Summary
This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Pilatus Aircraft Ltd. (Pilatus) Models PC-12 and PC-12/45 airplanes. The proposed AD would require inspecting all flap actuators in the internal gear system to assure that correct end-play and backlash measurements exist, and accomplishing any corrective adjustments as necessary. The proposed AD would also require incorporating a temporary revision into the Pilot's Operating Handbook (POH) in order to update operating procedures for the flap actuators; and would require incorporating temporary revisions to the maintenance manual in order to make the proposed inspection part of the future maintenance program. 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 premature wear of the internal gear system caused by excessive backlash in the flight control flap actuators, which could eventually result in loss of actuator output with possible reduced or loss of airplane control.