"[Unanticipated] extra heat is increasing the wear on the engine, reducing the engine's life, and adding a projected $38 billion in maintenance costs over the life of the aircraft," the GAO report said on Tuesday.
Also, the ambitious $10 billion Block 4 program to modernize the aircraft to enable it meet challenges from major peer competitor nations led by Russia and China over the coming decade has been further delayed and will cost 60% more than its original expensive price tag, the GAO said.
Also, Department of Defense F-35 Joint Program Office (JPO) Director US Air Force Lieutenant General Michael Schmidt told a House Armed services subcommittee hearing on Tuesday that he still could not predict when problems with the $1.6 billion Technology Refresh-3 (TR-3) cockpit electronics software upgrade for the F-35 that has halted new aircraft deliveries since July will be corrected.