Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 757-200, -200CB, and -200PF series airplanes. This proposed AD would require an inspection of each trailing edge flap transmission assembly to determine the part number and serial number, and related investigative and corrective actions and part marking if necessary. This proposed AD is prompted by a report indicating that cracked flap transmission output gears have been discovered during routine overhaul of the trailing edge flap transmission assemblies. We are proposing this AD to prevent an undetected flap skew, which could result in a flap loss, damage to adjacent airplane systems, and consequent reduced controllability of the airplane.