KC-135R/T undergoing programmed depot maintenance at contractor facilities, the Air Force should consider adding wingtip modifications to the existing overhaul contract.

Other Aircraft

The next priority aircraft for consideration of wingtip modifications are the C-5 and the C-17. The same factors discussed in the investment strategies for the KC-10 and the KC-135R/T should be part of the planning process for these fleets as well.

Financing Mechanisms

Wingtip modification programs and other fuel economy investments are examples of long-term investments that may require a significant initial investment that provides returns over time. Securing financing for such long-term investments is always a challenge given the current military acquisition practices and congressional appropriation processes. In a previous report on engine fuel economy in military aircraft,4 the NRC discussed innovative financing mechanisms that might be pursued. The statement of task for that study included a request to “develop implementation strategies to include conventional as well as innovative, acquisition, financing, and support concepts.” The committee believes that three of the mechanisms discussed in that report—specifically, creating a line item in the defense budget, implementing an “energy savings performance contract” strategy, and competing airframe maintenance contracts—could be applicable in implementing wingtip modifications. Those mechanisms are discussed in some detail in the earlier report.


NRC, 2007, Improving the Efficiency of Engines for Large Nonfighter Aircraft, Washington, D.C.: The National Academies Press.

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