I hope it's not another manufacturing defect:
27 oct 2016: 168057 F-35B USMC 'The fire was due to a "faulty bracket, which was known as a potential hazard by officials overseeing the F-35 program, grazed electrical wiring near hydraulic lines. A fire erupted when an electrical short ignited a small hydraulic leak."'
28 sep 2018 168719 F-35B USMC “An investigation determined a manufacturing defect caused an engine fuel tube to rupture during flight, resulting in a loss of power to the engine"