Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Beech Model 400, 400A, and 400T (military T-1A) airplanes. This proposal would require modification of the standby instrument lighting system. This proposal is prompted by a report that, due to the design of the standby instrument lighting system, the lighting for the standby instruments dimmed to an unacceptable level when the main electrical power was turned off. The actions specified by the proposed AD are intended to ensure that the standby instrument lighting system adequately illuminates the standby instrument, if normal electrical power is lost or is turned off as a result of fire or smoke in the cockpit.