REPORT #:

25370105

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01-MAY-12

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This document is the property of Field Aviation Company Inc., an Alberta corporation. By accepting this document for 

reference, the recipient agrees to hold Field Aviation Company Inc. harmless from any liabilities arising from the use or 

misuse of this document or the information contained therein. Duplication, disclosure to others or use for manufacturing 

purposes is not authorized without the prior written consent of Field Aviation Company Inc.

DESIGN COMPLIANCE ITEMS

FAA SUPPLEMENT

AUXILIARY FUEL SYSTEM

BOMBARDIER DHC-8 100/200/300 SERIES
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LOG OF REVISIONS

Rev. Date Description of Revision Prepared Checked Approved

IR 01-May-12 Initial Release M. Hales C. Marsetti W. Sprigg
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TABLE OF CONTENTS

1.0 INTRODUCTION............................................................................................................................ 4

1.1 PURPOSE............................................................................................................................... 4

1.2 SCOPE.................................................................................................................................... 4

1.3 APPLICABLE REQUIREMENTS ............................................................................................ 4

1.4 DESCRIPTION ........................................................................................................................ 4

1.5 ABBREVIATIONS ................................................................................................................... 4

2.0 COMPLIANCE STATEMENT MATRIX.......................................................................................... 5

APPENDIX A

APPENDIX B

APPENDIX C
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1.0 INTRODUCTION 

1.1 PURPOSE 

Field Aviation is seeking regulatory approval in the form of a Supplementary Type Certificate 

(STC) for the auxiliary fuel system for the DHC-8 Series 100, 200 & 300 aircraft.

1.2 SCOPE

This report provides statements of compliance against regulatory requirements.

The scope of this report includes structural, mechanical, electrical, and systems drawings and 

reports that are relevant to the compliance with FAA paragraphs listed below.

For clarification of the regulatory requirements and associated means of compliance, review the 

Compliance Program, Field Aviation Report 25370101.

1.3 APPLICABLE REQUIREMENTS

The applicable basis of certification, aircraft type approval and regulatory requirements are 

detailed in Field Aviation Report 25370100.

1.4 DESCRIPTION

For a detail description of the auxiliary fuel tank system refer to Field Aviation Engineering 

Report 20133.

1.5 ABBREVIATIONS

N/A Not Applicable

OEM Original Equipment Manufacturer

STC Supplementary Type Certificate
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2.0 COMPLIANCE STATEMENT MATRIX

AIRWORTHINESS 

REQUIREMENTS SUBJECT

Compliance

Statement Reference

FAA PARAGRAPH CERTIFICATION SPECIFICATION

SUBPART E - POWERPLANT

25.981 (a) Fuel Tank Ignition Prevention

Compliant. Refer to Safety Assessment Table and Fault 

Tree Diagram

Refer to 

25370105, 

Appendix A & 

C

25.981 (a)(1) Compliant. The minimum auto-ignition temperature for the 

fuels listed on the aircraft’s Type Certificate (Jet A, A-1, JP4, JP-5, JP-8 & Jet B) is 410oF. Refer to Safety 

Assessment Table.

Refer to 

25370105, 

Appendix A

25.981 (a)(2)

Compliant. Refer to Safety Assessment Table and Fault 

Tree Diagram

Refer to 

25370105, 

Appendix A & 

C

25.981 (a)(3)

Compliant to maximum extent possible. Refer to Safety 

Assessment Table and Fault Tree Diagram.

Refer to 

25370105, 

Appendix A & 

C

25.981 (b)(1) Compliant.

The DHC-8-200 is a high wing, subsonic aircraft primarily 

constructed of aluminum. The conventional, all aluminum 

and uninsulated wings contain integral fuel tanks and can 

carry Jet A, Jet A-1, JP-4, JP-5, JP-8 or Jet B fuel. The 

tanks are equalized with the external environment pressure 

via venting. Appendix A of this report contains a list of all 

internal and external heat sources. Being part of the wing, 

the tank is part of a large aerodynamic surface that is 

exposed to outside air. The Auxiliary tank ratio of surface 

area to fuel volume is 1.26 which exceeds the ratio of 1.0 

as specified in FAA Advisory Circular AC 25.981-2A 

(Section 10). By Design Auxiliary Fuel System bottom 

feeds both the Auxiliary and Main tanks and all tanks are 

vented to atmosphere.

