Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 767-400ER series airplanes. This proposed AD was prompted by reports of turbine wheel bursts in the air driven pump (ADP) turbine gearbox assembly (TGA), which resulted in the release of high energy fragments. This proposed AD would require replacing the existing ADP TGA with an improved ADP TGA. We are proposing this AD to prevent fragments from an uncontained turbine wheel burst penetrating the fuselage and striking passengers, or penetrating the wing-to-body fairing and striking ground handling or maintenance personnel, causing serious injury.