system must include:
- (1) Illuminated emergency exit marking and locating signs, sources of general cabin illumination, interior lighting in emergency exit areas, and floor proximity escape path marking.
- (2) Exterior emergency lighting.
(b) Emergency exit signs:
- (1) For aeroplanes that have a passenger seating configuration, excluding pilot seats, of 10 seats or more must meet the following requirements:
  - (i) Each passenger emergency exit locator sign required by 525.811(d)(1) and each passenger emergency exit marking sign required by 525.811(d)(2) must have red letters at least 1½ inches high on an illuminated white background, and must have an area of at least 21 square inches excluding the letters. The lighted background-to-letter contrast must be at least 10:1. The letter height to stroke-width ratio may not be more than 7:1 nor less than 6:1. These signs must be internally electrically illuminated with a background brightness of at least 25 foot-lamberts and a high-to-low background contrast no greater than 3:1.
  - (ii) Each passenger emergency exit sign required by 525.811(d)(3) must have red letters at least 1½ inches high on a white background having an area of at least 21 square inches excluding the letters. These signs must be internally electrically illuminated or self-illuminated by other than electrical means and must have an initial brightness of at least 400 microlamberts. The colours may be reversed in the case of a sign that is self-illuminated by other than electrical means.
- (2) For aeroplanes that have a passenger seating configuration, excluding pilot seats, of nine seats or less, that are required by 525.811(d)(1), (2) and (3) must have red letters at least 1 inch high on a white background at least 2 inches high. These signs may be internally electrically illuminated, or self-illuminated by other than electrical means, with an initial brightness of at least 160 microlamberts. The colours may be reversed in the case of a sign that is self-illuminated by other than electrical means.
(c) General illumination in the passenger cabin must be provided so that when measured along the centreline of main passenger aisle(s), and cross aisle(s) between main aisles, at seat armrest height and at 40-inch intervals, the average illumination is not less than 0.05 foot-candle and the illumination at each 40-inch interval is not less than 0.01 foot-candle. A main passenger aisle(s) is considered to extend along the fuselage from the most forward passenger emergency exit or cabin occupant seat, whichever is farther forward, to the most rearward passenger emergency exit or cabin occupant seat, whichever is farther aft.
(d) The floor of the passageway leading to each floor-level passenger emergency exit, between the main aisles and the exit openings, must be provided with illumination that is not less than 0.02 foot-candle measured along a line that is within 6 inches of and parallel to the floor and is centred on the passenger evacuation path.
(e) Floor proximity emergency escape path markings must provide emergency evacuation guidance for passengers when all sources of illumination more than 4 feet above the cabin aisle floor are totally obscured. In the dark of the night, the floor proximity emergency escape path markings must enable each passenger to:
- (1) After leaving the passenger seat visually identify the emergency escape path along the cabin aisle floor to the first exits or pair of exits forward and aft of the seat; and
- (2) Readily identify each exit from the emergency escape path by reference only to markings and visual features not more than 4 feet above the cabin floor.
(f) Except for subsystems provided in accordance with paragraph (h) of this section that serve no more than one assist means, are independent of the aeroplane's main emergency lighting system, and are automatically activated when the assist means is erected, the emergency lighting system must be designed as follows:
- (1) The lights must be operable manually from the flight crew station and from a point in the passenger compartment that is readily accessible to a normal flight attendant seat.
- (2) There must be a flight crew warning light which illuminates when power is on in the aeroplane and the emergency lighting control device is not armed.
- (3) The cockpit control device must have an "on," "off," and "armed" position so that when armed in the cockpit or turned on at either the cockpit or flight attendant station the lights will either light or remain lighted upon interruption (except an interruption caused by a transverse vertical separation of the fuselage during crash landing) of the aeroplane's normal electric power. There must be a means to safeguard against inadvertent operation of the control device from the "armed" or "on" positions.
(g) Exterior emergency lighting must be provided as follows:
- (1) At each overwing emergency exit the illumination shall be:
  (amended 2007/03/08)
  - (i) Not less than 0.03 foot-candle (measured normal to the direction of the incident light) on a 2-square-foot area where an evacuee is likely to make his first step outside the cabin;
  - (ii) Not less than 0.05 foot-candle (measured normal to the direction of incident light) for a minimum width of 42 inches for a Type A over wing emergency exit and two feet for all other over wing emergency exits along the 30 percent of the slip-resistant portion of the escape route required in 525.810(c) that is farthest from the exit; and
    (amended 2007/03/08)
  - (iii) Not less than 0.03 foot-candle on the ground surface with the landing gear extended (measured normal to the direction of the incident light) where an evacuee using the established escape route would normally make first contact with the ground.
- (2) At each non-overwing emergency exit not required by 525.810(a) to have descent assist means, the illumination shall be not less than 0.03 foot-candle (measured normal to the direction of the incident light) on the ground surface with the landing gear extended where an evacuee is likely to make his first contact with the ground outside the cabin.
  (amended 2007/03/08)
(h) The means required in 525.810(a)(1) and (d) to assist the occupants in descending to the ground must be illuminated so that the erected assist means is visible from the aeroplane. In addition:
(amended 2012/03/27)
- (1) If the assist means is illuminated by exterior emergency lighting, it must provide illumination of not less than 0.03 foot-candle (measured normal to the direction of the incident light) at the ground end of the erected assist means where an evacuee using the established escape route would normally make first contact with the ground, with the aeroplane in each of the attitudes corresponding to the collapse of one or more legs of the landing gear.
- (2) If the emergency lighting subsystem illuminating the assist means serves no other assist means, is independent of the aeroplane's main emergency lighting system, and is automatically activated when the assist means is erected, the lighting provisions:
  - (i) May not be adversely affected by stowage; and
  - (ii) Must provide illumination of not less than 0.03 foot-candle (measured normal to the direction of incident light) at the ground end of the erected assist means where an evacuee would normally make first contact with the ground, with the aeroplane in each of the attitudes corresponding to the collapse of one or more legs of the landing gear.
(i) The energy supply to each emergency lighting unit must provide the required level of illumination for at least 10 minutes at the critical ambient conditions after emergency landing.
(j) If storage batteries are used as the energy supply for the emergency lighting system, they may be recharged from the aeroplane's main electric power system, provided, that, the charging circuit is designed to preclude inadvertent battery discharge into charging circuit faults.
(k) Components of the emergency lighting system, including batteries, wiring relays, lamps, and switches must be capable of normal operation after having been subjected to the inertia forces listed in 525.561(b).
(l) The emergency lighting system must be designed so that after any single transverse vertical separation of the fuselage during crash landing:
- (1) Not more than 25 percent of all electrically illuminated emergency lights required by this section are rendered inoperative, in addition to the lights that are directly damaged by the separation;
- (2) Each electrically illuminated exit sign required under 525.811(d)(2) remains operative exclusive of those that are directly damaged by the separation; and
- (3) At least one required exterior emergency light for each side of the aeroplane remains operative exclusive of those that are directly damaged by the separation.