25.981 (b)(2) N/A. Auxiliary tanks are not located within the fuselage 

contour.

25.981 (b)(3)(i) Compliant.

The DHC-8-200 is a high wing, subsonic aircraft primarily 

constructed of aluminum. The conventional, all aluminum 

and uninsulated wings contain integral fuel tanks and can 

carry Jet A, Jet A-1 or Jet B fuel. The tanks are equalized 

with the external environment pressure via venting.

25.981 b(3)(ii) Compliant

Appendix A of this report contains a list of all internal and

external heat sources. Being part of the wing, the tank is 

part of a large aerodynamic surface that is exposed to 

outside air. The Auxiliary tank ratio of surface area to fuel 

volume is 1.26 which exceeds the ratio of 1.0 as specified 

in FAA Advisory Circular AC 25.981-2A (Section 10). By 

Design Auxiliary Fuel System bottom feeds both the 

Auxiliary and Main tanks and all tanks are vented to 

atmosphere

Refer to 

25370105, 

Appendix A 

25.981 b(3)(iii) N/A. 

Auxiliary Tank system does not feed fuel directly into the 

engines

25.981 (c) Paragraph (b) applies
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AIRWORTHINESS 

REQUIREMENTS SUBJECT

Compliance

Statement Reference

25.981(d) Compliant. Inspection Procedures defined in Maintenance 

Manual Supplements

MMS20452 & 

25370111

SPECIAL CONDITION

26.11 Enhanced Airworthiness Program for Airplane 

Systems - ICA on EWIS

Compliant. EWIS Analysis and Task Reports 25370110 & 

25370111 are provided as the method of compliance with 

this paragraph

25370110/

25370111
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APPENDIX A - SAFETY ASSESSMENT OF AUXILIARY FUEL TANK

1. Compliance Statements regarding HIRF, Indirect Effects of Lightning & 

Single Point Ignition (Ref, Advisory Circular 25.981-1C)

1) Fuel System Wiring Harness Protection External to the Tank – HIRF 

Method A - One Level of Safety Mitigation

 Wire Harness Routing Drawings

 Drawing note stipulating the requirement for separate routing.

Method B - Two Levels of Safety Mitigation

 Double Shielding of Fuel Tank Wiring harnesses

Method C - One Level of Safety Mitigation

 Transient Protection – Solid State devices, example – Transorb

Method D - One Level of Safety Mitigation

 Airframe Electrical Field Attenuation – (-20 db) protection afforded to areas 

completely enclosed within metallic structure.

Note:

ICA must include periodic shield continuity testing as part of interval inspection 

criteria.

2) Powered Components Within a Tank - HIRF

Method A - Two Levels of Safety Mitigation

 Component Bonding – Redundant Paths

Method B - One Level of Safety Mitigation

 Wire Conductor Shielding

Method C - One Level of Safety Mitigation

 Component internal construction – Electrical/ Fuel/ Vapor isolation example 

Explosion proofing, Vacuum isolation.

Method D - One Level of Safety Mitigation

 Airframe Electrical Field Attenuation – (-20 db) protection afforded to areas 

completely enclosed within metallic structure.

Method E - One Level of Safety Mitigation

 Transient Protection – Solid State devices, example - Transorb
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3) Non-Powered Components within a Tank - HIRF

Method A – 2 levels of Safety Mitigation

 Component Bonding – Redundant Paths, example, bonding jumpers 

connected to adjacent structure

Method B – One Level of Safety Mitigation

 Direct Component Bonding – Structural Contact

Method C - One Level of Safety Mitigation

 Airframe Electrical Field Attenuation – (-20 db) protection afforded to areas 

completely enclosed within metallic structure.

4) Fuel System Wiring Harness Protection External to the Tank – Indirect 

Effects of Lightning

Method A - One Level of Safety Mitigation

 Wire Harness Routing Drawings

 Drawing note stipulating the requirement for separate routing.

