Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 777 series airplanes. This proposal would require modification of the supports for the fuel quantity indicator system (FQIS) wire bundles. This action is necessary to prevent chafing of the FQIS wiring on surrounding structures and systems, which could result in exposure of the bare conductor in close proximity to structures or other electrically conductive return paths and a consequent possibility of electrical arcing and explosion in the fuel tank in the event of an additional wiring failure outside the fuel tank. This action is intended to address the identified unsafe condition.