Summary

THE BOTTOM LINE

The Air Force tasked the National Research Council with examining and assessing options for improving the engine efficiency of all large nonfighter aircraft in the force. Engine efficiency improvements can result in either better performance or decreased fuel consumption or some combination of the two. For purposes of this report the primary objective of modifying or re-engining Air Force aircraft with more efficient engines is to reduce fuel consumption. Attaining this objective would have two immediate major benefits: improved national security through reduced reliance on imported foreign oil, and reduced cost of supplying and operating the aircraft. However, there are a number of additional benefits and constraints to be considered. Aircraft performance improvements, reduced maintenance, improved reliability and safety, and reduced environmental impact could all be benefits. By the same token, the cost of the modifications or re-engining is a significant constraint, as is timing. While decisions should be based on economic benefit/cost analysis, they must also consider some of the benefits that cannot be easily monetized, such as performance improvements and national security. It may be the case that a greater-good argument prevails, with the decision being made on more than just economic grounds, and that the controlling variable is saving fuel—not at any cost but at a reasonable cost.

KEY FINDINGS

As a first cut, the Committee on Analysis of Air Force Engine Efficiency Improvement Options for Large Non-fighter Aircraft constructed a plot that mapped potential fuel savings for each aircraft type versus the remaining life, using data provided by the Air Force (Figure S-1). Figure S-1 shows the most favorable re-engine option in terms of improved efficiency and reduction in fuel consumption and plots the calculated fuel savings based on 2005 fuel consumption for each platform against the expected remaining life (AFOTC, 2006). A bubble’s diameter is proportional to the number of that type of platform in the overall fleet.



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Improving the Efficiency of Engines for Large Nonfighter Aircraft Summary THE BOTTOM LINE The Air Force tasked the National Research Council with examining and assessing options for improving the engine efficiency of all large nonfighter aircraft in the force. Engine efficiency improvements can result in either better performance or decreased fuel consumption or some combination of the two. For purposes of this report the primary objective of modifying or re-engining Air Force aircraft with more efficient engines is to reduce fuel consumption. Attaining this objective would have two immediate major benefits: improved national security through reduced reliance on imported foreign oil, and reduced cost of supplying and operating the aircraft. However, there are a number of additional benefits and constraints to be considered. Aircraft performance improvements, reduced maintenance, improved reliability and safety, and reduced environmental impact could all be benefits. By the same token, the cost of the modifications or re-engining is a significant constraint, as is timing. While decisions should be based on economic benefit/cost analysis, they must also consider some of the benefits that cannot be easily monetized, such as performance improvements and national security. It may be the case that a greater-good argument prevails, with the decision being made on more than just economic grounds, and that the controlling variable is saving fuel—not at any cost but at a reasonable cost. KEY FINDINGS As a first cut, the Committee on Analysis of Air Force Engine Efficiency Improvement Options for Large Non-fighter Aircraft constructed a plot that mapped potential fuel savings for each aircraft type versus the remaining life, using data provided by the Air Force (Figure S-1). Figure S-1 shows the most favorable re-engine option in terms of improved efficiency and reduction in fuel consumption and plots the calculated fuel savings based on 2005 fuel consumption for each platform against the expected remaining life (AFOTC, 2006). A bubble’s diameter is proportional to the number of that type of platform in the overall fleet.

