Summary
We propose to adopt a new airworthiness directive (AD) for all The Boeing Company Model 767 airplanes. This proposed AD was prompted by a report of a rotary actuator for the trailing edge (TE) flap that had slipped relative to its mating reaction ring, which is attached to the flap support rib. This proposed AD would require repetitive inspections for corrosion of the fixed ring gear and reaction ring splines of the rotary actuator assembly for each support position, and related investigative and corrective actions if necessary. We are proposing this AD to detect and correct reaction ring gears and rotary actuator gears from becoming disengaged with flaps extended and causing an uncommanded roll due to flap blowback, overload, or flap departure from the airplane, which could compromise safe flight and landing of the airplane.