Airworthiness Directives; Boeing Model 747-400, -400D, and -400F Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-400, -400D, and -400F series airplanes, that requires modification of the P212 and P213 panels of the cabin pressure control system. For certain airplanes, this amendment also requires modification of the P5, P6, and P7 panels, and the W4701, W4703, and W4908 wire bundles, as applicable. This amendment is prompted by a report of in-flight loss of cabin pressurization control due to a single failure of the auxiliary power unit (APU) battery. The actions specified by this AD are intended to prevent loss of control of the cabin pressurization system, which could result in rapid depressurization of the airplane. Such rapid depressurization could result in deleterious physiological effects on the passengers and crew; and airplane diversions, which represent an increased risk to the airplane, passengers, and crew.