Two systems, including the Honeywell-supplied integrated power package (IPP) linked to a previous aircraft fire, failed as a fire erupted inside the weapons bay of a US Marine Corps Lockheed Martin F-35B on a 27 October training mission.

Sensors onboard the aircraft detected a fire in the right weapons bay and failures of the IPP and a hydraulics system while the aircraft was flying in the airport's landing pattern, according to a mishap report released by the Naval Safety Center.

The center has classified the incident as a class A mishap, meaning the aircraft suffered at least $2 million in damages, but the results of the investigation could change the cost estimate, the USMC tells FlightGlobal. The Marines have not ordered a precautionary safety stand-down for the F-35B fleet.

The pilot assigned to VMFAT-501 at MCAS Beaufort, South Carolina, landed safely without injuries or further incident, the USMC adds.

Honeywell's IPP is used to start the F-35's engine on the ground and supply emergency power in the air. It is also used to drive the aircraft's environmental control system.

Another IPP fire aboard an F-35A grounded the F-35 test fleet in 2011. That investigation linked the IPP fire in the AF-4 test aircraft to a critical valve failure.