(Change 525-8)

525.813 Emergency Exit Access

Each required emergency exit must be accessible to the passengers and located where it will afford an effective means of evacuation. Emergency exit distribution must be as uniform as practical, taking passenger distribution into account; however, the size and location of exits on both sides of the cabin need not be symmetrical. If only one floor level exit per side is prescribed, and the aeroplane does not have a tail cone or ventral emergency exit, the floor level exit must be in the rearward part of the passenger compartment, unless another location affords a more effective means of passenger evacuation. Where more than one floor level exit per side is prescribed, at least one floor level exit per side must be located near each end of the cabin, except that this provision does not apply to combination cargo/passenger configurations. In addition:

(a) There must be a passageway leading from the nearest main aisle to each Type A, Type B, Type C, Type I, or Type II emergency exit and between individual passenger areas. Each passageway leading to a Type A or Type B exit must be unobstructed and at least 36 inches wide. Passageways between individual passenger areas and those leading to Type I, Type II, or Type C emergency exits must be unobstructed and at least 20 inches wide. Unless there are two or more main aisles, each Type A or B exit must be located so that there is passenger flow along the main aisle to that exit from both the forward and aft directions. If two or more main aisles are provided, there must be unobstructed cross-aisles at least 20 inches wide between main aisles. There must be:
- (1) A cross-aisle which leads directly to each passageway between the nearest main aisle and a Type A or B exit; and
- (2) A cross-aisle which leads to the immediate vicinity of each passageway between the nearest main aisle and a Type I, Type II, or Type III exit; except that when two Type III exits are located within three passenger rows of each other, a single cross-aisle may be used if it leads to the vicinity between the passageways from the nearest main aisle to each exit.
(b) Adequate space to allow crew member(s) to assist in the evacuation of passengers shall be provided as follows:
(amended 2007/03/08)
- (1) Each assist space shall be a rectangle on the floor, of sufficient size to enable a crew member, standing erect, to effectively assist evacuees. The assist space shall not reduce the unobstructed width of the passageway below that required for the exit.
  (amended 2007/03/08)
- (2) For each Type A or Type B exit, assist space shall be provided at each side of the exit regardless of whether a means is required by 525.810(a).
  (amended 2007/03/08)
- (3) For each Type C, I or II exit installed in an aeroplane with seating for more than 80 passengers, an assist space shall be provided at one side of the passageway regardless of whether an assist means is required by 525.810(a).
  (amended 2007/03/08)
- (4) For each Type C, I or II exit, an assist space shall be provided at one side of the passageway if an assist means is required by 525.810(a).
  (amended 2007/03/08; no previous version)
- (5) For any tail cone exit that qualifies for 25 additional passenger seats under the provisions of 525.807(g)(9)(ii), an assist space shall be provided, if an assist means is required by 525.810(a).
  (amended 2007/03/08; no previous version)
- (6) There shall be a handle, or handles, at each assist space, located to enable the crew member to steady himself or herself:
  (amended 2007/03/08; no previous version)
  - (i) While manually activating the assist means (where applicable) and,
    (amended 2007/03/08; no previous version)
  - (ii) While assisting passengers during an evacuation.
    (amended 2007/03/08)
(c) The following must be provided for each Type III or Type IV exit:
- (1) There must be access from the nearest main aisle to each exit. In addition, for each Type III exit in an aeroplane that has a passenger seating configuration of 60 or more:
  - (i) Except as provided in paragraph (c)(1)(ii), the access must be provided by an unobstructed passageway that is at least 10 inches in width for interior arrangements in which the adjacent seat rows on the exit side of the aisle contain no more than two seats, or 20 inches in width for interior arrangements in which those rows contain three seats. The width of the passageway must be measured with adjacent seats adjusted to their most adverse position. The centreline of the required passageway width must not be displaced more than 5 inches horizontally from that of the exit.
  - (ii) In lieu of one 10 or 20-inch passageway, there may be two passageways, between seat rows only, that must be at least 6 inches in width and lead to an unobstructed space adjacent to each exit. (Adjacent exits must not share a common passageway.) The width of the passageways must be measured with adjacent seats adjusted to their most adverse position. The unobstructed space adjacent to the exit must extend vertically from the floor to the ceiling (or bottom of sidewall stowage bins), inboard from the exit for a distance not less than the width of the narrowest passenger seat installed on the aeroplane, and from the forward edge of the forward passageway to the aft edge of the aft passageway. The exit opening must be totally in the fore and aft bounds of the unobstructed space.
- (2) In addition to the access:
  - (i) For aeroplanes that have a passenger seating configuration of 20 or more, the projected opening of the exit provided must not be obstructed and there must be no interference in opening the exit by seats, berths, or other protrusions (including any seat back in the most adverse position) for a distance from that exit not less than the width of the narrowest passenger seat installed on the aeroplane.
  - (ii) or aeroplanes that have a passenger seating configuration of 19 or fewer, there may be minor obstructions in this region, if there are compensating factors to maintain the effectiveness of the exit.
- (3) For each Type III exit, regardless of the passenger capacity of the aeroplane in which it is installed, there must be placards that:
  - (i) Are readable by all persons seated adjacent to and facing a passageway to the exit;
  - (ii) Accurately state or illustrate the proper method of opening the exit, including the use of handholds; and
  - (iii) If the exit is a removable hatch, state the weight of the hatch and indicate an appropriate location to place the hatch after removal.
(d) If it is necessary to pass through a passageway between passenger compartments to reach any required emergency exit from any seat in the passenger cabin, the passageway must be unobstructed. However, curtains may be used if they allow free entry through the passageway.
(e) No door may be installed between any passenger seat that is occupiable for takeoff and landing and any passenger emergency exit, such that the door crosses any egress path (including aisles, cross aisles and passageways).
(amended 2007/03/08)
(f) If it is necessary to pass through a doorway separating any crew member seat (except those seats on the flight deck), occupiable for takeoff and landing, from any emergency exit, the door shall have a means to latch it in open position. The latching means shall be able to withstand the loads imposed upon it when the door is subjected to the ultimate inertia forces, relative to the surrounding structure, listed in 525.561(b).
(amended 2007/03/08)

