Aircraft Certification Staff Instruction (ACSI) No. 55 Issue 2

Aircraft Certification Staff Instruction (ACSI)

Subject: SHROUD TYPE CABIN HEATERS

1.0 INTRODUCTION

It was found that the airworthiness requirements for these installations were not well defined, thus causing varied interpretations of the FAR's. Accordingly, this Airworthiness Staff Instruction has been generated to provide for uniform application of the appropriate standards.

The compliance requirements shall be in a checklist format as shown at Appendix A and are based on the Airworthiness Manual Chapter 527 (Normal Category Rotorcraft). The compliance checklist may be modified to suit each particular application.

For reference purposes, a CAR 6 equivalence to the Airworthiness Manual Chapter 527 has been added as Appendix B.

2.0 PURPOSE

This Airworthiness Staff Instruction provides guidance to the Regional Airworthiness Engineers for an acceptable means by which Shroud Type Cabin Heaters may be approved in rotorcraft installations.

This ASI has been reissued to correct erroneous reference made to applicable airworthiness requirements. Changes are indicated by a vertical line adjacent to the left margin.

3.0 REFERENCE MATERIAL

• 4.1 Airworthiness Manual Chapter 527
• 4.2 Airworthiness Manual Chapter 529 (if applicable)
• 4.3 A.S.I. No.22 Supplementary Type Approval/Type Certificate Procedures
• 4.4 Applicable Type Approval

4.0 PROCEDURE

4.1 General

For an applicant requesting Supplemental Type Approval, Limited STA or "one-off mod" the procedure as detailed in Airworthiness Staff Instruction No. 22 (Supplementary Type Approval/Certificate procedure) shall be followed in addition to those outlined in this document.

4.2 Compliance Substantiation

The method of substantiation for each compliance item shall be by test, analysis, or inspection and shall be identified by the symbols "T", "A", and "I", respectively, on the compliance checklist.

The type of substantiation for each item shall be established at the start of the program. It may be determined that certain requirements on the compliance checklist are not applicable. Such items shall be identified and their exclusion justified. Similarly, should the applicant request an alleviation of requirement, the item shall be identified and accompanied by a justification note.

The tests and analyses shall be substantiated by reports detailing the methods of compliance and be identified on the checklist. The inspection items shall be supported by drawings, including installation drawing.

The approval shall then be shown against each item once requirements are satisfied.

It should be ensured that the applicant understands the compliance items including any Additional Airworthiness Requirements.

4.3 Compliance Review

Clarification of the following items in the compliance checklist is deemed necessary to show the intent of the requirements. The remaining checklist items are considered self-explanatory.

Item 18: 527.831 — Ventilation

Item 19: 527.853 (A) — Compartment Interiors

To prevent possibility of carbon monoxide (CO) emissions with this type of heater system, the installation of CO detectors is mandatory to satisfy Item 18. AlSo, should the plumbing be exposed to high heat or flame, no noxious gases should be transmitted to the cockpit via the plumbing due to material degradation. Furthermore, the plumbing material should be "flash resistant" if exposed to direct flame.

Item 21: 527.861 — Fire Protection of Structure, Controls and other Parts

To allow time to activate the Emergency Shut off Valve and turn off the shroud heater system.

Item 24: 527.1041 — Cooling - General

Item 25: 527.1043 — Cooling Tests

Item 26: 527.1045 — Cooling Test Procedures

While exhaust gas temperatures may remain unchanged with the addition of a shroud heater, alteration of the heat rejection rate is possible and may cause a temperature redistribution in the casing.

A temperature rise and the possible formation of hot spots would be detrimental to the engine and eventually affect the service life.

It is also possible that the shroud may decrease the . casing temperature which would also affect the engine and its operation.

The following temperature survey is recommended as a means of compliance:

1. Shroud Installed:
   • Heater On
   • Heater Off
2. Shroud Removed

Suitable test conditions for such a survey would be in hover, rearward flight, climb and takeoff.

To demonstrate that Flight Manual limitations are not exceeded and that no maximum temperature at which removal of the shroud heater is necessary, a hot day test shall be done.

Further, to demonstrate that the shroud does not abnormally cool the casing, a cold weather test is advisable.

Should the survey results be unacceptable to Transport Canada, applicant may contact the engine manufacturer to seek their opinion.

While the applicant is not required to receive consent from the manufacturer for such a modification, the applicant's standing would be better should his product be endorsed.

Item 30: 527.1193 — Cowling and Engine Compartment Covering

This paragraph covers any change to the cowling for any optional equipment (i.e.: winter cowlings).

Item 32: 527.1309(b) — Equipment, Systems and Installations (Hazards)

If a fan is used, rotor burst data should be submitted for any high speed fan. Also an explosive proof test of the fan motor would be required for an installation in an area that can be contaminated by explosive fumes.

