B-52 Stratofortress Service Life
Updated with modern technology, the B-52 will continue into the 21st century as an important element of US forces. There is a proposal under consideration to re-engine the remaining B-52H aircraft to extend the service life. B-52 re-engine plans, if implemented, call for the B-52 to be utilized through 2025. Current engineering analysis show the B-52's life span to extend beyond the year 2040. The limiting factor of the B-52's service life is the economic limit of the aircraft's upper wing surface, calculated to be approximately 32,500 to 37,500 flight hours. Based on the projected economic service life and forecast mishap rates, the Air Force will be unable to maintain the requirement of 62 aircraft by 2044, after 84 years in service
The May 1997 Report of the Quadrennial Defense Review (QDR), prescribed a total fleet of 187 bombers (95 B-1, 21 B-2, and 71 B-52). Since the QDR, two B-1s had been lost in peacetime accidents. However, the Report of the Panel to Review Long-Range Air Power (LRAP) concluded the existing bomber fleet cannot be sustained through the expected life of the air frames and that additional aircraft will eventually be required. To address this issue, the Air Force will add five additional B-52 attrition reserve aircraft, bringing the B-52 total from 71 to 76 for a total bomber force of 190. The B-52 fleet will remain the same with 44 combat-coded aircraft.
Since those studies, the Air Force has decided to retire 33 B-1s and 17 B-52Hs, reducing the current fleet of 208 bombers (93 B-1s, 21 B-2s, 94 B-52Hs) to 157. Of these bombers, only 96 will be combat coded, with the rest used for backup and other purposes. The B-52H and B-2 still retain a conventional and a nuclear mission, while the B-1 is roled for the conventional mission only.
The B-52H was designed as high altitude aircraft, but was adapted to low level tactical maneuvers in 1960's. A number of structural improvements were made during the 1960s and 1970s to equip it to fly the more demanding low- level mission and to address other structural issues.
The airframe life for the current fleet is estimated to be between 32,500 and 37,500 hours, depending on the usage history of the individual aircraft. The estimate is based upon scaling measurements from a full-scale test structure using assumed mission profiles along with historical and projected usage information. The upper wing surface is expected to be the life- limiting structural member. As of 1999 the average airframe had 14,700 flight hours. Boeing believes with high confidence that the average number of flight hours left is 17,800, at a minimum. The "oldest" B-52H is at about 21,000 hours and only experiences about 380 flight hours per year.
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