(Change 525-3 (91-11-01))

(Change 525-5 (92-10-30))

(Change 525-8

525.815 Width of Aisle

The passenger aisle width at any point between seats must equal or exceed the values in the following table:

Passenger seating capacity	Minimum passenger aisle width (inches)
	Less than 25 in. from floor	25 in. and more from floor
10 or less 11 through 19 20 or more	12¹ 12 15	15 20 20
¹A narrower width not less than 9 inches may be approved when substantiated by tests found necessary by the Minister

525.817 Maximum Number of Seats Abreast

On aeroplanes having only one passenger aisle, no more than three seats abreast may be placed on each side of the aisle in any one row.

525.819 Lower Deck Service Compartments (Including Galleys)

For aeroplanes with a service compartment located below the main deck, which may be occupied during taxi or flight but not during take-off or landing, the following apply:

(a) There must be at least two emergency evacuation routes, one at each end of lower deck service compartment or two having sufficient separation within each compartment, which could be used by each occupant or the lower deck service compartment to rapidly evacuate to the main deck under normal and emergency lighting conditions. The routes must provide for the evacuation of incapacitated persons, with assistance. The use of the evacuation routes may not be dependent on any powered device. The routes must be designed to minimise the possibility of blockage which might result from fire, mechanical or structural failure, or persons standing on top of or against the escape routes. In the event the aeroplane's main power system or compartment main lighting system should fail, emergency illumination for each lower deck service compartment must be automatically provided.
(b) There must be a means for two-way voice communication between the flight deck and each lower deck service compartment, which remains available following loss of normal electrical power generating system.
(amended 2003/11/10)
(c) There must be an aural emergency alarm system, audible during normal and emergency conditions, to enable crew members on the flight deck and at each required floor level emergency exit to alert occupants of each lower deck service compartment of an emergency situation.
(d) There must be a means, readily detectable by occupants of each lower deck service compartment, that indicates when seat belts should be fastened.
(e) If a public address system is installed in the aeroplane, speakers must be provided in each lower deck service compartment.
(f) For each occupant permitted in a lower deck service compartment, there must be a forward or aft facing seat which meets the requirements of 525.785(d) and must be able to withstand maximum flight loads when occupied.
(amended 2003/11/10)
(g) For each powered lift system installed between a lower deck service compartment and the main deck for the carriage of persons or equipment, or both, the system must meet the following requirements:
- (1) Each lift control switch outside the lift, except emergency stop buttons, must be designed to prevent the activation of the lift if the lift door, or the hatch required by paragraph (g)(3) of this section, or both are open.
- (2) An emergency stop button, that when activated will immediately stop the lift, must be installed within the lift and at each entrance to the lift.
- (3) There must be a hatch capable of being used for evacuating persons from the lift that is openable from inside and outside the lift without tools, with the lift in any position.

525.820 Lavatory Doors

(amended 2007/03/08; no previous version)

All lavatory doors shall be designed to preclude anyone from becoming trapped inside the lavatory. If a locking mechanism is installed, it shall be capable of being unlocked from the outside without the aid of special tools.
(amended 2007/03/08; no previous version)

Ventilation and Heating

525.831 Ventilation

(a) Under normal operating conditions and in the event of any probable failure conditions of any system which would adversely affect the ventilating air, the ventilation system must be designed to provide a sufficient amount of uncontaminated air to enable the crew-members to perform their duties without undue discomfort or fatigue and to provide reasonable passenger comfort. For normal operating conditions, the ventilation system must be designed to provide each occupant with an airflow containing at least 0.55 pounds of fresh air per minute.
(b) Crew and passenger compartment air must be free from harmful or hazardous concentrations of gases or vapours. In meeting this requirement, the following apply:
- (1) Carbon monoxide concentrations in excess of one part in 20,000 parts of air are considered hazardous. For test purposes, any acceptable carbon monoxide detection method may be used.
- (2) Carbon dioxide concentration during flight must be shown not to exceed 0.5 percent by volume (sea level equivalent) in compartments normally occupied by passengers or crew members.
(c) There must be provisions made to ensure that the conditions prescribed in paragraph (b) of this section are met after reasonably probable failures or malfunctioning of the ventilating, heating, pressurisation, or other systems and equipment.
(d) If accumulation of hazardous quantities of smoke in the cockpit area is reasonably probable, smoke evacuation must be readily accomplished, starting with full pressurisation and without depressurising beyond safe limits.
(e) Except as provided in paragraph (f) of this section, means must be provided to enable the occupants of the following compartments and areas to control the temperature and quantity of ventilating air supplied to their compartment or area independently of the temperature and quantity of air supplied to other compartments and areas:
- (1) The flight crew compartment.
- (2) Crew member compartments and areas other than the flight crew compartment unless the crew member compartment or area is ventilated by air interchange with other compartments or areas under all operating conditions.
(f) Means to enable the flight crew to control the temperature and quantity of ventilating air supplied to the flight crew compartment independently of the temperature and quantity of ventilating air supplied to other compartments are not required if all of the following conditions are met:
- (1) The total volume of the flight crew and passenger compartments is 800 cubic feet or less.
- (2) The air inlets and passages for air to flow between flight crew and passenger compartments are arranged to provide compartment temperatures within 5 degrees F. of each other and adequate ventilation to occupants in both compartments.
- (3) The temperature and ventilation controls are accessible to the flight crew.
- (g) The exposure time at any given temperature must not exceed the values shown in the following graph after any improbable failure condition.