Method B - Two Levels of Safety Mitigation

 Double Shielding of Fuel Tank Wiring harnesses

Method C - One Level of Safety Mitigation

 Transient Protection – Solid State devices, example – Transorb

Note:

ICA must include periodic shield continuity testing as part of interval inspection 

criteria.

5) Powered Components Within a Tank – Indirect Effects of Lightning

Method A - Two Levels of Safety Mitigation

 Component Bonding – Redundant Paths

Method B - One Level of Safety Mitigation

 Wire Conductor Shielding

Method C - One Level of Safety Mitigation

 Component internal construction – Electrical/ Fuel/ Vapor isolation example 

Explosion proofing, Vacuum isolation.

Method D - One Level of Safety Mitigation

 Transient Protection – Solid State devices, example - Transorb
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DATE:

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6) Non-Powered Components within a Tank Tank – Indirect Effects of 

Lightning

Method A – Two levels of Safety Mitigation

 Component Bonding – Redundant Paths, example, bonding jumpers 

connected to adjacent structure

Method B – One Level of Safety Mitigation

 Direct Component Bonding – Structural Contact

7) Powered Fuel System Components within a Tank - Single Point Ignition 

Failure Protection

Method A - One Level of Safety Mitigation

 Internal wire element conductors – insulation jacket

Method B - One1 Level of Safety Mitigation

 Non conductive flexible outer cable sheath

Method C - One Level of Safety Mitigation

 Component internal construction – Electrical/ Fuel/ Vapor isolation 

Method D - One Level of Safety Mitigation

 Wire Conductor Shielding

Method E - One Level of Safety Mitigation

 Transient Protection – Solid State devices, example - Transorb






REPORT #:

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DATE:

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APPENDIX B

Heat Transfer Analysis – Impact of ACM Bleed Air Pipe on Auxiliary Fuel Tank

The following diagram represents the situation being analyzed:

The situation can be analyzed as a composite wall and represented as follows:

R1

ΔT1

R2

ΔT2

R3

ΔT3

R4

ΔT4

R5

ΔT5
REPORT #:

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It is necessary t determine T6 to evaluate the potential inner surface temperature on the front spar. 

Doing so will allow a fuel ignition risk assessment to be made as a result of the heat generated by the 

ACM bleed air duct on the proximity of the fuel tank.

The analysis was conducted using the following assumptions:

1. An over-temperature switch will stop the supply of bleed air should it exceed 560°F (567K) 

therefore this is the maximum temperature that the volume will be subjected to. TACM = 567K

2. The fuel will be in a heated state equal to the maximum temperature of the aircraft of 54°C 

(317K), TFUEL=317K

3. The local cross section (A) of 1m2

4. k for air is 0.025 W/mK

 ∑ 

 

 where 

 

 

L is the local width of the section

k is the conduction coefficient of the material

R1 = 1.847x10-5 K/W

R2 = 0.305 K/W

R3 = 3.814x10-6 K/W

R4 = 0.864 K/W

R5 = 1.375x10-5 K/W

R = 1.205 K/W

It is then required to determine the total energy transferred as heat (Q) through the section:

 

 

 

where = 259K

 

 

 

 

⁄

 

Therefore:

 

Since R1, R3 and R5 are very small, it is assumed that T2=T1, T4=T3 & T6=T5 and ΔT1=ΔT3 =ΔT5 = 0.

ΔT2 = 215 W x 0.305 K/W = 66K

ΔT4 = 215 W x 0.864 K/W = 186K

Therefore, T6 = TACM - ΔT2 - ΔT4 = 567 K – 66K – 186 K = 315 K or 126°F.
REPORT #:

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Repeating this analysis for the scenario in which the over-temperature switch should fail, it is assumed 

that the maximum temperature that the duct could possibly see within normal operating conditions is 

equal to the ITTMAX of 775°C(1427°F). Substituting TACM with ITTMAX, results in a Q of 607 W.

ΔT2 = 606 W x 0.305 K/W = 185K

ΔT4 = 606 W x 0.864 K/W = 524K

Therefore, T6 = ITTMAX - ΔT2 - ΔT4 = 1048 K – 185K – 524 K = 339 K or 151°F.
REPORT #:

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APPENDIX C

Fault Tree Diagram for Auxiliary Fuel Tank