Enclosure to A&C-12-227 April 2, 2012 Page 1 of 4

Petition for Time Limited Exemption Gulfstream Aerospace Corporation Uncontrollable High Thrust Failure Conditions

Model GVI

Relief from section 14 CFR Part 25.901(c) Amdt. 25- 46

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 will incorporate Rolls-Royce Deutschland BR700-725A1- 12 series engines. These engines incorporate Fu ll Authority Digital Engine Control Systems.

14 CFR section 25.901(c), Amendments 25-1 through 25-120: Requires that “. . . no single failure or malfunction or probable combination of failures will jeopardize the safe operation of the airplane . .

.”

During the development phase of the GVI, Gulfstream intended to fully comply with the requirement. However, failure analysis of the final design highlighted a fuel metering valve jammed condition that would prevent the GVI from fully demonstrating comp liance for all flight conditions. During takeoff, the fuel metering valve could jam in the open position at higher speeds during the takeoff roll near V1. If this occurs and the crew elects to reject the takeoff, this could result is a runway excursion.

In accordance with the provisions of 14 CFR 11.81, Gulfstream requests a time limited partial exemption to 14 CFR 25.901(c). This partial exemption would be for the extremely remote powerplant failure condition identified above that could adversely affect safe operation in a very limited portion of the flight envelope of the GVI aircraft, and its derivatives, that incorporate Rolls-Royce Deutschland BR700-725A1-12 series engines. Granting this exemption would permit type certification of the Gulfstream GVI airplane and future modifications/derivatives.

This partial exemption, if granted, will require Gulf stream to demonstrate that the overall level of safety of the engine control system of the Model GVI, including future derivatives, will not be less than that of the current transport category aircraft fleet.

The exemption is requested to be granted for a period of 4 years after FAA issuance. During this period, Gulfstream will develop and make available im proved Uncontrollable High Thrust (UHT) logic. The improved logic will mitigate the effects of an UHT event during takeoff. Prior to expiration of the exemption, the engine control system modification w ill be certified as a design change, introduced into production, and all delivered airplanes will be retrofitted.

The nature of this petition for partial exemption is si milar to previously granted exemptions for Airbus

models A340 and A318, Embraer models EMB-135B J, EMB-145XR, ERJ 170, and ERJ 190, Boeing

models 757 and 777, Dassault-Aviation Falcon 7X, and the Gulfstream models GIV-X, GV-SP and

G280.Enclosure to A&C-12-227 April 2, 2012 Page 2 of 4

Supportive information

A committee consisting of representatives from the FAA, the JAA, airplane manufacturers, and engine manufacturers was formed in 1998 to study strategies for providing additional protection from thrust control malfunctions resulting in UHT. The committee found that for the existing in-service airplanes, the propulsion systems demonstrated a level of reliab ility on the order of one UHT event per 10 million flight hours. The committee also noted it would not be in the public interest to mandate major and novel design changes in an attempt to eliminate the already small exposure potential to UHT malfunctions resulting from single failures. The committee’s recommended approach to ensure continued high levels of reliability for all presently certified models is to monitor in-service performance and if any unacceptable failure modes are identified, take prompt corrective action by introducing focused design improvements using proven technology.

The approach of taking action to correct specific problems as they are identified has been usedsuccessfully for many years on previous Gulfstream models, some of which also incorporate RollsRoyce Deutschland BR700-series engines. The Gulfstream fleet has maintained a high level of safety and reliability.

Gulfstream will implement a change designed specifica lly to accommodate the failure as previously described. Full compliance with 14 CFR 25.901(c) will require Gulfstream to implement changes to the existing Electronic Engine Control (EEC) softw are to initiate engine shutdown via the overspeed shut-off mechanism following detection of a fuel metering valve jam, while the aircraft is on the ground and when the affected engine throttle is retarded to idle.

Gulfstream intends to demonstrate that those combinations of failures that could jeopardize safe operation comply with 14 CFR 25.901(c) in that they are not “probable combinations 1 .” However, Gulfstream has identified that an extremely remo te single failure condition exists which could jeopardize safe operation with potentially severe effects. Compliance with 14 CFR 25.901(c) requires each identified single failure be assumed to occur under all anticipated combinations of airplane operating and environmental conditions. While the single failures must be assumed to occur regardless of their probability 2 , probability can be considered when determining what combinations of operating and environmental conditions are anticipated to occur in the fleet life of the airplane type. Single failures do not need to be assumed to occur during operating and/or environmental conditions that are not expected to occur.

1 The term “probable,” as used in § 25.901(c) has a very different meaning than the same term as subsequently used in association with § 25.1309(b) compliance. As used in §25.901(c), "probable" means “foreseeable”. In §25.1309(b) terms, this means the subject failure conditi ons are "anticipated to occur” (i.e., aren't "extremely improbable”).