(Change 525-8)

525.832 Cabin Ozone Concentration

(a) The aeroplane cabin ozone concentration during flight must be shown not to exceed:
- (1) 0.25 parts per million by volume, sea level equivalent, at any time above flight level 320; and
- (2) 0.1 parts per million by volume, sea level equivalent, time-weighted average during any 3-hour interval above flight level 270.
(b) For the purpose of this section, "sea level equivalent" refers to conditions of 25°C and 760 millimetres of mercury pressure.
(c) Compliance with this section must be shown by analysis or tests based on aeroplane operational procedures and performance limitation, that demonstrate that either:
- (1) The aeroplane cannot be operated at an altitude which would result in cabin ozone concentrations exceeding the limits prescribed by paragraph (a) of this section; or
- (2) The aeroplane ventilation system, including any ozone control equipment, will maintain cabin ozone concentrations at or below the limits prescribed by paragraph (a) of this section.

525.833 Combustion Heating Systems

Combustion heaters must be approved.

(Change 525-3 (91-11-01))

Pressurisation

525.841 Pressurised Cabins

(a) Except as provided in paragraph (c) of this section, pressurised cabins and compartments to be occupied must be equipped to provide a cabin pressure altitude of not more than 8,000 feet under normal operating conditions. (effective 2024/04/05)
- (1) If certification for operation above 25,000 feet is requested, the aeroplane must be designed so that occupants will not be exposed to cabin pressure altitudes in excess of 15,000 feet after any probable failure condition in the pressurisation system except as provided in paragraph (c) of this section. (effective 2024/04/05)
- (2) The aeroplane must be designed so that occupants will not be exposed to a cabin pressure altitude that exceeds the following after decompression from any failure condition not shown to be extremely improbable:
  - (i) Twenty-five thousand (25,000) feet for more than 2 minutes; or
  - (ii) Forty thousand (40,000) feet for any duration.
- (3) Fuselage structure, engine and system failures are to be considered in evaluating the cabin decompression.
(b) Pressurised cabins must have at least the following valves, controls, and indicators for controlling cabin pressure:
- (1) Two pressure relief valves to automatically limit the positive pressure differential to a predetermined value at the maximum rate of flow delivered by the pressure source. The combined capacity of the relief valve must be large enough so that the failure of any one valve would not cause an appreciable rise in the pressure differential. The pressure differential is positive when the internal pressure is greater than the external.
- (2) Two reverse pressure differential relief valves (or their equivalents) to automatically prevent a negative pressure differential that would damage the structure. One valve is enough, however, if it is of a design that reasonably precludes its malfunctioning.
- (3) A means by which the pressure differential can be rapidly equalised.
- (4) An automatic or manual regulator for controlling the intake or exhaust airflow, or both, for maintaining the required internal pressures and airflow rates.
- (5) Instruments at the pilot or flight engineer station to show the pressure differential, the cabin pressure altitude, and the rate of change of the cabin pressure altitude.
- (6) Warning indication to the flight crew when the safe or pre-set pressure differential or cabin pressure altitude limit is exceeded. Appropriate warning markings on the cabin pressure differential indicator meet the warning requirement for pressure differential limits. An alert meets the warning requirement for cabin pressure altitude limits if it warns the flight crew when the cabin pressure altitude exceeds 10,000 feet, except as provided in paragraph (d) of this section. (effective 2024/04/05)
- (7) A warning placard at the pilot or flight engineer station if the structure is not designed for pressure differentials up to the maximum relief valve setting in combination with landing loads.
- (8) The pressure sensors necessary to meet the requirements of paragraphs (b)(5) and (b)(6) of this section and 525.1447(c), must be located and the sensing system designed so that, in the event of loss of cabin pressure in any passenger or crew compartment (including upper and lower lobe galleys), the warning and automatic presentation devices, required by those provisions, will be actuated without any delay that would significantly increase the hazards resulting from decompression.
(c) When operating into or out of airports with elevations at or above 8,000 feet, the cabin pressure altitude in pressurised cabins and occupied compartments may be up to, or greater than, the airport elevation by 2,000 feet, provided: (effective 2024/04/05)
- (1) In the event of probable failure conditions of the cabin pressurisation system, the cabin pressure altitude must not exceed 15,000 feet, or 2,000 feet above the airport elevation, whichever is higher; and (effective 2024/04/05)
- (2) The cabin pressurisation system is designed to minimize the time in flight that occupants may be exposed to cabin pressure altitudes exceeding 8,000 feet. (effective 2024/04/05)
(d) When operating into or out of airports with elevations at or above 8,000 feet, the cabin pressure high altitude warning alert may be provided at up to 15,000 feet, or 2,000 feet above the aeroplane’s maximum take-off and landing altitude, whichever is greater, provided: (effective 2024/04/05)
- (1) During landing, the change in cabin pressure high altitude warning alert may not occur before the start of descent into the high elevation airport and, following take-off, the cabin pressure high altitude warning alert must be reset to 10,000 feet before beginning cruise operation; (effective 2024/04/05)
- (2) Indication is provided to the flight crew that the cabin pressure high altitude warning alert has shifted above 10,000 feet cabin pressure altitude; and (effective 2024/04/05)
- (3) Either an alerting system is installed that notifies the flight crew members on flight deck duty when to don oxygen in accordance with the applicable operating regulations, or a limitation is provided in the aeroplane flight manual that requires the pilot flying the aeroplane to don oxygen when the cabin pressure altitude warning has shifted above 10,000 feet, and requires other flight crew members on flight deck duty to monitor the cabin pressure and utilize oxygen in accordance with the applicable operating regulations. (effective 2024/04/05)

