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U.S. Department of Transport Field Aviation Company Inc.

Docket Operations 2450 Derry Road East

West Building Ground Floor Mississauga, Ontario

Room W12-140 Canada L5S 1B2

1200 New Jersey Avenue, SE

Washington, DC 20590

United States of America

Subject, Petition for Exemption to FAR 25.981 (a)(3) Amendment 25-125 of 

Title 14, Code of Federal Regulations.

Dear Certification Official

Exemption Specifics and Extent of Relief

Field Aviation, in this case the petitioner, wishes to apply for an exemption 

to FAR 25.981(a)(3) at Amendment 25-125 (Fuel Tank Explosion Prevention).

Reason for Relief

We have applied for a U.S. STC via the Canada U.S. Bi-lateral Airworthiness 

Agreement, U.S.Project ref. ST7041NY-T, to enable the installations of 

auxiliary fuel tank systems applicable to the Bombardier DHC-8-100, 200 and 

300 legacy series of aircraft.

We are unable to fully comply with the requirements set forth within section (a) 

(3) and stipulate from our perspective that further means of compliance is

impractical due to the fact that our auxiliary fuel tank installation is an aftermarket 

design that is incorporated within existing OEM aircraft wing structure.

Public Benefit

Public benefit is shown by the extent our design is compliant with the regulation.

With respect to Fuel Tank Lightning, HIRF Protection and Component Failures,

Field Aviation has incorporated within our installation design, to the maximum 

extent practical, three levels of highly reliable, independent and redundant 

protective features to prevent sources of ignition.

Field Aviation Company Inc.

2450 Derry Road East,

Hangar 2

Mississauga, Ontario,

Canada L5S 1B2

Phone: + 1 905 676 1540

Fax: +1 905 676 0977

www.fieldav.com
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In addition, Field Aviation has incorporated within our Instructions for Continued 

Airworthiness routine interval inspection criteria to support the continued 

functionality of protective features.

Exemption - Effect on Safety

Field Aviation’s position is that the issuance of the exemption will result in no

negative effect on safety. This is due to the quality of tank design and installation 

with respect to safety mitigation. Environmental exposure and failure protection 

measures coupled with routine interval inspection requirements facilitate, in our 

opinion, a level of equivalent safety. The Auxiliary Fuel Tanks are “substantiated 

to be conventional unheated aluminum wing tanks”. per AC25.981-1C

Additional Information

Field Aviation’s proprietary compliance report (25370105) is included with this 

petition for exemption. Contained within the report are the following elements;

Statements of Compliance – FAR 25.981 Amendment 25-125

Heat Transfer Analysis

Safety Assessment of Auxiliary Fuel System

Fault Tree Diagram

Summary

Exemption Applicability

Field Aviation is specifically seeking relief from FAR 25.981(a)(3) at 

Amendment 25-125 as it applies to the Bombardier 100/200/300 series 

aircraft.

Description of Exemption

Full compliance with the requirements set forth within section (a) (3) is 

not feasible, and we stipulate from our perspective that further means of 

compliance is also impractical due to the fact that our auxiliary fuel tank 

installation is an aftermarket design that is incorporated within existing 

OEM aircraft wing structure.
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Contact Information

Wayne T. Sprigg

Director of DAO and Flight Test

Field Aviation Company Inc.

Telephone

905-676-1540 Ext 264

Should clarification with respect to the contents of this petition be required please 

contact the undersigned directly.

Sincerely

Wayne T. Sprigg 

Doc FAA Exemption Petition – 25.981 (a)(3)