The F-35 Joint Program Office authorized a return to ground operations for the F-35 developmental test (DT) aircraft today. This is the first step in returning the F-35 fleet to full flight operations. A precautionary suspension of both ground and flight operations for the program was issued Aug. 3.
An Air Force Safety Investigation Board convened Aug. 4 and is reviewing the circumstances that led to the failure of the Integrated Power Package (IPP) aboard AF-4, an F-35A conventional takeoff and landing (CTOL) variant, assigned to Edwards AFB, Calif. The F-35’s IPP is a turbo-machine that provides power to start the engine and generates cooling for the aircraft.
While the investigation continues, government and contractor engineering teams, after reviewing initial data, determined the fleet could safely resume DT ground operations. Preliminary root cause indicates that a control valve did not function properly which led to the IPP failure. Monitoring of this valve is the mitigating action to allow DT ground operations. The F-35 team is revising ground monitoring procedures to ensure testing involving the IPP takes place safely.
While initiating DT ground operations is a major step for the F-35 fleet returning to flight, further reviews are required prior to lifting the suspension of flight operations for the 20 F-35s currently in flying status. These aircraft are part of the System Development and Demonstration (SDD) and Low Rate Initial Production fleet.
The determinations of root cause and potential mitigating actions have the highest priority of the F-35 Team. The impact to SDD execution and production operations is being assessed. The program has built margin into the test schedule to accommodate incidents that occur in the development effort.
Periodic updates concerning this situation will be released as warranted.
