ctJ.-ao.EIND 

Y 1-0300-AC-14-230 

August 19,2014 

Docket Management Facility 

U.S. Department of Transportation 

1200 New Jersey Avenue, S.E. 

West Building Ground Floor 

Room Wl2-140 

Washington. DC 20590 

Boe1nq Compary 

6001 S PiJrOepot 

OH2horna Ctty, OK 7J 135 

.) 

Subject: Petition for Exemption from Title 14 Code of Federal Regulations (CFR) 

§25.979(d)(e) in Support of FAA Project ST00279MC· T (ODA Project 192) 

·- ·····. 

The Boeing Company respectfully submits the enclosed Petition for Exemption from Title 14 Code of 

Fedeml Regulations (CFR) §25.979(d)(e) Arndt. 25-72 from the Certification Basis for FAA Project 

ST00279MC-T (ODA Projectl92). 

The enclosure provides the details of the petition in accordance with 14 CFR § 11.81. 

DESCRIPTION OF RELIEF SOUGHT: The baseline 767-2C will be modified by the STC to be an 

in-flight tanker and receiver. The onload and offload installations could experience surge pressures 

that approach 240 pounds per square inch gage (PSIG). The baseline767-2C is designed to the 

maximum burst pressure is 360 PSIG. Higher surge pressures will occur during onload and offload. 

The STC modified 767-2C aircraft wiJJ not meet the regulatory requirement of2.0 times the ultimate 

load at maximum pressures, including surge. The petitioner requests the use of industry standard 

pressures for on load and offload installations of the STC modified 767 -2C which ensures consistency 

within the current military fleet. 

As stated in 14 CFR § 11.87, the petitioner requests that this Petition for Exemption not be delayed by 

the public process, which includes publication of the subject petition. If this exemption is not granted, 

it could lead to delays in the delivery of the 767-2C to the USAF at a critical time of need. The STC 

modified 767~2C approved aircraft will not be eligible to receive a civil airworthiness approval or 

standard certificate of airworthiness. It is intended that the aircraft will be maintained as a public use 

aircraft only for the life of the product. 

Granting of this exemption petition is kindly requested by December 15,2014. 

If you have any questions, please do not hesitate to contact the undersigned. 

Sincerely, 

~~J2.A:z( Timothy P. Wehman 

ODA -50 1296-CE Certification Engineer ODA-50 1296-CE Administrator 

Phone: 405-582-8908 Phone: 425-266-4539 

Mail Code: R7-53 Mail Code: R7-53 

Enclosure: Petition for Exemption from Title 14 Code of Federal Regulations 

§25.979(d)(e) Arndt. 25-72 

cc: Joel Ligon (FAA Wichita MCO Program Manager) 

James Hartley (FAA Wichita ACO OMT Lead) 

Jeff Duven (FAA Transport Airplane Directorate Manager) 
Enclosure to Yl:D300-AC-14-230 

Page 1 of5 

Petition for Exemption from Title 14 Code of Federal Regulations§ 25.979(d)(e) Arndt 25-72 

Name and Address of the Petitioner 

David Hom, ODA Lead Administrator 

The Boeing Company 

6001 S. Air Depot, MIS R7-53 

Oklahoma City, OK 73135 

Section(s) of the Regulations from which Relief is sought: 

§ 25.979 Pressure fueling system. 

For pressure fueling systems, the following apply: 

(d) The airplane pressure fueling system (not including fuel tanks and fuel tank vents) must 

withstand an ultimate load that is 2.0 times the load arising from the maximum pressures, 

including surge that is likely to occur during fueling. The maximum surge pressure must be 

established with any combination of tank valves being either intentionally or inadvertently 

closed. 

(e) The airplane defueling system (not including fuel tanks and fuel tank vents) must 

withstand an ultimate load that is 2.0 times the load arising from the maximum permissible 

de fueling pressure (positive or negative) at the airplane fueling connection. 

The Extent of Relief Sought and Reason(s) 

Regulation Requires: Relief is Necessary because: 

14 CFR § 25.979 (d) " ... withstand an ultimate load The baseline 767-2C will be modified by the 

Amendment 25-72 that is 2.0 times the load STC to be an in-flight tanker and receiver. 

arising from the maximum The on load installation will exceed the 

pressures, including surge, that maximum certified surge pressure of 180 

is likely to occur during pounds per square inch gage (PSIG). The on 

fueling." load installation could experience surge 

pressures that approach 240 (PSIG). The 

aircraft will not meet the regulatory 

requirement of ultimate load of 2.0 times the 

maximum pressures, including surge. 

