Summary
This document proposes to adopt a new airworthiness directive (AD) that would apply to certain Pilatus Aircraft Ltd. Model PC-7 airplanes. The proposed AD would require replacing the rudder and elevator pivot arms with parts of improved design. The proposed AD results from reports of cracks in the elevator and rudder trim tab pivot arms on the above-referenced airplanes. The actions specified by the proposed AD are intended to prevent failure of the elevator and rudder caused by fatigue cracking of the pivot arms, which could result in reduced airplane controllability and possible loss of control of the airplane.