Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-11 and -11F airplanes, that currently requires repetitive inspections to verify operation of the remote control circuit breakers (RCCB) of the alternating current (AC) cabin bus switch, and replacement of any discrepant RCCB with a new RCCB. This action would require the existing actions per a later service bulletin revision. The actions specified by the proposed AD are intended to prevent propagation of smoke and fumes in the cockpit and passenger cabin due to an inoperable RCCB of the AC cabin bus switch during smoke and fume isolation procedures. This action is intended to address the identified unsafe condition.