14 CFR § 25.979 (e) " ... withstand an ultimate load The baseline 767-2C will be modified by the 

Amendment 25-72 that is 2.0 times the load STC to be an in-flight tanker and receiver. 

arising from the maximum The off load installations will exceed the 

permissible defueling pressure maximum certified surge pressure of 180 

(positive or negative) at the pounds per square inch gage (PSIG). The off 

airplane fueling connection." load installations could experience surge 

pressures that approach 240 (PSIG). The 

aircraft will not meet the regulatory 

requirement of ultimate load of 2.0 times the 

maximum pressures, including surge. 
Enclosure to Yl-D300-AC-14-230 

Page 2 of 5 

Petition for Exemption from Title 14 Code of Federal Regulations§ 25.979(d)(e) Arndt 25-72 

Description of Issue 

767-2C Baseline 

The Amended Type Certificated (ATC) 767-2C airplane is designed for the ground refueling 

operating pressures of: 

OperatingProofBurst120 PSIG 

240 PSIG (2x Operating) 

360 PSIG (3x Operating, 1.5x Proof) 

The ATC 767-2C airplane will be certified for the ground refueling operating pressures of: 

OperatingProofBurst90 PSIG 

180 PSIG (2x Operating) 

360 PSIG (2x Proof, 4x Operating) 

See Table 1 for a summary of the 767-2C design pressures. 

STC Modified 767-2C 

The baseline 767-2C certified pressures are sufficient for ground refueling and defueling of aircraft 

in the commercial environment. During onload and offload operations, receiver top offs generate 

high surges in the receiving aircraft that are reflected back in to the tanker. These surge pressures on 

other legacy refueling systems (KC-135, KC-10, and the 767 Global Tanker Transport Aircraft 

(GTTA) can approach 240 PSIG. The onload and offload systems and its operations of the 767-2C 

STC are similar to the aforementioned legacy tanker airplanes. 

The current fleet of Air Force tankers and large body receivers are built to the following industry 

standards for fuel pressure consistent with the Joint Service Specification Guide (JSSG), Joint 

Service Board (JSB), Standardization Agreements (STANAGs), Mil-Specs, Aerial Refueling 

Systems Advisory Group (ARSAG) specifications, summarily: 

Operating pressureProof pressureBurst pressure120 PSIG 

240 PSIG (2x Operating) 

360 PSIG (3x Operating, 1.5x Proof) 

See Table 1 for a summary of the 767-2C design pressures. 
Enclosure to Yl-D300-AC-14-230 

Page 3 of 5 

Petition for Exemption from Title 14 Code of Federal Regulations§ 25.979(d)(e) Arndt 25-72 

Commercial Standard Military Operation KC-46 and Operations On load Des1gn 767-200 767-2C 767-2C Offload Pressures Design ATC&STC Industry STC Installation 

Critena Ground Standard Onload Factors 

Refueling Offload 

Operating 120PSIG 90PSIG 1X 120PSIG 1X {working) 

Proof 240PSIG 180PSIG 2X 240PSIG 2X {limit) 

surges s 240 s 180 PSIG =>240 lAW s2X S2X {sproof) PSIG 25.979(d) PSIG 

Burst 360PSIG 360PSIG 3X 360PSIG 3X {ultimate) 

Notte 360PSIG 360PSIG 360PS/G 360PSIG 360PSIG Exceed 

Operating (Working) Pressure [IJ 

A maximum steady state pressure (no-flow and flowing conditions) that the fuel system can continually sustain 

throughout the life of the airframe without any external leakage, fatigue, failures or malfunction. 

Proof (limit) Pressure [IJ 

A pressure in which the fuel system may function satisfactorily including pressure transients (surges) up to a 

value in which the aircraft can continually sustain throughout the life of the aircraft without any external leakage, failure 

and/or malfunction, or deformation. Proof pressures are typically two times greater than operating pressures. 

Burst (Ultimate) Pressure [IJ 

A pressure that the fuel system can sustain without external leakage and/or rupture but may not function 

properly. Deformation without leakage is permitted. Burst pressures are typically 1.5 times greater than proof/limit 

pressures. 

Surge Pressure Limits & Interpretations [IJ 

Pressure transients occur as a result of an interruption of fuel flow, a perturbation of fuel flow or an abrupt 

change in flow velocity. Pressure transients shall not exceed proof (limit) pressure in the aircraft. 

[IJ ARSAG Document No. 00-03-01, Sections 3.4, 3.5, 3.6, 3.7, Aerial Refueling Pressures Definitions and Terms, 

Design and Verification Guidance Dec 2010 

Table 1 

FAA regulations in 14 CFR address civil operational use of the aircraft These regulations do not 

envision civil aircraft being modified for onload and offload operations (a non civil function). In 

order to meet the 14CFR 25.979(d) and (e) the 767-2C would be required to meet a burst pressure of 

480 PSIG (2 X 240PSIG). 

The 767-2C fuel system as modified by the STC will add additional functionality to the existing 

baseline fuel system. The certified 767 -2C ATC fuel systems are designed for a max burst pressure 

of 360 PSIG. 

Increasing the burst pressure to 480 PSIG to the baseline 767-2C fuel system would require redesign, 

requalification and recertification at the system level. 
Enclosure to Yl-0300-AC-14-230 

Page 4 of5 

Petition for Exemption from Title 14 Code of Federal Regulations § 25.979( d)( e) Arndt 25-72 

Additional component level requalification and recertification will be required to pump shutoff 

valves, check valves, nozzle, reception couplings, receptacles, plumbing, hose, interconnects, etc. 

