The Joint Strike Fighter program office just out the following update on F-35 flight testing:
AF-4, a F-35 System Development and Demonstration (SDD) aircraft, experienced a dual generator failure and oil leak while conducting flight test operations March 9 at Edwards AFB, CA. The test pilot was able to return the jet safely back to Edwards AFB. As a safety precaution, a Suspension to Operations (STOP) was issued on March 10 until the root cause of this occurrence was determined.
Since the incident, the F-35 Joint Program Office, Air Force and Navy System Commands and Lockheed Martin have collaborated to determine the root cause. The failed generators from AF-4 were inspected over the weekend. On the basis of that effort, and in combination with flight test data from the incident, it was determined that the dual generator failure was the result of a design artifact unique to a newer configuration of the generator.
The current F-35 fleet has two generator configurations. The newer generator had production initiated on AF-4, BF-5, and CF-1. As a result of our understanding of what system failed and the contributing factors, the Joint Program Office has rescinded the STOP today for aircraft flying the older generator configuration (AF-1/2/3, BF-1/2/3/4). The Suspension to Operations continues for the balance of the SDD fleet and all Low Rate Initial Production (LRIP) aircraft in flight ops configured with the newer generator.
Determination of root cause and potential mitigating actions has the highest priority on the F-35 Team. Impact to SDD execution and production ops is being assessed.