AD FAA-2021-0335

The FAA proposes to adopt a new airworthiness directive (AD) for all Airbus Helicopters Deutschland GmbH MBB-BK 117 A-1, MBB-BK 117 A-3, MBB-BK 117 A-4, MBB-BK 117 B-1, MBB-BK 117 B-2, and MBB-BK 117 C-1 helicopters. This proposed AD was prompted by a report of sudden severe vibrations and a cracked open blade trailing edge caused by a loosened lead inner weight. This proposed AD would require inspections to determine if any bolted main rotor blades are installed, and replacement of the affected main rotor blades. The FAA is proposing this AD to address the unsafe condition on these products.