It is impractical and not economically viable to make the design changes to increase the burst 

pressure to 480 PSIG. 

Historical operation of tankers (KC-135, KC-10 and GTTA) and large body receiver aircraft (C-5, 

C-17, E-3, B-52 and B-1) indicate no event of fuel system leaks with surge pressures that may 

approach 240 PSIG. This stellar operational record incorporate fuel system design features carried 

forward to the 767-2C onload and offload installations. 

The 7 67 -2C onload and offload installations have the ability of withstanding 240 PSIG surges and 

240 PSIG in a steady state condition indefinitely. Testing will be done simulating normal operations 

and single failures that generate high surge pressures to verify that all surges experienced on the 767-

2C during onload and offload operations remain below 240 PSIG. 

Statement of Public Interest 

The single aspect of§ 25.979(d)(e) that the 767-2C onload and offload installations do not meet is 

the 2 times the load arising from the maximum pressures. This regulation is specifically written for 

ground refueling operations and not onload and offload installations. Maintaining the industry 

standards for onload and offload installations utilized on programs such as the KC-135, KC-10 and 

the GTTA will provide for the most economical option for the STC modified 767-2C and provide 

consistency within the industry for onload and offload installations. 

Both the baseline 767-2C and the STC modified 767-2C maintain a 360 PSIG Burst pressure 

maximum. Any change to the 767-2C baseline fuel system would cause significant modification to 

the airplane that would provide no net benefit in the configuration and no commensurate increase in 

safety. If the relief is not granted, it could lead to delays in the delivery of the 767-2C to the USAF at 

a critical time of need. It remains in the public's interest to agree with the Boeing Company decision 

to utilize industry standards for onload and offload operating pressures which ensure consistency 

within the current military fleet. 

Statement of No Adverse Effect on Safety 

The ground refueling installations on the 767-2C will be certified in accordance with§ 25.979(d)(e). 

The STC modified 767-2C onload and offload refueling installations will meet industry standards for 

fuel pressure. Both elements of the operations shall assure that the aircraft will not exceed the 

maximum burst pressure of 360 PSIG and to operate safely within the design standards. 

The 767-2C must be operationally compatible with other tanker airplanes for onload and offload 

with current receivers and tankers which operate with surge pressures up to 240 PSIG. Along with 

meeting industry standards for onload and offload refueling installations, the STC modified 767-2C 

will add an operating limitation in the AFM that states that onload and offload operations are limited 

to military use only as allowed by Order 8110.101. This will prohibit civil in-flight onload and 
Enclosure to Yl-D300-AC-14-230 

Page 5 of5 

Petition for Exemption from Title 14 Code of Federal Regulations§ 25.979(d)(e) Arndt 25-72 

offload system operations. Additionally, due to the aforementioned limitation and other limitations 

as a result of the STC alterations, the aircraft will not be permitted to carry commercial passengers. 

Request to Waive Publication and Comment 

As stated in 14 CFR § 11.87, the petitioner requests that this Petition for Exemption not be delayed 

by the public process, which includes publication of the subject petition. If this exemption is not 

granted, it could lead to delays in the delivery of the 767-2C to the USAF at a critical time of need. 

The STC modified 767-2C approved aircraft will not be eligible to receive a civil airworthiness 

approval or standard certificate of airworthiness. It is intended that the aircraft will be maintained as 

a public use aircraft only for the life of the product. 

Privileges of the Exemption Outside the United States 

Not requested 

Conclusion 

Since §25.979(d)(e) considers ground refueling operations only, the STC modified767-2C aircraft 

will remain compliant to §25.979(d)(e) for ground refueling operations. It is requested that the FAA 

grant an exemption to Boeing allowing the use of industry standard pressures for the onload and 

offload installations on the STC modified767-2C. The STC modified 767-2C will add an operating 

limitation in the AFM that states that onload and offload operations are limited to military use only 

as allowed by Order 8110.101. This will prohibit civil in flight onload and offload system 

operations. Boeing is requesting this exemption which adequately and appropriately addresses this 

special purpose of 7 67-2C airplane. 

Summary to be Published in the Federal Register 

PETITIONER: The Boeing Company 

SECTION OF 14 CFR AFFECTED: 14 CFR §25.979(d)(e) 

DESCRIPTION OF RELIEF SOUGHT: The baseline 767-2C will be modified by the STC to be an 

in-flight tanker and receiver. The onload and offload installations could experience surge pressures 

that approach 240 pounds per square inch gage (PSIG). The baseline767-2C is designed to the 

maximum burst pressure is 360 PSIG. Higher surge pressures will occur during onload and offload. 

The STC modified 767-2C aircraft will not meet the regulatory requirement of 2.0 times the ultimate 

load at maximum pressures, including surge. The petitioner requests the use of industry standard 

pressures for onload and offload installations of the STC modified 767-2C which ensures 

consistency within the current military fleet.