Military Airlift: C-17 Flap Requires Additional Testing

GAO discussed the status of the design and testing of wing flaps for the Air Force's C-17 military transport aircraft. GAO noted that: (1) tests conducted in February 1991 showed that the wing flaps could be subjected to twice the temperature for which they were originally designed; (2) contractor testing yielded an estimated flap life expectancy of about 400 hours, but did not consider the effects of temperature; and (3) limited acoustic data collected during flight testing of ground and flight aircraft indicate that the strengthened flap will be exposed to a lower level of acoustic stress than was believed. GAO also noted that: (1) it believes that the Air Force and contractor should establish test plans to determine whether the flaps meet the contract service life requirement before entering full-rate production; (2) the Air Force concluded that the final flap design should be tested for life expectancy through a combined heat and acoustic environment test; (3) the contractor believes that its tests have already demonstrated the flap's ability to operate in the expected temperature and acoustic environment; (4) the Department of Defense believes that testing it has conducted or already plans to conduct precludes the necessity of conducting specific life expectancy testing; and (5) current plans to acquire actual acoustic and temperature environment data from flight test and developmental and operational tests will help to assess aircraft performance, but those tests will not yield flap life expectancy estimates.