Summary
We propose to adopt a new airworthiness directive (AD) for the Eurocopter Deutschland GmbH (Eurocopter) Model MBB-BK 117 C-2 helicopters. This proposed AD would require changing the direction of the bolt connecting the upper clevis bolt of a specific bellcrank in the main rotor assembly, repetitively inspecting the bearings in the bellcrank assemblies for correct staking, and replacing a bellcrank if a bearing is staked incorrectly. This proposed AD is prompted by improperly staked bellcrank bearings, which may cause the bellcrank to shift in the axial direction and cause chafing. The proposed actions are intended to prevent contact between the bolts on certain main rotor bellcranks, which could result in chafing and subsequent loss of control of the helicopter.