Flight tests of the tri-service F-35 Joint Strike Fighter are running well ahead of the plan for 2011, with 181 flights completed as of March 25 against a plan of 133. In addition, the productivity of each flight test is increasing, with an average of 7.7 unique test points achieved per flight. The combination of additional test flights above plan and greater-than-expected productivity per flight has enabled the overall test program to complete 1,310 test points — far above the number of 899 planned for this stage in the testing cycle. All three variants of the F-35 are being tested, with the average aircraft performing six flights per month.
The test program might have been dealt a serious setback on March 9 when a conventional takeoff variant was forced to make an emergency landing due to a dual generator failure. Generators provide the electricity that starts the fighter’s engine and powers flight controls. However, the cause of the failure was quickly traced to faulty maintenance procedures which have now been corrected, and the test fleet has returned to service. These kinds of anomalies are commonplace in tests of new aircraft.
Lockheed Martin officials are confident they can resolve problems identified in testing with several parts of the short-takeoff/vertical-landing (STOVL) version of the F-35 being developed for the Marine Corps. Among the fixes required are a strengthening of the doors above the mid-fuselage lift-fan, reinforcement of a bulkhead, and resolution of excessive heat deposition at one point near the engine exhaust. Defense secretary Robert Gates recently put the Marine variant on a two-year probationary period to make the necessary fixes, while stating the Air Force and Navy variants were progressing well.
The conventional-takeoff Air Force version will be the most heavily produced F-35, comprising over 70 percent of the domestic production run and almost all of the export sales. The Air Force plans to buy 1,763 conventional-takeoff F-35s, while the Navy and Marine Corps collectively will buy 680 of their two variants. Overseas allies are expected to buy thousands of the planes over the next three decades as they replace aging Cold War fighters and seek a low-cost solution to their requirement for a versatile and survivable tactical aircraft.
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