B-52 Stratofortress Re-Engine - 2002
In June 2002, USD(AT&L) commissioned a Defense Science Board [DSB] task force to advise on the key issues associated with re-engining the B-52H Stratofortress. This was the fourth B-52H re-engining study conducted since 1996. In the three years since completion of the previous study, cost, operational and business factors relevant to a re-engining decision have changed substantially. In order to compare the projected maintenance of the TF33-103 with proposed replacements, the task force received briefings from 3 COTS engine manufacturers with engines that appear suitable for use on the B-52H; the Rolls-Royce RB-211, the Pratt & Whitney PW 2040, and 3 options from General Electric.
Engine removal rates for today's commercial engines are very low. This is primarily a function of the technical advances made in engines over the past 30 years. Today's new commercial engines can last 10,000 to 15,000 hours between initial installation and first off-wing repair. For the B-52H re-engining, the time interval between installation and first off-wing repair is projected to be greater than the remaining hours left on the airframe, making re-engining essentially a "hang and forget" program.
This was the fourth B-52H re-engining study conducted since 1996. The first three Air Force studies concluded re-engining was not economically justifiable. Several factors drove this conclusion: use of a constant fuel price at the Defense Energy Support Center's (DESC) rate; Air Force Material Command's estimate that engine depot cost would be stable through 2037; and the organizational judgment that required funding would not compete successfully against higher priorities. In addition, premature B-52H retirement and force reductions were considered program risks.
In the three yeare since completion ofthe previous study, cost, operational and business factors relevant to a re-engining decision had changed substantially. A 2001 DSB study calculated the cost of fuel delivered in-flight to be $17.50 per gallon, using USAF provided figures, excluding the capital cost oftankers. Previous studies valued all fuel at about one dollar per gallon. The actual depot price for TF33-103 maintenance was now nearly triple previous estimates; and the cost continued to rise. Further, the primary assigned aircraft (PAA) bomber force had been reduced from 130 to 96, making further material force reductions less likely.
Previous Air Force studies, using Air Force Material Command figures, estimated the depot overhaul cost of a TF33-103 engine to be $257K (FY96$). Further, previous studies assumed cost would remain relatively constant over the remainder ofthe weapon system's life (until about 2037) and would never exceed $300K. This estimate is no longer valid. Between 1996 and 2001, the per-engine overhaul price rose from $257K to $539K. The current FY03 price is $710K-an increase of 176% since 1996. Currently, Boeing and the B-52H System Program Office estimate that an annual real cost growth of 2% over the remaining economic life ofthe airframe is a reasonable planning assumption, putting the depot cost for each engine at about $ 1.4M by 2037.
Long-term experience with TF33-103 engine reliability indicates that approximately 87 engines will be removed from the current B-52H fleet each year for depot overhaul. On the other hand, today's new commercial turbofan engines are so reliable that the task force estimates that in a re-engined B-52H fleet, no engine removals would be necessary for the remainder of the B-52H's economic life unless caused by unforeseen failures, such as severe foreign object damage (FOD), combat damage, or equipment defects. As a result, all engine work would be "on pylon" for the remaining life of the B-52H fleet. This has significant implications for depot capability, logistics provisioning and maintenance manning. Current widespread commercial use of these engines would also minimize the need to pre-purchase spares.
Direct costs, such as fuel and maintenance, are easily quatified in a cost-benefit spreadsheet analysis. Operational value is not. A re-engined B-52H delivers a significant increase in unreflieled range, reduces demand for fuel and tanker assets, and increases loiter time. Recent changes in the threat environment, new operational applications for the B-52H, and changing future mission utilization concepts also increase the operational value of re-engining.
The 2002 DSB task force concluded that the economic and operational benefits far outweigh the program cost; and unanimously recommended the Air Force proceed with B-52H re-engining without delay.
|
NEWSLETTER
|
| Join the GlobalSecurity.org mailing list |
|
|
|
