FIGURE S-1 Potential fuel savings by selected large nonfighter aircraft (based on a fuel price of $2.14 per gallon). SOURCE: Committee generated.

The committee conducted a constrained cost/benefit analysis for each viable engine/airframe modification or re-engining candidate.1 The committee concluded there are a number of modification and re-engining options that deserve careful consideration and might pay for themselves within the remaining life of the engine/aircraft. Table S-1 summarizes the committee’s analysis of re-engining options. Table S-2 summarizes the committee’s analysis of engine modification options.


After the prepublication version of the report was released on January 31, 2007, errors were discovered in the input data used by the committee to estimate net present values. These errors affected the results shown in several tables and figures in Chapter 5, Appendix G, and the Summary. In addition, the committee had made these estimates for the various aircraft/engine combinations using a mix of cost estimating relationships (CERs) and market data (if the latter were available). This mixed method meant that some of the aircraft/engine cost estimates based on CERs were being compared with other estimates using both CERs and market data. In redoing these calculations using reconfirmed input data, the committee decided to base the cost estimates on CERs only since market data were not available for all engines and could in any case vary significantly over time and by source. The members of the committee with extensive industry backgrounds (engine companies) agreed that the market data should be removed from the analysis. The reasoning was straightforward: Market data are just that—they represent the opening for price negotiation and not a precise sales price to be published. The Air Force always evaluates and negotiates sales price of a proposal at best and final. Each table and figure affected by the committee’s reanalysis is identified by a footnote. While the new data did not make Air Force decisions to re-engine or upgrade more likely or less likely, nor change the recommendations offered in this report, the revised analysis is more correct, more realistic, and more useful to the Air Force as input to its decision-making process.

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