Maintenance and Manufacturing Staff Instructions (MSI) No. 65

1. Purpose

1.1 The purpose of this Instruction, is to provide information to Civil Aviation Safety Inspectors regarding the subject of aircraft seat back break-over.

2. References

2.1 Airworthiness Manual (AWM) 525.785 (j): Seats, Berths, Safety Belts, and Harnesses

2.2 Federal Aviation Administration (FAA) Advisory Circular AC 25-17, Transport Airplane Cabin Interiors Crashworthiness Handbook, July 15, 1991

2.3 Technical Standard Order (TSO) - C39b, Aircraft Seats and Berths

2.4 Technical Standard Order (TSO) - C127a, Rotorcraft, Transport Airplane, And Normal And Utility Airplane Seating Systems

2.5 FAA Order 8300.10; Flight Standards Information Bulletin (FSIB) for Airworthiness (FSAW); FSAW 95-03: "Seat Back Break-over"

3. History

3.1 The certification requirement for a seat back in an aisle position to have a built-in resistance from breaking over forward, is found in AWM 525.785 (j), which states: "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."

3.2 Aircraft seats are designed to meet or exceed the minimum performance standards of TSO-C39b and TSO-C127a. These TSOs describe the acceptable standards for seat design, which are required as part of the aircraft certification basis.

3.3 FAA AC: 25-17, Transport Airplane Cabin Interiors Crashworthiness Handbook, July 15, 1991; page 201: "(d) If the seat backs do not have a firm hand hold, there must be a hand grip or rail along each aisle to enable the occupants to steady themselves while using the aisles in moderately rough air." Guidance: Page 204, "(6) Paragraph (d) The seat back may serve as a firm hand hold. Since most seats are capable of breaking over, the break-over load must be adequate to be considered firm. A load of 25 pounds minimum, acting horizontally, is considered adequate when applied at the top center of the seat back. (See paragraph 411b (8) for maximum break-over force.)

3.4 Most operators test and adjust the seat back break-over friction at 'C' check (or equivalent interval) when seats are in the overhaul shop.

4. Background

4.1 Conflicting individual and regional interpretations of the listed standards (in paragraph 2 - References) describing seat back break-over has caused confusion on how it is to be dealt with, in an operators scheduled maintenance program.

4.2 It is Transport Canada Civil Aviation's (TCCA's) position that:

1. The aircraft type certificate holder will have in place a maintenance task procedure for seats, that have a seat back break-over feature; and,
2. Seats immediately forward of / and at emergency exit rows shall not have a seat back break-over feature, since this could block egress in an emergency situation.

4.3 Seat configurations and features can include:

1. Aircraft passenger seats equipped with a break-over feature, wherein the seat back folds fully forward;
2. Seat models that move to a position of 15^o forward from a vertical position to provide an easier entry / exit for passengers;
3. Seat models (more commonly types with rigid backs) developed to meet 16g crash force requirements which cannot be moved forward without a special tool; or,
4. Seat models that have no seat back break-over feature.

5. Policy Statement

5.1 TCCA has adopted the provisions of FAA AC 25-17 as stated: "A load of 25 pounds minimum, acting horizontally, is considered adequate when applied at the top center of the seat back."

5.2 Civil Aviation Safety Inspectors with operator oversight should ensure that there is a procedure in the operator's maintenance schedule for verification of the seat back break-over as specified in the appropriate Component Maintenance Manual / Aircraft Maintenance Manual (CMM/AMM).

Note: Where the Instructions for Continued Airworthiness (ICA) have been found inadequate for this task, it is requested that the Inspector inform the Aircraft Evaluation Group (AARPG) of the inadequacy.

5.3 During routine ramp surveillance activities if seat back break-over resistance is in question, inspectors should expedite corrective action with the operator, without detaining the aircraft from its scheduled operations.

5.4 When conducting ramp surveillance, Civil Aviation Safety Inspectors are to ensure that the proper reporting procedures, which have been outlined in Maintenance and Manufacturing Staff Instruction (MSI) No. 6 - Ramp Surveillance, are adhered to.

6. Effective date

6.1 This instruction comes into effect on the date of issue.

7. HQ Contact

7.1 The responsible officer indicated below may be contacted for information regarding this MSI:

Superintendent, Aircraft Evaluation (AARPG)
Aircraft Maintenance & Manufacturing
Phone: (613) 952-4384
Facsimile: (613) 952-3298

D.B. Sherritt
Director,
Maintenance and Manufacturing