Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain McDonnell Douglas Model MD-11 series airplanes. The existing AD currently requires a revision of the airplane flight manual (AFM) to alert the flightcrew that both flight management computers (FMC) must be installed and operational. The existing AD also requires an inspection to determine the serial number of the FMCs; and follow-on corrective actions, if necessary, which terminate the AFM revision. The existing AD also requires an inspection to verify if a certain modification is on the identification plates of the FMCs; and applicable follow-on and corrective actions. This proposed AD would require installation of upgraded flight management computer software, which would terminate the existing AD. This proposed AD would also add airplanes to the applicability, including adding Model MD-10-10F and MD-10-30F airplanes. This proposed AD results from a report that the FMC does not acknowledge the pre-set glareshield control panel (GCP) altitude when profile (PROF) mode is engaged in descent mode. We are proposing this AD to prevent the un-commanded descent of an airplane below the selected level-off altitude, which could result in an unacceptable reduction in the separation between the airplane and nearby air traffic or terrain.