# Gulfstream

A GENERAL DYNAMICS COMPANY

August 30, 2012
A&C-12-642

U.S. Department of Transportation

Docket Operations

West Building Ground Floor, Room W12-140

1200 New Jersey Avenue, SE. Washington, DC 20590

Subject: Request for Exemption from Section 25.981 (a)(3) Fuel System Ignition

Prevention

FAA Project No.: TC8700AT-T

Attachment: Petition for Exemption

- Uncontrollable High Thrust Failure Conditions,

Model GVI

Dear Sirs:

In accordance with the provisions of 14 CFR 11.81, Gulfstream requests a time limited exemption to 14 CFR 25.981 (a)(3). This exemption, if granted, would permit relief from demonstrating that the DC powered fuel pumps meet these fuel tank ignition prevention requirements until Gulfstream is able to validate the fuel pump installat i on on the GVI. The

attached petition provides the background and rationale for why we believe granting this exemption is appropriate.

If you have any questions or require any additional information please contact me via the

contact information listed below or Natalie Mault at 912-965-5466

.

Sincerely,

# ~~ Robert Glasscock
Certification Director, G650 Program

Gulfstream Aerospace Corporation
P.O. Box 2206, MIS R-03 Savannah, GA 31402-2206

robert

. glasscock@gulfstream

. com (912) 965-6817

cc: N. Berrryman, FAA ACE-100G (via email)

P. Hatton, EASA (via email)

M. Gordon, FAA ANM-113 (via email)

P

. O. Box 2206 • Savannah, GA 31402-2206 USA. Telephone (912) 965-3000 • gulfstream.com

### Gulfstream Aerospace Corporation

ATTACHMENT to A&C-12-642 Petition for Exemption – Fuel Tank Ignition Prevention Model GVI Page 1 of 3

Relief from 14 CFR 25.981(a)(3) Amdt. 25-102

Gulfstream Aerospace Corporation (Gulfstream) of Savannah, Georgia has submitted an application to the FAA’s Atlanta Aircraft Certification Office for type certification of a new, twin-engine, transport category aircraft to be known as the Gulfstream model GVI. FAA Project Number TC8700AT-T has been assigned to this effort.

The model GVI fuel system incorporates four DC fuel boost pumps. The boost pumps are installed in the wing (2 each side), located next to each other in the fuel hopper area of the tank. The electric pumps feature a 28V brushless DC motor.

14 CFR 25.981(a)(3) as amended by Amendment 25-102 requires in part that:

(a) No ignition source may be present at each point in the fuel tank or fuel tank system where catastrophic failure could occur due to ignition of fuel or vapors. This must be shown by:

(3) Demonstrating that, an ignition source could not result from each single failure, from each single failure in combination with each latent failure condition not shown to be extremely remote, and from all combinations of failures not shown to be extremely improbable. The effects of manufacturing variability, aging, wear, corrosion, and likely damage must be considered.

In accordance with the provisions of 14 CFR 11.81, Gulfstream requests a time limited exemption to 14 CFR 25.981(a)(3). This exempt ion, if granted, would permit relief from fully demonstrating that the DC powered fuel pumps meet the fuel tank ignition prevention requirement of 14 CFR 25.981(a)(3) until Gulfstream is able to fully validate the fuel pump installation on the GVI.

Supportive Information:

Gulfstream has always intended to comply with 14 CFR 25.981. However, during a review of Gulfstream’s substantiating data for the DC fuel boost pumps, the FAA identified additional testing to demonstrate t he effectiveness of certain ignition protection features within the pumps. Some of the design aspects that must be addressed by additional substantiation include, but may not be limited to, demonstrating that the fuel pump internal wiring conduits provide an arc proof barrier that won’t be lost due to damage from any foreseeable wiring fault.

The Gulfstream GVI is nearing the conclusion of its Type Certification effort which began with initial application in September of 2005. It is impractical for Gulfstream to complete this substantiation in a timely manner. Gulfstream respectfully submits this petition for a time-limited exemption from the provisions of 14 CFR 25.981(a)(3) as they apply to the DC fuel boost pumps. Gulfstream anticipates that all additional testing deemed necessary by the FAA will be completed within 12 months from the granting of this exemption, and that full compliance of the fuel pump design will be demonstrated no later than 18 months from the granting of this exemption. In the event that a retrofit is

### Gulfstream Aerospace Corporation

ATTACHMENT to A&C-12-642 Petition for Exemption – Fuel Tank Ignition Prevention Model GVI Page 2 of 3

required, Gulfstream will begin introducing the change into production no later than 18 months from the granting of this exemption, and complete a retrofit of the entire fleet no later than 36 months from the granting of this exemption.

