Enclosure

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Petition for Exemption from Title 14 CFR 25.961(a)(5) Amendment [25-57], Fuel System Hot Weather Operation

Name and Address of the Petitioner
Douglas M. Lane, Director The Boeing Company

PO Box 3707 Seattle, Washington, 98124

Section(s) of the Regulations from which Relief is sought: §25.961(a)(5) Fuel System Hot Weather Operation: "(a) The fuel system must perform satisfactorily in hot weather operation. This must be shown by showing that the fuel system from the tank outlets to each engine is pressurized, under all intended operations, so as to prevent vapor form ation, or must be shown by climbing from the altitude of the airport elected by the applican t to the maximum altitude established as an operating limitation under Sec. 25.1 527. If a climb test is elected, there may be no evidence of vapor lock or other malfunctioning during th e climb test conducted under the following

conditions: (5) The fuel temperature must be at least 110° F."

Extent of Relief and Reason Boeing is requesting relief from the requirement s of 14 CFR 25.961(a)(5), Amendment [25-57], for the Pratt & Whitney-powered 767-2C. The regu lation requires that the airplane and engines perform satisfactorily with the critical fuel at a temperature of at least 110°F. Boeing requests that the FAA approve a set of limitations for JP-4** and Jet B fuels on the Pratt & Whitneypowered 767-2C in lieu of compliance to the sp ecified temperature of 110°F. The limitations consist of restricting the maximum fuel temperature to 85°F, restricting the cruise altitude vs. fuel temperature, and making use of fuel tank temperature indication to allow JP-4 usage in any tankincluding the center and body tanks. Similar limitations were approved for the Rolls Roycepowered 757-300 and 747-400/-400F. This exemption from the 110 ° F requirement is required because the properties of JP-4 will not support op eration at that temperature under all intended operations.

Boeing submits this petition for the following reasons:

(1) It is in public interest. The customer for the 767- 2C requires their aircraft be able to operate

with JP-4 and Jet B fuels. A maximum temperature of 85°F will meet their operational requirements.

(2) The 767-2C will demonstrate fuel feed perf ormance under normal and abnormal conditions with JP-4 at the maximum temperat ure allowed under this exemption.

(3) The 767-2C will demonstrate fuel feed perf ormance under normal and abnormal conditions to cover all other approved fuels to temperatures in excess of 110°F.

(4) The 767-2C will be certified with an inerting system in all ta nks that will limit flammability below the levels required by 14 CFR 25.981(b).Enclosure

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(5) The proposed limitations on fuel temperatur e and maximum altitude for cruise provide a level of safety equal to that intended by 14 CFR 25.961(a)(5).

(6) The FAA has granted similar exemptions in the past:

(a) for the Rolls Royce-powered 757-300 (FAA Exemption No. 6867, issued 2/12/1999) (b) for the Pratt & Whitney-powered 757- 300 (FAA Exemption No. 7790, issued 6/3/2002) (c) for the Rolls Royce-powered 747-400/400F (FAA Exemption No. 7496, issued 4/12/2001) (d) the Rolls Royce-powered 757-200 has had an 85°F temperature limitation for JP-4 and Jet B fuels since entry into service in 1983.

**JP-4 is a military designation for a Jet B t ype commercial grade fuel with additives.

Description of Issue Boeing is introducing a 767-2C airplane model powered by Pra tt & Whitney PW4062 engines. The 767 with Pratt & Whitney PW4000 series engines was introduced in 1986, and has accumulated over 15.1 million flight hours of revenue service. Th e 767-2C will offer only the PW4062 engine at this time. The cu stomer has requested the aircraft be certified to operate with

JP-4 fuel in all tanks. The 767 with PW4000 series engines is currently cer tified to operate with JP-4 fuel, as listed on the Type Certificate Data Sheet, however, there is an Airplane Flight

Manual limitation that does not allow it for revenue flights.

With regard to 14 CFR 25.961(a)(5), the ability of an airplane to operate with JP-4 and Jet B fuels is a function of the vapor pr essure of the fuel, which increas es with temperature. The vapor pressure of wide cut fuels such as JP-4 and Je t B is considerably higher than narrow cut fuels

such as Jet A. Under normal co nditions, the aircraft fuel boost pumps maintain the pressure in the fuel feed system above th e vapor pressure of the fuel.

