Airworthiness Directives; Boeing Model 747-400 and -400F Series Airplanes Equipped With Rolls Royce Engines

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-400 and -400F series airplanes. This action requires repetitive inspections for damage or arcing of the power feeder cables and conduit of the integrated drive generator (IDG) in the forward section of all four struts, and repair if necessary. This action also requires repetitive inspections for chafing damage or arcing of the adjacent hydraulic lines in the aft section of the outboard struts. Additionally, this action requires eventual terminating actions for the repetitive inspections. This action is necessary to prevent damage and arcing to the conduit and power feeder cables of the IDG, which could result in a fire in the engine strut; and to prevent damage to the adjacent hydraulic lines in the aft section of the outboard struts, which could result in reduced controllability of the airplane. This action is intended to address the identified unsafe condition.