Airworthiness Directives; Cessna Model 750 Citation X Series Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to all Cessna Model 750 Citation X series airplanes. This action requires repetitive in-flight functional tests to verify proper operation of the secondary horizontal stabilizer pitch trim system, and repair, if necessary. This amendment is prompted by reports of simultaneous failures of the primary and secondary horizontal stabilizer pitch trim system during flight, due to internal water contamination and corrosion damage in the system actuator. The actions specified in this AD are intended to detect and correct such contamination and damage, which could result in simultaneous failure of both primary and secondary pitch trim systems, and consequent reduced controllability of the airplane.