Airworthiness Directives; Boeing Model 747-400 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747- 400 series airplanes. This action requires repetitive inspections to detect damage or deflection of the crew rest heat exchanger, and follow-on actions, if necessary. This amendment is prompted by reports of cracking and buckling of the front edge of the crew rest heat exchanger on several airplanes. The actions specified in this AD are intended to detect and correct damage or deflection of the crew rest heat exchanger, which could result in jamming of the rudder or elevator control cables, and consequent reduced controllability of the airplane.