Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Eurocopter Deutschland GmbH (Eurocopter) Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 helicopters. This proposal would establish a new retirement life for the clutch and would require an entry into the Accessory Replacement Record indicating the new life limit. This proposal is prompted by a recalculation of life limitations by the part manufacturer, Warner Electric. The clutch manufacturer used the airframe load spectrum to establish the new life limit of 3,600 hours time-in-service (TIS). The actions specified by the proposed AD are intended to prevent failure of the clutch, loss of power to the main rotor and a subsequent forced landing of the helicopter.