Summary
The FAA proposes to supersede Airworthiness Directive (AD) 2002-01-09, which applies to all Pilatus Aircraft Ltd. (Pilatus) Models PC-7, PC-12, and PC-12/45 airplanes that incorporate a certain engine-driven pump. AD 2002-01-09 currently requires you to inspect the joints between the engine-driven pump housing, the relief valve housing, and the relief valve cover for signs of fuel leakage and extruding gasket material; replace any engine-driven pump with any of the above problems; and 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. This proposed AD would retain the actions from AD 2002-01-09, would add certain engine-driven pumps to the applicability, and would require eventual replacement of the pump with an improved design pump to assure that the unsafe condition does not recur. We areissuing this proposed AD to detect and correct gasket material extruding from the engine-driven pump housing and detect and correct relief valve attachment screws with inadequate torque. These conditions could lead to fuel leakage and result in a fire in the engine compartment.