Summary
This document proposes to adopt a new airworthiness directive (AD) that would apply to all Pilatus Aircraft Ltd. Models PC-7, PC-12, and PC-12/45 airplanes that incorporate a certain engine-driven pump. This proposed AD would require you to: inspect the joints between the engine-driven pump housing, relief valve housing, and the relief-valve cover for signs of fuel leakage or extruding gasket material; replace any engine-driven pump with signs of fuel leakage or extruding gasket material; and inspect to ensure that the relief valve attachment screws are adequately torqued and re-torque as necessary. This proposed AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. The actions specified by this proposed AD are intended to detect and correct gasket material extruding from the engine-driven pump housing and detect and correct relief valve attachment screws with inadequate torque. Such conditions could lead to fuel leakage and result in a fire in the engine compartment.