(Change 525-8) and (Change 525-30)

525.843 Tests for Pressurised Cabins

(a) Strength Test. The complete pressurised cabin, including doors, windows, and valves, must be tested as a pressure vessel for the pressure differential specified in 525.365(d).
(b) Functional Tests. The following functional tests must be performed:
- (1) Tests of the functioning and capacity of the positive and negative pressure differential valves, and of the emergency release valve, to simulate the effects of closed regulator valves.
- (2) Tests of the pressurisation system to show proper functioning under each possible condition of pressure, temperature, and moisture, up to the maximum altitude for which certification is requested.
- (3) Flight tests, to show the performance of the pressure supply, pressure and flow regulators, indicators, and warning signals, in steady and stepped climbs and descents at rates corresponding to the maximum attainable within the operating limitations of the aeroplane, up to the maximum altitude for which certification is requested.
- (4) Tests of each door and emergency exit, to show that they operate properly after being subjected to the flight tests prescribed in subparagraph (3) of this paragraph.

Fire Protection

525.851 Fire Extinguishers

(a) Hand fire extinguishers.
- (1) The following minimum number of hand fire extinguishers must be conveniently located and evenly distributed in passenger compartments:

Passenger Capacity:	No. of Extinguishers
7 through 30 31 through 60 61 through 200 201 through 300 301 through 400 401 through 500 501 through 600 601 through 700	1 2 3 4 5 6 7 8

- (2) At least one hand fire extinguisher must be conveniently located in the pilot compartment.
- (3) At least one readily accessible hand fire extinguisher must be available for use in each Class A or Class B cargo or baggage compartment and in each Class E or Class F cargo or baggage compartment that is accessible to crew members in flight.
  (effective 2017/06/19)
- (4) At least one hand fire extinguisher must be located in, or readily accessible for use in, each galley located above or below the passenger compartment.
- (5) Each hand fire extinguisher must be approved.
- (6) At least one of the required fire extinguishers located in the passenger compartment of an aeroplane with a passenger capacity of at least 31 and not more than 60, and at least two of the fire extinguishers located in the passenger compartment of an aeroplane with a passenger capacity of 61 or more must contain Halon 1211 (bromochlorodifluoromethane CBrC₁F₂, or equivalent, as the extinguishing agent. The type of extinguishing agent used in any other extinguisher required by this section must be appropriate for the kinds of fires likely to occur where used.
- (7) The quantity of extinguishing agent used in each extinguisher required by this section must be appropriate for the kinds of fires likely to occur where used.
- (8) Each extinguisher intended for use in a personnel compartment must be designed to minimise the hazard of toxic gas concentration.
(b) Built-in Fire Extinguishers. If a built-in fire extinguisher is provided:
- (1) Each built-in fire extinguishing system must be installed so that:
  - (i) No extinguishing agent likely to enter personnel compartments will be hazardous to the occupants; and
  - (ii) No discharge of the extinguisher can cause structural damage.
- (2) The capacity of each required built in fire extinguishing system must be adequate for any fire likely to occur in that compartment where used, considering the volume of the compartment and the ventilation rate. The capacity of each system is adequate if there is sufficient quantity of agent to extinguish the fire or suppress the fire anywhere baggage or cargo is placed within the cargo compartment for the duration required to land and evacuate the aeroplane.
  (effective 2017/06/19)

(Change 525-3 (91-11-01))

525.853 Compartment Interiors

For each compartment occupied by the crew or passengers, the following apply:

(a) Materials (including finishes or decorative surfaces applied to the materials) must meet the applicable test criteria prescribed in Part I of Appendix F of this chapter or other approved equivalent methods.
(b) (Reserved)
(c) In addition to meeting the requirements of paragraph (a) of this section, seat cushions, except those on flight crew member seats, must meet the test requirements of Part II of Appendix F of this chapter, or other equivalent methods, regardless of the passenger capacity of the aeroplane.
(d) Except as provided in paragraph (e) of this section, the following interior components of aeroplanes with passenger capacities of 20 or more must also meet the test requirements of Parts IV and V of Appendix F of this chapter, or other approved equivalent methods, in addition to the flammability requirements prescribed in paragraph (a) of this section:
- (1) Interior ceiling and wall panels, other than lighting lenses and windows;
- (2) Partitions, other than transparent panels needed to enhance cabin safety;
- (3) Galley structure, including exposed surfaces of stowed carts and standard containers and the cavity walls that are exposed when a full complement of such carts or containers is not carried;
- (4) Large cabinets and cabin stowage compartments, other than underseat stowage compartments for stowing small items such as magazines and maps.
(e) The interiors of compartments, such as pilot compartments, galleys, lavatories, crew rest quarters, cabinets and stowage compartments, need not meet the standards of paragraph (d) of this section, provided the interiors of such compartments are isolated from the main passenger cabin by doors or equivalent means that would normally be closed during an emergency landing condition.
(f) Smoking is not to be allowed in lavatories. If smoking is allowed in any area occupied by the crew or passengers, an adequate number of self-contained, removable ashtrays shall be provided in designated smoking sections for all seated occupants.
(amended 2007/03/08)
(g) Regardless of whether smoking is allowed in any other part of the aeroplane, lavatories must have self-contained, removable ashtrays located conspicuously on or near the entry side of each lavatory door, except that one ashtray may serve more than one lavatory door if the ashtray can be seen readily from the cabin side of each lavatory served.
(h) Each receptacle used for the disposal of flammable waste material must be fully enclosed, constructed of at least fire resistant materials, and must contain fires likely to occur in it under normal use. The capability of the receptacle to contain those fires under all probable conditions of wear, misalignment, and ventilation expected in service must be demonstrated by test.

