Airworthiness Directives; Boeing Model 757-200 Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 757-200 series airplanes. This AD requires modifying the frequency converters located in the closet assembly in the passenger compartment, and making various wiring changes in and between the closet assembly and forward purser work station. This AD also requires modifying the in-flight entertainment system prior to or concurrently with the modification of the frequency converters. This AD is prompted by a certification review that revealed a frequency converter failure mode not identified in the original system design. We are issuing this AD to prevent a short circuit between the frequency converter output and the distribution circuit breakers, which could result in overheating and failure of adjacent wiring and consequent adverse effects on other systems sharing the affected wire bundle.