Airworthiness Directives; Boeing Model 747-400 Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 747-400 series airplanes. This AD requires repetitive inspections to detect discrepancies of the forward and rear heat exchanger shells of the air distribution system of the crew rest area, and applicable corrective actions. This AD also requires an inspection to identify the part number, shop code, and build date of the forward and rear heat exchanger shells of the air distribution system of the crew rest area, and applicable corrective actions, which end the repetitive inspections. This AD results from a report of an uncommanded up and down pitch movement of an airplane in flight and resistance in the elevator controls on the ground during taxi. We are issuing this AD to prevent cracking and buckling of the forward or rear heat exchanger shell of the air distribution system of the crew rest area, which could result in jamming of the rudder and/or elevator control cables and consequent reduced controllability of the airplane.