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 installation 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 exemption, 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 the 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 standard 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 airplanes 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 environmental 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 identical 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 exemption 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.