Y1-D300-AC-14-357 February 12, 2015 DocketManagementFacility U.S. Department ofTransportation 1200 New Jersey Avenue, S.E. West Building Ground Floor RoomW12-140 Washington, DC 20590 The Boeing Company 6001 S. Air Depot Oklahoma City, OK 73135

Subject: Petitionfor Exemptionfrom Title 14 CodeofFederal Regulations (CFR) §25.345(c) in SupportofFAA ProjectST00279MC-T (ODA Project 192) for theModel767-2C The BoeingCompany respectfully submits the enclosed Petition for Exemption from Title 14 CodeofFederal Regulations (CFR) §25.345(c) Arndt. 25-91 from the Certification Basis for FAA ProjectST00279MC-T (ODA Project 192) for the Model 767-2C. Theenclosure provides the details ofthe petition in accordance with 14 CFR §11.81. DESCRIPTION OFRELIEF SOUGHT: USAFrequires that the KC-46A be capable ofrefueling all aircraft that may currently be refueled using KC-135 and/or KC-10A tankers. Some ofthese receiveraircraftrefuel atlow speeds that would require prolonged flight with high lift devices deployed during aerial refueling operations. Application of 14 CFR §25.345(c) would drive increased maneuver and gustloads resulting in impractical redesign ofthe wing structure. The airplane design provides adequate structural capability for aerial refueling operations with high lift devices deployed due to the limited maneuvering and the low frequency ofoccurrence. Thepetitionerrequests an exemption from 14 CFR §25.345(c). As stated in 14 CFR §11.87, the petitionerrequests that this Petition for Exemption notbe delayed by the public process, which includes publication ofthe subject petition. Ifthis exemption is not granted, itcould lead to delays in the delivery ofthe STCmodified 767-2C to the USAFat a critical time ofneed. The STC modified 767-2C approved aircraft will not be eligibleto receive a civil airworthiness approval or standard certificateof airworthiness. Itis intended that the aircraft will be maintained as a public use aircraft only for the life ofthe product. Granting ofthis exemptionpetition is kindly requested by July 15, 2015. Ifyou have any questions, please do not hesitate to contactthe undersigned. Sincerely, 

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# .;,('QIV JR Brownell ODA-501296-CECertificationEngineer ODA-501296-CEAdministrator Phone: 405-582-8908 Phone: 425-266-4539 Mail Code: R7-53 Mail Code: R7-53 Enclosure: Petition for Exemption from Title 14 Code ofFederal Regulations · §25.345(c) Arndt. 25-91
cc: Joel Ligon (FAAWichitaMCOProgramManager) James Hartley (FAAWichita ACO OMTLead) JeffDuven (FAATransportAirplane Directorate Manager)Enclosure to Yl-D300-AC-14-357 Page I of6 

### Petition for Exemption from Title 14 Code ofFederal Regulations§ 25.345(c) Arndt 25-91
Name and Address ofthe Petitioner David Horn, ODA Lead Administrator The BoeingCompany 6001 S. Air Depot, M/S R7-53 OklahomaCity, OK 73135 

### Section(s) ofthe Regulations from which Reliefis sought: 14 CFR §25.345(c) High lift devices (c) Ifflaps orotherhigh lift devices areto be used in en route conditions, and with flaps in the appropriate position at speeds up the flap design speed chosen for these conditions, the airplane is assumed to be subjectedto symmetrical maneuvers and gusts within the range determined by-- (1) Maneuveringto a positive limit load factor as prescribed in Sec. 25.337(b); and (2) The discrete vertical gust criteria in Sec. 25.341(a). 

### The ExtentofReliefSou ht and Reason(s) Regulation Requires: Reliefis Necessary because: 14 CFR §25.345 (c) Flap usage in en route conditions Applyingthis requirementto the use ofhigh Amendment 25-91 must be considered at the positive lift devices duringaerial refuelingoperations maneuvering requirements of 14 would drive increased maneuverand gust CFR 25.337(b) and symmetric loads resulting 

