Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9-80 series airplanes and Model MD-88 airplanes, that currently requires a revision to the FAA-approved Airplane Flight Manual (AFM) which specifies that autothrottles must be disconnected if engine surge (stall) is detected during takeoff. That AD was prompted by results of an accident investigation, which revealed that the digital flight guidance computer (DFGC) on these airplanes can incorrectly identify an engine surge or stall as being an engine failure. This can cause the autothrottles to unclamp and automatically advance the thrust levers during takeoff. The actions specified in that AD are intended to prevent automatic advance of the thrust lever on a surging engine during takeoff, which could cause engine failure. This action would require the installation of a modified DFGC's which, when accomplished, would terminate the requirement for the AFM revision.