Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747-400 series airplanes. This proposal would require removal and reconfiguration of the battery grounds of the auxiliary power unit (APU). This proposal is prompted by reports of smoke or fire coming from the APU due to battery grounds that were not installed or maintained properly. The actions specified by the proposed AD are intended to prevent overheating and heat damage of the APU battery grounds due to improper installation of the APU battery ground, which could result in heat damage and consequent smoke or fire on the airplane.