All 20 U.S. F-35 Lightning IIs have been grounded following a failure of the aircraft's integrated power package (IPP).
The incident took place at about 8:30 a.m. Aug. 2 at Edwards Air Force Base, Calif., during a ground maintenance run of aircraft AF-4, the fourth conventional takeoff and landing version of the triservice Joint Strike Fighter. Following the failure of the IPP - which combines the functions performed by an auxiliary power unit, emergency power system and environmental controls - the crew shut down the aircraft as per standard operating procedures, according to a press release by the JSF program office.
There were no injuries.
Government and contractor teams are reviewing the incident to find out what caused the IPP to fail. The program office suspended flight operations as "the prudent action to take at this time until the F-35 engineering, technical and system safety teams fully understand the cause of the incident," according to the statement.
This is the second time the F-35 has been grounded this year due to electrical problems. In March, the F-35 fleet was briefly grounded after the same aircraft experienced a dual generator failure that was traced to faulty maintenance procedures.
The Navy's F-35C was also grounded for six days in June due to a software problem with the wing-fold mechanism that might have caused the flight control surfaces to freeze in flight. The aircraft returned to flight June 23.