Original signed by:

James A. Torck
Director, Airworthiness Branch

APPENDIX "A"

SHROUD TYPE CABIN HEATERS COMPLIANCE CHECKLIST

ITEM	REQUIREMENTS	SUBJECT	SUBSTANTIATION		APPROVAL
			TYPE(*)	DOCUMENTATION
1	527.301	(A), (B), (C) Loads
2	527.303	Factors of Safety
3	527.307	(A) Proof of Structure
4	527.321	Flight Loads General
5	527.337	Limit Manoeuvering Load Factor
6	527.341	Gust Loads (If Applicable)
7	527.561	(B)(3) & (C) General
8	527.601	Design
9	527.603	Materials
10	527.605	Fabrication Methods
11	527.321	Flight Loads General
12	527.609	Protection of Structure
13	527.611	Inspection Provisions
14	527.613	Material strength Properties and Design Values
15	527.623	Bearing Factors (If Applicable)
16	527.625	Fitting Factors
17	527.671	Control System - General
18	527.831	(A) & (B) Ventilation
19	527.853	(A) Compartment Interiors
20	527.859	(A) & (B) Heating Systems
21	527.861	Fire Protection of Structure, Controls and Other Parts
22	527.863	Flammable Fluid Fire Protection
23	527.901	Engine Installation
24	527.1041	Cooling - General
25	527.1043	Cooling Tests
26	527.1045	Cooling Test Procedures
27	527.1121	Exhaust System - General
28	527.1123	Exhaust Piping
29	527.1191	(A),(D),(E),(F) Firewalls
30	527.1193	Cowling & Engine Compartment Covering
31	527.1301	(A),(B),(C),(D) Function and Installation
32	527.1309	(b) Equipment, System & Installations Hazards
33	527.1351	(A)(1)&(2) Electrical System and Equipment - General
34	527.1351	Circuit Protective Devices
35	527.1357	Electric Cables
36	527.1365	Switches
37	527.1529	Instruction for Continued Airworthiness
38	527.1541	Markings & Placards General
39	527.1555	(A)&(D)(2) Control Markings
40	527.1559	Limitations Placard (If Applicable)
41	527.1581	Rotorcraft Flight Manual - General
42	527.1583	Operating Limitations
43	527.1585	Operating Procedures
44	527.1587	Performance Information
45	Applicable Addition Airworthiness Requirements/Special Conditions (Review of Type Approval or Type Certificate)

NOTES

* Denoted by:

• "T" (Test)
• "A" (Analysis)
• "I" (Inspection)

APPENDIX "B"

SHROUD TYPE CABIN HEATERS CAR 6 EQUIVALENCE

ITEM	REQUIREMENTS	SUBJECT	CAR 6
1	527.301	(A), (B), (C), Loads	6.200 (A)
2	527.303	Factor of Safety	6.200 (B)
3	527.307	(A) Proof of Structure	6.202
4	527.321	Flight Loads General	6.210
5	527.337	Limit Maneuvering Load Factor	6.212
6	527.341	Gust Loads (If applicable)	6.213
7	527.561	(B)(3) & (C) General	6.260
8	527.601	Design	6.300
9	527.603	Materials	6.301
10	527.605	Fabrication Methods	6.302
11	527.607	Fasteners	6.303
12	527.609	Protection of Structure	6.304
13	527.611	Inspection Provisions	6.305
14	527.613	Material Strength Properties and Design Values	6.306
15	527.623	Bearing Factors (If Applicable)	6.307 (C)
16	527.625	Fitting Factors	6.307 (D)
17	527.671	Control Systems - General	6.320
18	527.831	(A) & (B) Ventilation	6.358
19	527.853	(A) Compartment Interiors	6.381
20	527.859	(A) & (b) Heating Systems	6.383
21	527.861	Fire Protection of Structure, Controls and Other Parts	6.384
22	527.863	Flammable Fluid Fire Protection	5555
23	527.901	Engine Installation	6.402
24	527.1041	Cooling - General	6.450
25	527.1043	Cooling Tests	6.451
26	527.1045	Cooling Test Procedure	5555
27	527.1121	Exhaust System - General	6.460
28	527.1123	Exhaust Piping	6.463
29	527.1191	(A),(D),(E),(F) Firewalls	6.483
30	527.1193	Cowling & Engine Compartment Covering	6.484
31	527.1301	(A), (B), (C), (D) Function and Installation	6.6006.601
32	527.1309	(b) Equipment, Systems & Installations (Hazards)	6.620 (A)
33	527.1351	(A)(1) & (2)Electrical Systems and Equipment - General	6.6206.6216.622
34	527.1357	Circuit Protective Devices	6.625
35	527.1365	Electric Cables	6.627
36	527.1367	Switches	6.628
37	527.1529	Instructions for Continued Airworthiness	6.719
38	527.1541	Markings & Placards General	6.730
39	527.1555	(A) & (D)(2) Control Markings	6.737
40	527.1559	Limitations Placard (If Applicable)	6.638 (D)
41	527.1581	Rotorcraft Flight Manual - General	6.740
42	527.1583	Operating Limitations	6.741
43	527.1585	Operating Procedures	6.742
44	527.1587	Performance Information	6.743
45	Applicable Additional Airworthiness Requirements/Special Conditions		5555

Note: 5555 - denotes that requirement is not in CAR 6