Summary
This document proposes to adopt a new airworthiness directive (AD) that would apply to all Pilatus Aircraft Ltd. (Pilatus) Model PC-6 airplanes. This proposed AD would require you to inspect the integral fuel tank wing ribs for cracks and the top and bottom wing skins for distortion and repair before further flight, and accomplish a fuel tank ventilating system installation. 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 cracks in the ribs of the inboard integral fuel tanks in the left and right wings, which could lead to wing failure during flight.