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Improving the Efficiency of Engines for Large Nonfighter Aircraft 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. 1 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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Improving the Efficiency of Engines for Large Nonfighter Aircraft TABLE S-1 Re-engining Analysis Resultsa,b Aircraft Current Enginec Re-engine Candidates Years to Recoup Costsd,e C-130H T56 (T56) AE 2100, PW150 12.4-17.7 B-1 F101 F119/5.0 33.5->60 E-3 TF33 (JT3D) CFM56-2B-1, JT8D-219, CFM56-7B22 13.0-16.5 KC-135D/E TF33 (JT3D) CFM56-2B-1, JT8D-219, CFM-56-7B22 20.6-31.6 B-52 TF33 (JT3D) F117-PW-100 (4), CF34-10A (8), CFM56-5C2 (4) 12.6-16.1 aEntries corrected after release of the January 31, 2007, prepublication version of the report. bThe committee emphasizes that the analyses and the results presented in this table are not intended to be definitive assessments of the various options. A more extensive analysis may show shorter times to recoup costs, and such analysis should be conducted for selected options prior to any final decision by the Air Force. cMilitary designations shown. Designations in parentheses are commercial engine equivalents where they exist. dShortest time to recoup costs (in years) of any option with fuel at $2.50 per gallon and fuel inflation rates of 3, 6, and 9 percent. eDespite presentation of the analysis results as precise numbers, it is imperative that they be viewed and used as approximate estimates, each surrounded by some amount of uncertainty. TABLE S-2 Engine Modification Analysis Resultsa Aircraft Current Engine Years to Recoup Costsb,c KC-135R/T CFM56-2B-1 36.6->60 C-130H T56 12.6-17.8 B-1 F101 7.4-8.0 KC-10 CF6-50 3.8 aEntries corrected after release of the January 31, 2007, prepublication version of the report. bShortest time to recoup costs (in years) of any option with fuel at $2.50 per gallon and fuel inflation rates of 3, 6, and 9 percent. cDespite presentation of the analysis results as precise numbers, it is imperative that they be viewed and used as approximate estimates, each surrounded by some amount of uncertainty. The committee’s analysis did not indicate that the cost of re-engining the KC-135D/E could be recouped in less than 20 years.2 However, as discussed in the report, the committee recommends that the Air Force approach re-engining of the aircraft powered by the various models of the TF33 engine on a holistic basis, with the goal of removing the engine from the inventory. The committee examined environmental considerations and/or the benefits of each action. In addition, several other approaches to saving fuel were studied, including aircraft winglets, laminar flow nacelles, optimization of operations, engine build practices, information use, and engine water washing. The committee examined the potential impact of alternative fuels3 and engine science and technology programs. It also evaluated several acquisition, financing, and support options. The committee’s analysis was not a complete benefit/cost analysis since not all benefits associated with engine modifications, re-engining, and airframe modification to achieve fuel savings or reliability, 2 The committee’s analysis did not attempt to account for the residual value of engines (which, in general, could improve the case for re-engining or engine modification) after re-engined airframe retirement. If engine residual value were taken into account, the cost of re-engining the KC-135D/E could possibly be recouped in less than 20 years. 3 These fuels have not come into widespread commercial use in the United States partly because of their cost, but with rising petroleum cost and with increased production volume, some alternative fuels are beginning to look competitive, and technology is improving. The fact that Sasol in Africa, with FT fuel, and others in Canada, with tar sands, are in production is promising.

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Improving the Efficiency of Engines for Large Nonfighter Aircraft maintainability, availability, and/or performance improvements were monetized. It did not attempt to account for the residual value of engines after re-engined airframe retirement or for any national benefit from reduced dependence on imported foreign oil. No such analysis was feasible within the time constraints of this study. Such an analysis should be undertaken for selected options by the Air Force prior to any final decision. In particular, the Air Force should consider the potential for cost-saving or capability-enhancing changes to force structure that would be enabled by re-engining existing platforms. GENERAL OBSERVATIONS Some general observations apply across the entire fleet. First, the value of ensuring that everyone in the Air Force understands the importance of fuel conservation cannot be overstated. Fuel improvements or impacts must be part of every major decision. The C-130 Large Aircraft Infrared Countermeasures (LAIRCM) modification serves as an excellent example. The antenna for the module was mounted externally rather than flush to save installation time and money. Unfortunately the added drag significantly increases fuel consumption on the C-130. Second, similarities and commonalities between commercial and Air Force engines present opportunities to increase Air Force fuel efficiency. Commercial engines or derivatives (such as the CFM56, F108, CF6-50, CF6-80, and PW2040) are installed on several Air Force weapon systems (such as the C-135R/T, B-1, KC-10, C-5, and C-17). As commercial users modify their engines in anticipation of paybacks, those modifications should be evaluated for incorporation into the military fleet. The military may also benefit from much of the nonrecurring engineering work that will have already been done. Third, while Air Force aircraft are in depot maintenance with their engines removed to facilitate other maintenance, modifications or upgrades could be installed with no additional downtime or maintenance for the operational users of the weapon system. Rotatable pools of engines for exchange during the depot maintenance process could help exploit these opportunities. Fourth, other commercial practices present the Air Force with opportunities to save on fuel and operating costs. Examples include engine build policies that maximize fuel efficiency, parts replacement policies, water washes of engines, and scheduling and operating procedures optimized to save fuel. Fifth, the Air Force could resort more often to competition to save money. For example, it could competitively procure all new engines and parts from the manufacturers and determine the relative costs and benefits of maintaining engines in organic Air Force facilities or on contract and, for the latter, compete maintenance across all providers of such services. KEY RECOMMENDATIONS The committee’s key recommendations are listed below. Supporting discussion for these recommendations is provided in Chapters 1-9 of the report along with additional recommendations. The recommendation numbers here in the Summary correspond to their numbers in the body of the report. Proposed Engine Modifications and Re-engining Recommendation 3-3. The Air Force should pursue re-engining the C-130H on a priority basis, since this aircraft is one of the largest users of fuel in the Air Force inventory. The Air Force should use a competitive bid procurement process to provide the background for a decision on the C-130H models between the AE 2100 and PW150 engine options, either of which would appear to be accept-