(Change 525-1 (87-01-01))

(Change 525-3 (91-11-01))

(Change 525-6 (93-12-30))

(Change 525-7 (96-09-30))

525.854 Lavatory Fire Protection

For aeroplanes with a passenger capacity of 20 or more:

(a) Each lavatory must be equipped with a smoke detector system or equivalent that provides a warning light in the cockpit, or provides a warning light or audible warning in the passenger cabin that would be readily detected by a flight attendant; and
(b) Each lavatory must be equipped with a built-in fire extinguisher for each disposal receptacle for towels, paper, or waste, located within the lavatory. The extinguisher must be designed to discharge automatically into each disposal receptacle upon occurrence of a fire in that receptacle.

(Change 525-3 (91-11-01))

525.855 Cargo and Baggage Compartments

For each cargo and baggage compartment, the following apply:
(amended 2007/03/08)

(a) The compartment must meet one of the class requirements of 525.857.
(b) Each of the following cargo or baggage compartments, as defined in section 525.857, must have a liner that is separate from, but may be attached to, the aeroplane structure:
(effective 2017/06/19)
- (1) any Class B through Class E cargo or baggage compartment; and
  (effective 2017/06/19)
- (2) any Class F cargo or baggage compartment, unless other means of containing a fire and protecting critical systems and structure are provided.
  (effective 2017/06/19)
(c) Ceiling and sidewall liner panels of Class C cargo or baggage compartments, and ceiling and sidewall liner panels in Class F cargo or baggage compartments, if installed to meet the requirements of (b)(2) of this section, must meet the test requirements of Part III of Appendix F of this chapter or other approved equivalent methods.
(effective 2017/06/19)
(d) All other materials used in the construction of the cargo or baggage compartment must meet the applicable test criteria prescribed in Part I of Appendix F of this chapter or other approved equivalent methods.
(e) No compartment must contain any controls, lines, equipment, or accessories whose damage or failure would affect safe operation, unless those items are protected so that:
(amended 2009/05/11)
- (1) They cannot be damaged by the movement of cargo in the compartment; and
- (2) Their breakage or failure will not create a fire hazard.
(f) There must be means to prevent cargo or baggage from interfering with the functioning of the fire-protective features of the compartment.
(g) Sources of heat within the compartment must be shielded and insulated to prevent igniting the cargo or baggage.
(h) Flight tests must be conducted to show compliance with the provisions of section 525.857 concerning:
- (1) Compartment accessibility;
- (2) The entries of hazardous quantities of smoke or extinguishing agent into compartments occupied by the crew or passengers; and
- (3) The dissipation of the extinguishing agent in all Class C compartments and, if applicable, in any Class F compartments.
  (effective 2017/06/19)
(i) During the above tests, it must be shown that no inadvertent operation of smoke or fire detectors in any compartment would occur as a result of fire contained in any other compartment, either during or after extinguishment, unless the extinguishing system floods each such compartment simultaneously.
(j) Cargo or baggage compartment electrical wiring interconnection system components must meet the requirements of 525.1721.
(amended 2009/05/11; no previous version)

(Change 525-1 (87-01-01))

(Change 525-3 (91-11-01))

(Change 525-8)

525.856 Thermal/Acoustic Insulation Materials

(amended 2004/06/08; no previous version)

(a) Thermal/acoustic insulation material installed in the fuselage shall meet the flame propagation test requirements of part VI of Appendix F to this chapter, or other approved equivalent test requirements. This requirement does not apply to "small parts," as defined in part I of Appendix F of this chapter.
(amended 2004/06/08; no previous version)
(b) For aeroplanes with a passenger capacity of 20 or greater, thermal/acoustic insulation materials (including the means of fastening the materials to the fuselage) installed in the lower half of the aeroplane fuselage shall meet the flame penetration resistance test requirements of part VII of Appendix F to this chapter, or other approved equivalent test requirements. This requirement does not apply to thermal/acoustic insulation installations that Transport Canada Civil Aviation finds would not contribute to fire penetration resistance.
(amended 2004/06/08; no previous version)

525.857 Cargo Compartment Classification

(a) Class A. Class A cargo or luggage compartment is one in which:
- (1) The presence of a fire would be easily discovered by a crew member while at his station; and
- (2) Each part of the compartment is easily accessible in flight.
(b) Class B. A Class B cargo or baggage compartment is one in which:
- (1) There is sufficient access in flight to enable a crew member, standing at any one access point and without stepping into the compartment, to extinguish a fire occurring in any part of the compartment using a hand fire extinguisher;
  (effective 2017/06/19)
- (2) When the access provisions are being used, no hazardous quantity of smoke, flames, or extinguishing agent, will enter any compartment occupied by the crew or passengers;
- (3) There is a separate approved smoke detector or fire detector system to give warning at the pilot or flight engineer station; and
- (4) (Reserved)
(c) Class C. A Class C cargo or baggage compartment is one not meeting the requirements for either a Class A or B compartment but in which:
- (1) There is a separate approved smoke detector or fire detector system to give warning at the pilot or flight engineer station;
- (2) There is an approved built-in fire extinguishing or suppression system controllable from the cockpit;
- (3) There are means to exclude hazardous quantities of smoke, flames, or extinguishing agent, from any compartment occupied by the crew or passengers;
- (4) There are means to control ventilation and drafts within the compartment so that the extinguishing agent used can control any fire that may start within the compartment; and
- (5) (Reserved)
(d) Removed and Reserved
(e) Class E. A Class E cargo compartment is one on aeroplanes used only for the carriage of cargo and in which:
- (1) (Reserved)
- (2) There is a separate approved smoke or fire detector system to give warning at the pilot or flight engineer station;
- (3) There are means to shut off the ventilating airflow to, or within, the compartment, and the controls for these means are accessible to the flight crew in the crew compartment;
- (4) There are means to exclude hazardous quantities of smoke, flames, or noxious gases, from the flight crew compartment; and
- (5) The required crew emergency exits are accessible under any cargo loading condition.
(f) Class F. A Class F cargo or baggage compartment must be located on the main deck and is one in which:
(effective 2017/06/19)
- (1) there is a separate approved smoke detector or fire detector system to give warning at the pilot or flight engineer station;
- (2) there are means to extinguish or control a fire without requiring a crew member to enter the compartment; and
- (3) there are means to exclude hazardous quantities of smoke, flames, or extinguishing agent from any compartment occupied by the crew or passengers.

