Airworthiness Directives; Boeing Model 737-300, -400, -500, -600, -700, -700C, -800, and -900, and 747-400 Series Airplanes; and Model 757, 767, and 777 Airplanes

摘要

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 737-300, -400, -500, -600, -700, -700C, -800, and -900, and 747-400 series airplanes; and Model 757, 767, and 777 airplanes. This AD requires modifying the static inverter by replacing resistor R170 with a new resistor and relocating the new resistor. This AD results from evaluation of the carbon resistor, which revealed a failure mode that can cause the resistor to ignite, involving adjacent capacitors as well. We are issuing this AD to prevent a standby static inverter from overheating, which could result in smoke in the flight deck and cabin and loss of the electrical standby power system.