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Improving the Efficiency of Engines for Large Nonfighter Aircraft able on a technical and performance basis, and it should review the economics of engine efficiency upgrades (engine modifications) to the older models with a shorter remaining service life. Recommendation 3-5. In general, where commercial engine/airframe counterparts exist (KC-10/DC-10, F103/CF6-50, KC-135/B-707, TF33/JT3, F-108/CFM56, etc.), Air Force engine and weapons systems planners, managers, and policy makers should closely monitor the engine’s original equipment manufacturers’ (OEMs’) and commercial operators’ activities and actions relative to re-engining and engine modification as a measure of the cost/benefit for these activities. Recommendation 3-6. Since the C-17/F117 system is the largest consumer of fuel, the Air Force should conduct an engine model derivative program (EMDP) study with Boeing and Pratt & Whitney to determine possible fuel savings, implementation costs, and a schedule that would give the best return on investment for the Air Force. TF33 Series Powered Aircraft Recommendation 4-1. The Air Force should approach re-engining of the aircraft powered by the various models of the TF33 engine on a holistic basis with the goal of removing the engine(s) from the inventory. Recommendation 4-2. The Air Force should immediately conduct for each TF33-engined weapon system an internal review and competitive re-engining study that looks at fuel savings, operational capabilities, and maintenance costs as figures of merit in order to select the best option. Other Considerations Recommendation 6-5. The Air Force should study optimization and, where it has already done so, accelerate the implementation of optimization in all aspects of its operations, especially as it relates to maintenance and overhaul and to the scheduling of its cargo, passenger, and tanker fleets. Recommendation 6-6. The Air Force should undertake a review of maintenance requirements and how they affect fuel efficiency and/or fuel conservation. Additionally, it should have in place an organizational structure that will have the focus and authority to establish maintenance requirements across all operations. Additionally, the Air Force should undertake a comprehensive review of information systems to assure that repair histories and reliability information are being utilized in a holistic manner and being transmitted to the appropriate organizations—that is, those that have oversight responsibility for efficient operations and the ability to implement the required actions. Critical to this recommendation is the establishment of fleet manager programs to oversee the entire maintenance operation, both line and shops, and the development of a comprehensive information system to monitor the effectiveness of maintenance actions and fleet performance. The ability of an integrated database to inform a cognizant organization that has a say about the outcome of maintenance, whether in the field or in the shop, is a critical factor in achieving operational fuel efficiency. Lastly, the maintenance entity must be organized along the flow of information to assure that there is top-down and bottom-up access to all the information that is required to maintain the equipment.

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Improving the Efficiency of Engines for Large Nonfighter Aircraft Alternative Fuels Recommendation 7-4. DoD should take steps beyond the B-52 flight demonstration to reaffirm its long-term commitment to synthetic fuels for its fleet of aircraft. This includes qualifying an FT fuel specification and fully certifying aircraft re-engined with, for example, CFM56 and large tanker platforms such as the KC-135R/T, C-130, and KC-10. Recommendation 7-6. DoD should, over the period FY08-FY15, put into place a comprehensive program of candidate fuel qualification strategy comprising four phases: R&D, system demonstration, transition and deployment, and operations and support (see Figure 7-3). This work should be funded at $15 million per year. Technology Preparedness and Insertion Recommendation 8-1. The Air Force should review and amend the Versatile Affordable Advanced Turbine Engine (VAATE) plan and its engine development programs, as appropriate, to provide an explicit emphasis on technology to improve fuel efficiency and reduce operational costs, to transition those improvements to fielded, high-bypass-ratio engines, and to consider research aimed at the reduction of particulate, hydrocarbon, sulfur, carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), and noise emissions by the DoD systems. Recommendation 8-4. The Air Force and DoD should reinvigorate the component improvement program (CIP) and the propulsion capability enhancement programs and combine the responsibility for component improvement, sustainment, and fuel burn under one budget authority to allow it to capture opportunities to reduce fuel burn and cost. Recommendation 8-5. The Air Force and DoD should restore turbine engine S&T funding to the original level necessary to execute the VAATE plan (with recommended changes), with particular emphasis on reinvigorating engine demonstration programs aimed at rendering new technologies ready for transition to fielded engines. Acquisition, Financing, and Support Recommendation 9-1. The Air Force should adopt the following options right away: (1) maintaining all commercial derivative engines to FAA standards, (2) competing all maintenance contracts, (3) creating a line item in the defense budget, and (4) implementing a “fuel-savings performance contract” strategy. Recommendation 9-2. The Air Force should aggressively evaluate the following options to determine their true utility: (1) re-engining Air Force aircraft with commercial engines and leasing or reselling the engines when the airframe is retired, (2) creating a spare engine and parts pool, (3) leasing engines on a long-term basis, and (4) leasing engines on a short-term basis.