(Change 525-1 (87-01-01))
(Change 525-8)

525.858 Cargo or Baggage Compartment Smoke or Fire Detection Systems

If certification with cargo or baggage compartment smoke or fire detection provisions is requested, the following must be met for each cargo or baggage compartment with those provisions:

(a) The detection system must provide a visual indication to the flight crew within one minute after the start of a fire.
(b) The system must be capable of detecting a fire at a temperature significantly below that at which the structural integrity of the aeroplane is substantially decreased.
(c) There must be means to allow the crew to check in flight, the functioning of each fire detector circuit.
(d) The effectiveness of the detection system must be shown for all approved operating configurations and conditions.

(Change 525-8)

525.859 Combustion Heater Fire Protection

(a) Combustion heater fire zones. The following combustion heater fire zones must be protected from fire in accordance with the applicable provisions of 525.1181 through 525.1191 and 525.1195 through 525.1203:
- (1) The region surrounding the heater, if this region contains any flammable fluid system components (excluding the heater fuel system), that could:
  - (i) Be damaged by heater malfunctioning; or
  - (ii) Allow flammable fluids or vapours to reach the heater in case of leakage.
- (2) The region surrounding the heater, if the heater fuel system has fittings that, if they leaked, would allow fuel or vapours to enter this region.
- (3) The part of the ventilating air passage that surrounds the combustion chamber. However, no fire extinguishment is required in cabin ventilating air passages.
(b) Ventilating air ducts. Each ventilating air duct passing through any fire zone must be fireproof. In addition:
- (1) Unless isolation is provided by fireproof valves or by equally effective means, the ventilating air duct downstream of each heater must be fireproof for a distance great enough to ensure that any fire originating in the heater can be contained in the duct; and
- (2) Each part of any ventilating duct passing through any region having a flammable fluid system must be constructed or isolated from that system so that the malfunctioning of any component of that system cannot introduce flammable fluids or vapours into the ventilating airstream.
(c) Combustion air ducts. Each combustion air duct must be fireproof for a distance great enough to prevent damage from backfiring or reverse flame propagation. In addition:
- (1) No combustion air duct may have a common opening with the ventilating airstream unless flames from backfires or reverse burning cannot enter the ventilating airstream under any operating condition, including reverse flow or malfunctioning of the heater or its associated components; and
- (2) No combustion air duct may restrict the prompt relief of any backfire that, if so restricted, could cause heater failure.
(d) Heater controls; general. Provision must be made to prevent the hazardous accumulation of water or ice on or in any heater control component, control system tubing, or safety control.
(e) Heater safety controls. For each combustion heater there must be the following safety control means:
- (1) Means independent of the components provided for the normal continuous control of air temperature, airflow, and fuel flow must be provided, for each heater, to automatically shut off the ignition and fuel supply to that heater at a point remote from that heater when any of the following occurs:
  - (i) The heat exchanger temperature exceeds safe limits.
  - (ii) The ventilating air temperature exceeds safe limits.
  - (iii) The combustion airflow becomes inadequate for safe operation.
  - (iv) The ventilating airflow becomes inadequate for safe operation.
- (2) The means of complying with subparagraph (1) of this paragraph for any individual heater must:
- (i) Be independent of components serving any other heater whose heat output is essential for safe operation; and
- (ii) Keep the heater off until restarted by the crew.
- (3) There must be means to warn the crew when any heater whose heat out-put is essential for safe operation has been shut off by the automatic means prescribed in subparagraph (1) of this paragraph.
(f) Air intakes. Each combustion and ventilating air intake must be located so that no flammable fluids or vapours can enter the heater system under any operating condition:
- (1) During normal operation; or
- (2) As a result of the malfunctioning of any other component.
(g) Heater exhaust. Heater exhaust systems must meet the provisions of 525.1121 and 525.1123. In addition, there must be provisions in the design of the heater exhaust system to safely expel the products of combustion to prevent the occurrence of:
- (1) Fuel leakage from the exhaust to surrounding compartments;
- (2) Exhaust gas impingement on surrounding equipment or structure;
- (3) Ignition of flammable fluids by the exhaust, if the exhaust is in a compartment containing flammable fluid lines; and
- (4) Restriction by the exhaust of the prompt relief of backfires that, if so restricted, could cause heater failure.
(h) Heater fuel systems. Each heater fuel system must meet each powerplant fuel system requirement affecting safe heater operation. Each heater fuel system component within the ventilating airstream must be protected by shrouds so that no leakage from those components can enter the ventilating airstream.
(i) Drains. There must be means to safely drain fuel that might accumulate within the combustion chamber or the heat exchanger. In addition:
- (1) Each part of any drain that operates at high temperatures must be protected in the same manner as heater exhausts; and
- (2) Each drain must be protected from hazardous ice accumulation under any operating condition.

525.863 Flammable Fluid Fire Protection

(a) In each area where flammable fluids or vapours might escape by leakage of a fluid system, there must be means to minimise the probability of ignition of the fluids and vapours, and the resultant hazards if ignition does occur.
(b) Compliance with paragraph (a) of this section must be shown by analysis or tests, and the following factors must be considered.
- (1) Possible sources and paths of fluid leakage, and means of detecting leakage.
- (2) Flammability characteristics of fluids, including effects of any combustible or absorbing materials.
- (3) Possible ignition sources, including electrical faults, overheating of equipment, and malfunctioning of protective devices.
- (4) Means available for controlling or extinguishing a fire, such as stopping flow of fluids, shutting down equipment, fireproof containment, or use of extinguishing agents.
- (5) Ability of aeroplane components that are critical to safety of flight to withstand fire and heat.
(c) If action by the flight crew is required to prevent or counteract a fluid fire (e.g. equipment shutdown or actuation of a fire extinguisher) quick acting means must be provided to alert the crew.
(d) Each area where flammable fluids or vapours might escape by leakage of a fluid system must be identified and defined.