If all aircraft boost pumps are inoperative, the engi ne fuel pumps will continue to draw fuel out of the main tanks to maintain engine operation. This is termed suction feed operation. At high fuel temperatures and high altitudes, the pressure in the fuel feed system can decrease to, or reach a value near the vapor pre ssure of the fuel allowing some fuel to vaporize and potentially causing engine flameout. Regulation 14 CFR 25.961(a)(5) addresses this condition, among others, and is intended to insure that airplane operation will not be adversely impacted by fuel temperature. Boeing seeks to establish appropriate temperature and altitude limitations to ensure the intent of the regulation is met.

Statement of Public Interest It is in the public interest that the 767-2C be able to operate w ith JP-4 and Jet B fuels. These fuels are used in some parts of the world, partic ularly in cold weather areas due to their low freezing point. Occasionally they are the only fuels available at military or diversion airfields.

Use of JP-4 and Jet B fuels in all tanks will allow the 767-2C greater utilization and flexibility.Enclosure

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The 767-2C will provide industry-leading operating economics and environmental improvements. The 767-2C will be replacing ol der aircraft with poorer fuel economy and higher maintenance costs. Granting this petiti on will reduce operationa l costs by reducing the

amount of fuel consumed and reducing aircraft maintenance costs. The reduction in fuel consumed will also result in reduced engine em issions into the atmosphe re. These benefits will accrue with no decrease in safety.

Statement of No Adverse Effect on Safety Boeing believes that incorporating a temperatur e limitation of 85°F for JP-4 and Jet B fuels provides a level of safety equal to that inte nded by the regulation. This position is based on the following:

(1) Suction feed performance flig ht testing with JP-4 at th e maximum allowed temperature

will be demonstrated for certification.

(2) The following proposed altitude restrictions are based on fuel temperature and will be incorporated to keep fuel pressure and V/L (vapor/liquid) ratio within the engine manufacturer’s limitations at the engine pump inlet.

Fuel Tank Temperature (°F) Altitude Limit (feet)

65 to 85 32,000

45 to 65 36,000

25 to 45 39,000

25 or lower 40,100

(3) The fuel tanks must be defueled to sump level (i.e. level at which fuel pump lowpressure lights illuminate) followi ng operations with JP-4 or Jet B fuel. If the fuel tanks are not defueled, the JP-4 fuel usage limitations shall c ontinue to apply.

(4) The maximum fuel temperature of the le ft main tank, center wing tank, forward body tank, and aft middle body tank is indicated in the f light deck which allows the Flight Crew to operate within the limitation including when th e center or body tanks contain JP-4 or Jet B

fuel.

(5) The AFM (Airplane Flight Manual) will in clude ground dispatch guidelines that will enable the operator to comply with the temper ature limitation requested in this exemption.

It should be noted that there is an inherent margin of safety asso ciated with limiting JP-4 or Jet B fuel usage based on suction fuel feed capability. Under normal cond itions, the airplane fuel boost pumps will be functioning. There are two AC powered boost pumps in each of the main fuel tanks, and two AC powered override pumps in the center fuel tank. Under pressure feed conditions, the airplane can operate normally with JP-4 fuel at a temp erature of 110°F up to

maximum altitude. Suction feed operation is required only when all AC power is lost on theEnclosure

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airplane. The probability of this occurrence is ex tremely low due to redundancies incorporated in the airplane electrical system.

Request to ‘Waive Publication and Comment’ Not requested.

Privileges of the Exemption Outside the United States Not requested.

Summary to be Published in the Federal Register Boeing is requesting relief from the require ments of 14 CFR 25.961( a)(5), Amendment 57, for JP-4 and Jet B fuel usage on 767-2C progra m. The regulation require s that the airplane and engines perform satisfactorily with the critical fuel at a temperature of at least 110°F. Boeing requests that the FAA a pprove limitations for JP-4 and Jet B fuels on 767-2C in lieu of compliance to the specified temperature of 110°F. The limitati ons would consist of restricting the fuel temperature to 85°F, and altitude restrictions. The altitude restrictions will be based on fuel temperatur e to keep fuel pressure and V/L (vapor/liquid) ratio within the engine manufacturer’s limitatio ns at the engine pump inlet.

Similar exemptions have been approved on 757-300 and 747-400/-400 F model airplanes. Boeing asserts that an exemption to 14 CFR 25. 961(a)(5) subject to the limitations presented herein is in the public interest and maintains a level of safety equal to that intended by the regulation.