Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede two existing airworthiness directives (AD) that apply to all The Boeing Company Model 767 airplanes. One AD currently requires a functional check of the shear rivets in all six elevator power control actuator (PCA) bellcrank assemblies to determine the condition of the shear rivets, and replacement or rework of the bellcrank assemblies if necessary. The other AD currently requires repetitive testing of the elevator control system to determine if an elevator PCA is rigged incorrectly, and follow-on actions if necessary. Since we issued those ADs, a terminating modification has been designed. This proposed AD would require an inspection to determine the part numbers and condition of the bellcrank assemblies; modification or replacement of the PCA bellcrank assembly, if necessary; and a repetitive functional test and mis-rig check, and corrective actions if necessary. We are proposing this AD to prevent continued operation with yielded or failed shear rivets in the elevator PCA bellcrank assemblies, and to prevent certain failures or jams in the elevator system from causing a hardover of the elevator surface, resulting in a significant pitch upset and possible loss of control of the airplane.