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

ACSI No.: 55
Issue No.:  2
Issue Date:  1989-11-14
AARD File:  5009-3-55

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

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