This AD requires an inspection to determine airplane configuration and part numbers of the landing gear control interface unit and main landing gear (MLG) door actuators; and, for affected airplanes, repetitive inspections of the opening sequence of the MLG door actuator, and replacement of the MLG door actuator if necessary.
This AD also provides optional terminating action for the repetitive inspections. This AD was prompted by a report of a MLG failing to extend during landing, and a determination that a certain configuration of landing gear control interface unit and actuators may result in masking of centralized fault display system messages that are necessary to mitigate risks associated with failure of MLG extension or downlocking.
We are issuing this AD to detect and correct such a configuration, which could prevent the full extension or down-locking of the MLG, possibly resulting in MLG collapse during landing and consequent damage to the airplane and injury to occupants.
This AD becomes effective August 23, 2013.