UNITED STATES OF AMERICA 

DEPARTMENT OF TRANSPORTATION 

FEDERAL AVIATION ADMINISTRATION 

RENTON, WASHINGTON 98057-3356 

In the matter of the petition of 

Exemption No. 12733 

The Boeing Company Regulatory Docket No. FAA-2014-0661 

for an exemption from§ 25.979(d) and (e) 

ofTitle 14, Code ofFederal Regulations 

GRANT OF EXEMPTION 

By letter dated August 19, 2014, Mr. David Hom, ODA Lead Administrator, The Boeing 

Company, 6001 S. Air Depot, Oklahoma City, Oklahoma, 73135, petitioned the Federal Aviation 

Administration (FAA) for an exemption from the requirements of§ 25.979(d) and (e) ofTitle 14, 

Code of Federal Regulations (14 CFR). This exemption, if granted, would permit the use of 

industry standard pressure loads for onload and offload fueling installations on supplemental type 

certificate (STC) modified 767-2C tanker airplanes instead of the regulatory requirement of an 

ultimate pressure of 2.0 times the limit load at maximum pressures, including surge. The 

requested exemption would apply to military use only and would ensure consistency within the 

current military fleet. 

The petitioner requests relief from the following regulations: 

Section 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 defueling pressure (positive or negative) at the airplane 

fueling connection. 
The petitioner supports its request with the following information: 

This section quotes the relevant information from the petitioner's request, with minor edits for 

clarity. The complete petition is available at the Department of Transportation's Federal Docket 

Management System, on the Internet at http://regulations.gov, in Docket No. FAA-2014-0661. 

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 pounds per square 

inch gage (PSIG). The onload and offload systems and its operations ofthe 767-2C SIC 

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, 

and Aerial Refueling Systems Advisory Group (ARSAG) specifications: 

Operating (normal/working) pressure 

Proof (limit) pressure 

Burst (ultimate) pressure 

120 PSIG 

240 PSIG (2x operating) 

360 PSIG (3x operating, 1.5x proof) 

FAA regulations in 14 CFR address civil operational use of the aircraft. These 

regulations do not envision civil aircraft being modified for in-flight onload and offload 

fueling operations (a non-civil function). In order to meet§ 25.979(d) and (e), the 767-

2C would be required to meet a burst pressure of 480 PSIG (2 x 240 PSIG). 

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

existing baseline fuel system. The certified 767-2C amended type certificate (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. 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 incorporates fuel 

system design features carried forward to the 767-2C onload and offload installations. 

The 767-2C 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 

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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) and (e) that the 767-2C onload and offload installations 

do not meet is the 2.0 times the load arising from the maximum pressures. The 

regulations are 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 United States Air Force (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) and (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 airplane 

flight manual (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 on load and 

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. 

Federal Register publication 

Although the petitioner requested that action on its petition not be delayed for publication in the 

Federal Register, the FAA found that the petition, if granted, would set a precedent. Therefore, 

to allow an opportunity for the public to comment on the petition, we published a summary of it 

in the Federal Register on July 6, 2015 (80 FR 38505). No comments were received. 

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The FAA's analysis 

Aerial refueling is not an approved operation of commercial airplanes and the requested 

exemption only applies to military refueling operations. The 767-2C airplane is not currently 

commercially available; however, we recognize that future sales or conversions could include 

airplanes that are the subject of this exemption and these airplanes could be used in commercial 

service. Boeing addresses this concern by providing operating limitations in the AFM that will 

prevent aerial refueling operations in commercial service. 

In addition, Boeing will demonstrate that the maximum surge pressure during failure conditions 

will maintain a safety factor of 1.5. This safety factor margin has been adequate on previous 

military refueling aircraft and the proposed fuel system burst pressure limits provide the 

capability proven in other military aerial refueling airplanes. Granting this exemption will not 

adversely impact public safety. It will enhance the United States military by replacing older, less 

efficient tanker airplanes and ensure consistency within the current USAF fleet. 

The FAA's decision 

In consideration of the foregoing, I find that a grant of exemption is in the public interest. 

Therefore, pursuant to the authority contained in 49 U.S.C. 40113 and 44701 delegated to me by 

the Administrator, I grant The Boeing Company an exemption from 14 CFR 25.979(d) and (e). 

The exemption is granted to the extent necessary to allow The Boeing Company to use industrystandard design pressures that have a lower factor of safety than is required by§ 25.979 on STC 

modified 767-2C military tanker airplanes. 

This exemption is subject to the following condition(s): 

1. The fuel onload and offload installations on the STC modified 767-2C must withstand an 

ultimate load that is 1.5 times the load arising from the maximum pressures, including 

surge that is likely to occur during onload and offload fueling operations. 

2. The STC modified 767-2C must add an operating limitation in the AFM that states that 

onload and offload operations are limited to military use only as allowed by FAA Order 

8110.101. This will prohibit civil in-flight onload and offload system operations. 

Michael Kaszycki 

Acting Manager, Transport Airplane Directorate 

Aircraft Certification Service 

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