Summary
This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Pilatus Aircraft Ltd. (Pilatus) PC-6, PC-6/A, PC-6/B, and PC-6/C series airplanes equipped with turbo-prop engines. The proposed action would require modifying the fuel system to improve the venting between the collector tank, the main wing tanks, and the engine. The proposed AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. The actions specified by the proposed AD are intended to prevent engine fuel starvation during maximum climb and descent caused by poor fuel tank venting with low fuel levels, which, if not corrected, could result in a loss of engine power during critical phases of flight.