F-35 flight operations have been cleared to resume following engineering analysis of the turbine blade which developed a crack. This decision concludes a cautionary flight suspension that began on Feb. 21 after a 0.6 inch crack was found on a third stage turbine blade of a test aircraft at the Edwards Air Force Base F-35 Integrated Test Facility during a routine inspection.
Comprehensive tests on the blade were conducted at the Pratt & Whitney facility in Middletown, Conn. The engine in question is part of the F-35 test aircraft fleet and had been operated for extended time in the high-temperature environment in its mission to expand the F-35 flight envelope. Prolonged exposure to high levels of heat and other operational stressors on this specific engine were determined to be the cause of the crack.
No additional cracks were found during inspections of the remaining F135 inventory. Within the current DoD inventory, 17 F-35s are employed in test and development at Patuxent River Naval Air Station and Edwards Air Force Base; the remaining aircraft are assigned to Eglin Air Force Base and Marine Corps Air Station Yuma, and comprise the initial F-35 training fleet.