### in impractical redesign ofthe gust requirements of 14 CFR wing and leading and trailingedge structures. 25.34l(a). 

### Description ofIssue USAF requires that the KC-46A be capable ofrefueling all aircraft that may currently be refueled using KC135 and/or KC-IOA tankers. Some ofthesereceiver aircraft refuel at low speedsthat would require prolonged flight with high lift devices deployed during aerial refueling operations. The intent ofthe requirement of 14 CFR §25.345(c) may be satisfied by consideration ofthe expected usage ofthe KC-46A airplane, operational procedures, and inherent structural capability. Note that the KC-lOA requires a similar low speed refueling envelope with flaps down operation. The current en route flaps requirements of 14 CFR §25.345(c) were not part ofthe KC-IOA certification basis. Expected Usage Low speed refueling should be regarded as a customerrequired capability and not as common usage as envisioned by the regulation. This capability is expected to be utilized very infrequently as these flaps down refueling events are not part ofthe KC-X specification mission profiles which form the basis for structural durability evaluation. For any KC-46A, the frequency oflow altitude refuelingmissions, including flaps down refueling, is expected to be less than I0 hours/year, equivalentto I

# o-2 per flight hour.Enclosure to Yl-0300-AC-14-357 Page 2 of6 

### Petition for Exemption from Title 14 Code ofFederal Regulations§ 25.345(c) Arndt 25-91 Flaps down refueling operations are low speed, in the range of 185 to 200 KIAS and below the flaps down maximum altitude limit of20,000 ft. Flaps will notbe deployed during high speed or high altitude flight. Only takeoffflap settings, detents 1, 5, 15, and 20, may be used. Since flaps 1and 5 are sufficientto perform these missions, flaps 15 and 20 usage is expected to be rare. This operation is expected to be very infrequent. Therefore, the cumulative lifetime refueling flaps down operation is not significantboth from an exposure to elevated maneuver and gust environment and effects on the overall structural durability. Operational Procedures For aerial refueling operations, turbulence is avoided and the fuel offload maneuvering limit is 1.5g's. Similar to the KC-1OA aerial refueling operations manual, AFI 11-2KC-l0 V3, the KC-46A operations manual will instructthe flight crewto terminate refueling ifmoderate turbulence is encountered. Situational awareness is high due to proximity ofreceiver aircraft. When not in preparation or execution of slow receiver offload, the tanker aircraft would operate flaps up to minimize fuel burn during loiter segments. When not oftloading, flaps down maneuver limits remain at the current AFM limit, Og to 2g. Structural Capability As discussed in the Amendment25-46 publication preamble, the current requirement for consideration ofen route flaps is intended to address situations where the airplanes are "commonly flown in en route conditions with flaps deployed for purposes otherthan as speed brakes, and the airplane structure should be designed for the appropriate loads regardless ofthe operational reason". Sufficient and appropriate structural capability for the expected flaps down refueling operations is provided by the existing design both for offload operations and for loading conditionsfollowing disconnect. In the event that severe turbulence is encountered during aerial refueling operations, the KC-46A structural capability is sufficientfor the effects ofthe gust and rapid refueling termination and disconnect. Rapid disconnects and resulting fuel pressure transients are addressed in the basic USAF approved aerial refueling criteria. In the event ofa rapid disconnect followed by high maneuvering or severe gusts, the aircraft loads are limited by airplane lift capability to the existing structural capability as described below. During operation in the low speed refueling regime, the vertical maneuvering and gust loads are naturally limited by airplane maximum lift capability to envelopes comparable to the flaps down envelope required by 14 CFR §25.345(a). Encounters with severe head on gusts, while not required by 14 CFR 25.345(c), are also very unlikely to exceed structural capability duringthese operations. Since flaps 1and 5 are expectedto be used most often, the maneuvering and gust capabilities are shown for flaps 5, the most critical. Flaps 15 and 20 are available, but refueling operations with these settings is expected to be rare and are not considered.Enclosure toY1-0300-AC-14-357 Page 3 of6 

### Petition for Exemption from Title 14 Code ofFederal Regulations§ 25.345(c) Arndt 25-91 Figure 1shows the maximum lift limited maneuveringcapability on a speed-load factor plot at maximum gross weight for flaps 5 operation. This figure illustrates that the positive maneuvering and vertical gust loads would not be severe and also illustrates that high weight operations are not practical because ofreduced maneuvering margins to stick shaker. For flaps 1, the maximum lift capability is even lower and the same conclusions



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Figure 1- Maneuver and Gust Capability at415,000 Lbs.- Maximum Weight Case Figure 2 shows the same envelope at a more likely weight for this mission. Once again, the maneuver and gust capability is adequately covered bytheflaps down maneuvering capabilities. The structural capability is quite adequate for performing these low speed refuelingmissions. For operations at lower weights, exceedance ofthe flaps down maneuver envelope would not exceed stmctural capability.Enclosure to Yl-D300-AC-14-357 Page 4 of6 