Gulfstream proposes that these dates are appropriate considering that:

• Gulfstream anticipates that approximately 40 to 65 aircraft will be delivered within 18 months of the granting of this exemption, and that those aircraft will be utilized less than 30,000 hours during this period. If a retrofit of those aircraft is required, Gulfstream anticipates that the time to complete that retrofit of these aircraft (i.e., an additional 18 months) would result in no more than 50,000 additional flight hours. This represents a negligible addition to the overall fleet risk;

• Some of the identified failure modes of concern require significant aircraft utilization and/or aging to potentially develop into noncompliant failure conditions, and the timeframe proposed for this exemption is not sufficient for the affected airplanes to accumulate the flight hours or cycles required for the components to exhibit these aging effects;

• The design of the pump ensures minimal opportunity for wire movement and chafing to occur, thus the potential for an arc is negligible.

• The wiring, insulation, and wire conduits are all made from industry leading materials that were specifically designed to prevent the concerns raised by the FAA.

Effect of the Exemption on Safety

While issuing an exemption implies a lower st andard of safety, Gulfstream believes that the pump as designed is more robust and better suited to preventing ignition sources than those currently installed on thousands of business jets that do not currently have to meet the requirements of 14 CFR 25.981(a)(3) at Amendment 25-102. As such, Gulfstream believes there will be no negative impact on the current level of safety. Further, the robust design of the GVI fuel boost pumps in comparison to that of business jets not meeting the standards of 14 CFR 25.981(a)(3) at Amendment 25-102 will actually result in an increase in safety. In addition, the time limited nature of this exemption will ensure that the number of airp lanes delivered is negligible to the overall
fleet risk.

Issue of Public Interest

Gulfstream Aerospace Corporation designs, develops, manufactures, markets and services the world's most technologically advanced business jet aircraft to an international market. Gulfstream’s leadership position in the global business jet market is due to the efforts of its more than nine thousand employees in the manufacturing plants, completion centers, and service centers across North America. The corporation utilizes numerous products, such as avionics and envir onmental control systems, from scores of suppliers located through out the United States. Gulfstream competes for new business all over the world. This exemption will directly impact the ability to certify the Gulfstream model GVI aircraft thereby having a direct effect on aircraft sales. Manufacture, completion, and support of Gulfstream aircraft aids in the stabilization of the job market

### Gulfstream Aerospace Corporation

ATTACHMENT to A&C-12-642 Petition for Exemption – Fuel Tank Ignition Prevention Model GVI Page 3 of 3

as well as the growth of the American economy. This is certainly in the interest of the public.

While the nature of an exemption implies a lowering of safety standards, the model GVI is an all new aircraft design which introduces to the flying public a number of advancements in safety that come with meeting the most recent regulatory requirements. Delaying the introduction of the GVI will restrict the advancement in safety introduced by this aircraft, not only in the areas of fuel system protection, but throughout the airplane. The advancement of aircraft safety is in the interest of the public.

Waiver of Notice and Public Procedure

Gulfstream respectfully requests that, and believes that good cause exists why; action on this petition should not be delayed by publication and comment procedures. Gulfstream requests that the 120-day FAA review and processing period specified in 14 CFR 11.63 (d) be reduced to support Gulfstream’s requested date of type certification. Gulfstream feels this request is appropriate because it does not set a precedent, and because the relief requested herein is identic al to exemptions granted previously. Specifically, similar relief has been granted to Embraer S.A. via Exemption Number 10180A (regulatory docket number FAA-2010-1265).

Operation Outside of the United States

Gulfstream requests consideration be given to extending this partial exemption for operation outside of the United States. Gulfstream aircraft are routinely registered and operated outside of the United States and projections are the same for the model GVI. Gulfstream believes that limiting this exempt ion to use within the U.S. would put unfair restrictions on the marketability of this aircraft.

Conclusion

Gulfstream believes that the above arguments favor a grant of time limited exemption from 14 CFR 25.981(a)(3) for the DC powered fuel boost pumps on the Gulfstream Model GVI aircraft and its derivatives. Granting this request is in the public interest and will not adversely affect current transport airplane fleet safety.