525.865 Fire Protection of Flight Controls, Engine Mounts, and Other Flight Structure

Essential flight controls, engine mounts, and other flight structures located in designated fire zones or in adjacent areas which would be subjected to the effects of fire in the fire zone must be constructed of fireproof material or shielded so that they are capable of withstanding the effects of fire.

525.867 Fire Protection: Other Components

(a) Surfaces to the rear of the nacelles, within one nacelle diameter of the nacelle centreline, must be at least fire-resistant.
(b) Paragraph (a) of this section does not apply to tail surfaces to the rear of the nacelles that could not be readily affected by heat, flames or sparks coming from a designated fire zone or engine compartment of any nacelle.

525.869 Fire Protection: Systems

(a) Electrical system components:
- (1) Components of the electrical system must meet the applicable fire and smoke protection requirements of 525.831(c) and 525.863.
- (2) Equipment that is located in designated fire zones and is used during emergency procedures must be at least fire-resistant.
  (amended 2009/05/11)
- (3) EWIS components must meet the requirements of 525.1713.
  (amended 2009/05/11)
(b) Each vacuum air system line and fitting on the discharge side of the pump that might contain flammable vapours or fluids must meet the requirements of 525.1183 if the line or fitting is in a designated fire zone. Other vacuum air systems components in designated fire zones must be at least fire resistant.
(c) Oxygen equipment and lines must:
- (1) Not be located in any designated fire zone,
- (2) Be protected from heat that may be generated in, or escape from, any designated fire zone, and
- (3) Be installed so that escaping oxygen cannot cause ignition of grease, fluid, or vapour accumulations that are present in normal operation or as a result of failure of malfunction of any system.

(Change 525-3 (91-11-01))

Miscellaneous

525.871 Levelling Means

There must be means for determining when the aeroplane is in a level position on the ground.

525.875 Reinforcement Near Propellers

(a) Each part of the aeroplane near the propeller tips must be strong and stiff enough to withstand the effects of the induced vibration and of ice thrown from the propeller.
(b) No window may be near the propeller tips unless it can withstand the most severe ice impact likely to occur.

525.899 Electrical Bonding and Protection Against Static Electricity

(amended 2009/05/11; no previous version)

(a) Electrical bonding and protection against static electricity must be designed to minimize accumulation of electrostatic charge that would cause:
(amended 2009/05/11; no previous version)
- (1) Human injury from electrical shock,
  (amended 2009/05/11; no previous version)
- (2) Ignition of flammable vapors, or
  (amended 2009/05/11; no previous version)
- (3) Interference with installed electrical/electronic equipment.
  (amended 2009/05/11; no previous version)
(b) Compliance with paragraph (a) of this section may be shown by:
(amended 2009/05/11; no previous version)
- (1) Bonding the components properly to the airframe; or
  (amended 2009/05/11; no previous version)
- (2) Incorporating other acceptable means to dissipate the static charge so as not to endanger the aeroplane, personnel, or operation of the installed electrical/electronic systems.
  (amended 2009/05/11; no previous version)

Airworthiness Chapter 525 Subchapter D - Design and Construction - Canadian Aviation Regulations (CARs)

Subchapters

Appendices

Subchapter D - Design and Construction

525.601 General

525.603 Materials

525.605 Fabrication Methods

525.607 Fasteners

525.609 Protection of Structure

525.611 Accessibility Provisions

525.613 Material Strength Properties and Material Design Values (amended 2003/11/26)

525.619 Special Factors

525.621 Casting Factors

525.623 Bearing Factors

525.625 Fitting Factors

525.629 Aeroelastic Stability Requirements

525.631 Bird Strike Damage

Control Surfaces

525.651 Proof of Strength

525.655 Installation

525.657 Hinges

Control Systems

525.671 General

525.672 Stability Augmentation and Automatic and Power-Operated Systems

525.675 Stops

525.677 Trim Systems

525.679 Control System Gust Locks

525.681 Limit Load Static Tests

525.683 Operation Tests (effective 2019/11/01)

525.685 Control System Details

525.689 Cable Systems

525.693 Joints

525.697 Lift and Drag Devices, Controls

525.699 Lift and Drag Device Indicator

525.701 Flap and Slat Interconnection

525.703 Take-off Warning System

Landing Gear

525.721 General (effective 2019/11/01)

525.723 Shock Absorption Tests

525.725 (Reserved)

525.727 (Reserved)

525.729 Retracting Mechanism

525.731 Wheels

525.733 Tires

525.735 Brakes and Braking Systems

525.737 Skis

Floats and Hulls

525.751 Main Float Buoyancy

525.753 Main Float Design

525.755 Hulls

Personnel and Cargo Accommodations

525.771 Pilot Compartment

525.772 Pilot Compartment Doors

525.773 Pilot Compartment View

525.775 Windshields and Windows

525.777 Cockpit Controls

525.779 Motion and Effect of Cockpit Controls

525.781 Cockpit Control Knob Shape

525.783 Fuselage Doors (amended 2007/03/08)

525.785 Seats, Berths, Safety Belts, and Harnesses

525.787 Stowage Compartments

525.789 Retention of Items of Mass in Passenger and Crew Compartments and Galleys

525.791 Passenger Information Signs and Placards

525.793 Floor Surfaces

525.794 Reserved

525.795 Security Considerations

Emergency Provisions

525.801 Ditching

525.803 Emergency Evacuation

525.807 Emergency Exits

525.809 Emergency Exit Arrangement

525.810 Emergency Egress Assist Means and Escape Routes

525.811 Emergency Exit Marking

525.812 Emergency Lighting

525.813 Emergency Exit Access

525.815 Width of Aisle

525.817 Maximum Number of Seats Abreast

525.819 Lower Deck Service Compartments (Including Galleys)

525.820 Lavatory Doors

Ventilation and Heating

525.613 Material Strength Properties and Material Design Values
(amended 2003/11/26)

525.683 Operation Tests
(effective 2019/11/01)

525.721 General
(effective 2019/11/01)

525.783 Fuselage Doors
(amended 2007/03/08)