Eighteen of the 20 F-35 JSF aircraft currently flying were authorised to return to flight last week following a two and a half week grounding.
The F-35 fleet was grounded on August 4 following the failure of an Integrated Power Pack (IPP) on development aircraft AF-4 at Edwards AFB. The JSF Program Office says a valve in the IPP did not function properly.
“Monitoring of valve position is a mitigating action to allow monitored operations,” JPO spokesman Joe DellaVedova said in a statement. “A permanent resolution is in work. The F-35’s Integrated Power Package is a turbo-machine that provides power to start the engine and generates cooling for the aircraft. The government and contractor engineering teams determined the program could resume developmental test flight operations while the investigation continues. This assessment was made after reviewing data from ground and flight tests which showed, with revised test monitoring procedures governing the IPP, the aircraft can be flown safely.”
The two F-35As delivered to Eglin AFB for training have not yet been cleared to return to flight as they are not instrumented.
Meanwhile, F-35C test aircraft CF-1 with an F/A-18E Super Hornet undertook jet blast deflector (JBD) testing at Lakehurst, New Jersey, on August 13. The testing was “to assess the integration of F-35s in aircraft carrier launch operations”, according to the JPO.