Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to all McDonnell Douglas Model DC-9-80 series airplanes, Model MD-88 airplanes, and Model MD-90 airplanes, that currently requires revising the Airplane Flight Manual (AFM) to include limitations and procedures to address situations in which the autopilot or autothrottle fails to disengage. That AD was prompted by incidents in which the flightcrew was unable to disconnect the autopilot or autothrottle function from the engaged position, due to a discrepancy in a microswitch that is associated with the operation of those functions. This action would require an inspection of the autopilot and autothrottle engage switches located in the flight guidance control panel, and installation of improved switches. Accomplishment of these actions would terminate the previous requirement for the AFM revision. The actions specified by the proposed AD are intended to ensure that the autopilot and autothrottle disengage when commanded to do so by the flightcrew.