Airworthiness Directives; Honeywell Flight Management Systems (FMSs) Equipped With Honeywell NZ-2000 Navigation Computers and Honeywell IC-800 or IC-800E Integrated Avionics Computers; as Installed on Various Transport Category Airplanes

The FAA is superseding an existing airworthiness directive (AD), which applies to all Honeywell FMSs served by Honeywell NZ-2000 navigation computers and IC-800 integrated avionics computers. That AD currently requires identifying affected computers by part number and software modification level and revising the Limitations section of applicable airplane flight manuals to provide procedures for retaining optimum position determination and intended navigation. This new AD requires upgrading new software, which terminates the existing requirements. This AD results from reports of in-flight unannunciated shifts of computed position in airplanes with the subject FMS computers. We are issuing this AD to prevent a shift in the FMS computed position, which could result in uncommanded deviations from the intended flight path of the airplane, and, if those deviations are undetected by the flight crew, compromised terrain/traffic avoidance.