### Petition for Exemption from Title 14 Code ofFederal Regulations§25.345(c) Arndt 25-91

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### Figure 2- Maneuver and Gust Capability at 350,000 Lbs.- Expected Typical Heavy Operations Case
A head on gust resulting in an overspeed offlap capability would be extremely improbable. Forthe worst case scenario, 200 knot refueling condition at flaps 5, a head on gust intensity of 1 I 6 feet persecond, EAS, would be needed to exceed the VF+I5 speed, 269 KEAS, for the 14 CFR §25.345(b) head on gust design condition. Gust levels ofthese magnitudes are extremely rare events in normal level flight. For comparison, the 10,000 ft. altitude design vertical gust per 14 CFR §25.341 is about 50 feet per second, EAS. Forflaps 1, 

### the gust margin is even larger, 137 feet per second, EAS. This further illustrates the adequacy oftheexisting structural design. Statement

### ofPublic Interest USAF requires that the KC-46A be capable ofrefueling all aircraft that may currently be refueled using KC135 and/or KC-1

### OA tankers. Some ofthese receiver aircraft refuel at low speeds that would require prolonged flight with high lift 

### devices deployed during aerial refueling operations. Application of 14 CFR §25.345(c) would cause significant modification to the airplane that would provide no net benefit in the configuration and no commensurate increase in safety. Ifthe reliefis not granted, it could lead to delays in the delivery oftheEnc.losure to YI-D300-AC-14-357 Page 5of6 

### Petition for Exemption from Title 14 Code ofFederal Regulations§ 25.345(c) Arndt 25-91 STC modified767-2C to the USAF at a critical time ofneed. Itremains in the public's interestto grant Boeing an exemptionto 14 CFR §25.345(c) for the STC modified 767-2C airplane. 

### Statement ofNo Adverse Effect on Safety The basic flaps down design capability provides adequate structural capability for flaps down refueling operations consistentwith the intent ofthe rule. Application ofthe specific 14 CFR §25.345(c) en route requirements is not appropriate as the low speed capability requirement does not represent typical tanker usage and the operational procedures will ensure that the KC-46A airplane is operated in a mannerto avoid structural overload. Since these low speed aerial refueling operations are expectedto be infrequent and well below the common usage intended per 14 CFR §25.345(c) en route requirements, these operations are not equivalentto the en route flaps usage as envisioned by the pertinent regulations. An exemption is requested based upon the appropriate compensatingfactors considering the expected usage ofthe airplane, basic structural capability, and operational procedures. 

### Request to Waive Publication and Comment As allowed in 14 CFR §11.87, the petitionerrequests that this Petition for Exemption not be delayed by the public process, which includes publication ofthe subjectpetition. Ifthis exemption is not granted, it could lead to delays in the delivery ofthe STC modified 767-2Ctothe USAF at a critical time ofneed. The STC modified 767-2C approved aircraft will not be eligible to receive a civil airworthiness approval or standard certificate ofairworthiness. Itis intended thatthe aircraft will be maintained as a public use aircraft only for the life ofthe product. 

### Privileges ofthe Exemption Outside the United States Not requested 

### Conclusion The Boeing position is that for aerial refueling operations involving flaps down usage, the expected usage, operational procedures and structural capability providesjustification for an exemption to 14 CFR §25.345(c) based on the limited maneuvering and the low frequency ofoccurrence offlaps down refueling operations. Boeing herby requests FAA issuance ofan exemption for 14 CFR §25.345(c) Arndt 25-91, based on the rationale presented above, for the FAA ProjectNo. STC00279MC-T- Model 767-2C. 

### Summary to bePublished in the Federal Register PETITIONER: The Boeing Company SECTION OF 14 CFR AFFECTED: 14 CFR §25.345(c)Enclosure to YI-D300-AC-14-357 Page 6 of6 

### Petition for Exemption from Title 14 CodeofFederal Regulations§ 25.345(c) Arndt 25-91 DESCRIPTION OF RELIEF SOUGHT: USAF requires that the KC-46A be capable ofrefueling all aircraft that may currently be refueled using KC-135 and/or KC-1 OA tankers. Some ofthese receiver aircraft refuel at low speedsthat would require prolonged flight with high lift devices deployed during aerial refueling operations. Application of 14 CFR §25.345(c) would drive increased maneuver and gust loads resulting in impractical redesign ofthe wing structure. The airplane design provides adequate structural capability for aerial refueling operations with high lift devices deployed due to the limited maneuvering and the low frequency ofoccurrence. The petitioner requests an exemption from 14 CFR §25.345(c).