Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 767 and 777 airplanes. This proposed AD was prompted by reports of uncommanded door closure of the large lower lobe cargo door. This proposed AD would require inspecting for part numbers and serial numbers of the rotary actuators of the large forward and aft lower lobe cargo doors, as applicable, and corrective action if necessary. We are proposing this AD to detect and correct rotary actuators made with a material having poor actuator gear wear characteristics, which could result in failure of the rotary actuators for the large forward or aft lower lobe cargo door and subsequent uncommanded door closure, which could possibly result in injury to people on the ground.