Airworthiness Directive · Amendment 39-13564 · Boeing Model 747-400 and -400D Series Airplanes
Boeing Model 747-400 and -400D Series Airplanes
Model 747-400 and -400D series airplanes, as listed in Boeing Alert Service Bulletin 747-21A2427, dated April 24, 2003; certificated in any category.
This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-400 and -400D series airplanes. This action requires an inspection to determine the routing configuration of wire bundle W4489 and related investigative/corrective actions. This action is necessary to prevent possible interference between wire bundle W4489 and the receptacle housing of the chiller boost fan, drain tubes, and adjacent structure, which could result in damage to the wire bundle and consequent arcing and fire. This action is intended to address the identified unsafe condition.