2 Probability has been an acceptable means of supporting a finding that a particular "combination" of failures are not "probable". Any single failure that has an identifiable cause is typically characterized as "anticipated to occur", unless within the relevant exposure envelope t he failure can be clearly and acceptably ruled out, as is the case for those structural failures sp ecifically excepted by the rule itself.Enclosure to A&C-12-227 April 2, 2012 Page 3 of 4

Issue of Public Interest

Gulfstream designs, develops, manufactures, mark ets 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 twelve thousand employees in the manufacturing plants, completion centers, and servic e 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. Granting this exemption will support the certification of the Gulfstream Model GVI aircraft in a timely manner, thereby having a direct effect on GVI aircraft sales. Manufacture, completion, and support of Gulfstream aircraft aids in the stabilization of the job market as well as the growth of the American economy. This is certainly in the interest of the public.

Requiring the Model GVI to comply with this rule w ould prevent Gulfstream from certifying the aircraft on a timely and competitive schedule, putting it at an unfair disadvantage to its competitors, which include foreign and domestic aircraft manufacturers. During this time, sales of previously certified aircraft, which may also have an exemption to 14 CFR 25.901(c), will continue. This will delay the introduction to the public of advancements in safety brought forth by the Model GVI, not only in the areas of engine control, but throughout the airplane. This is counterproductive to both Gulfstream and the FAA’s goal of continuous improvement in ov erall aircraft safety. The advancement of aircraft safety is in the interest of the public.

Effect of the Exemption on Safety

As stated above, Gulfstream will demonstrate that the risks due to UHT failure conditions on the GVI in its current configuration will not exceed those currently known and accepted for comparable existing transport category airplanes. This means that granting a partial exemption will not adversely affect and, in fact, will improve the average per flight hour risk within the current transport airplane fleet. For this purpose, Gulfstream analyzed the Uncontrollable High Engine Thrust failure rate data of the Rolls-Royce Deutschland BR700-725A1-12 series engines and performed simulated flight assessments of the scenarios. The results of the analysis and assessments shows that the frequency of occurrence of UHT event on the GVI is calculated to be ~1.3 E-8 per airplane operating hour, which is less than the average industry value of 1.0 E-7 per airplane operating hours.

Gulfstream agrees to demonstrate that all prac ticable actions have been taken to minimize the adverse effect on safety associated with granting of the exemption from 14CFR 25.901(c) for the GVI Model aircraft. Furthermore, Gulfstream Aerospace would like to emphasize the following:

 The GVI aft fuselage mounted engine design (i.e., relative close proximity to aircraft centerline) mitigates much of the adverse yaw condition that may be generated during a single engine UHT event on other designs.

 The controllability assessment during UHT for conditions other than the exception noted below was evaluated by conservative Engineering simulations and determined to be compliant.

 It was found that the GVI Model complies with 14CFR 25.901(c) for any foreseeable UHT failure conditions, except for in a very limited scenario:Enclosure to A&C-12-227 April 2, 2012 Page 4 of 4

o RTO conditions where the malfunction occurs at higher speeds during takeoff roll near

V1.

 Enhanced FADEC software is in development and will be incorporated in the GVI aircraft.

Gulfstream has verified that the Model GVI exposures and failure rates are such that this airplane will not exceed the known average per flight-hour risks of comparable existing transport airplanes. Making this statement a consideration of this exemption request, in combination with the condition to further minimize the risk, means that granting this exem ption will not adversely affect, and in fact should improve, the average per flight hour risk within the current transport airplane fleet.

In support of this exemption and prior to customer delivery of any GVI aircraft, Gulfstream will develop and obtain FAA acceptance of the instructions for continued airworthiness. Further, the Uncontrollable High Engine Thrust failures shall be considered reportable to the FAA under 14 CFR Part 21.3 for any airplane certificated under this exemption.

Waiver of Notice and Public Procedure

Gulfstream respectfully requests that action on this petition should not be delayed by publication of a summary of our petition and associated comment period. We believe that the nature of this exemption does not set a precedent, the relief requested herein is effectively identical to exemptions previously granted, and delay of granting this exemption will unnec essarily delay final certification of the Model

GVI.

Operation Outside of the United States

Gulfstream requests consideration be given to ex tending this 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. Gulf stream 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 time-limited, partial exemption from 14 CFR 25.901(c) for the aft-fuselage-mounted installation of the Rolls-Royce Deutschland BR700-725A1-12, FADEC-controlled engines on the Gulfstream Model GVI aircraft and its derivatives. Gulfstream believes that an exemption is in the public interest and will not adversely affect the current transport airplane fleet safety.