Airworthiness Directives; Pilatus Aircraft Ltd. Model PC-7 Airplanes

This amendment supersedes Airworthiness Directive (AD) 98-08- 07, which currently requires replacing the rudder and elevator pivot arms with parts of improved design on certain Pilatus Aircraft Ltd. (Pilatus) Model PC-7 airplanes. This AD requires replacing the rudder and elevator pivot arms with parts that have been improved since issuance of AD 98-08-07. This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. The actions specified by this 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.