# Airworthiness Directives; Airbus Helicopters Deutschland GmbH Helicopters
> **Rule** · Final rule. · Published 2021-07-14 · Effective 2021-08-18 · 86 FR 37017
## Document
- **Document number:** 2021-14925
- **Category:** airworthiness
- **Manufacturer:** Airbus
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 86 FR 37017
- **Publication date:** 2021-07-14
- **Effective date:** 2021-08-18
- **FAA docket:** Docket No. FAA-2021-0335
## Abstract

The FAA is adopting a new airworthiness directive (AD) for all Airbus Helicopters Deutschland GmbH Model 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 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 AD requires inspections to determine if any bolted main rotor blades are installed, and replacement of the affected main rotor blades. The FAA is issuing this AD to address the unsafe condition on these products.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2021/07/14/2021-14925/airworthiness-directives-airbus-helicopters-deutschland-gmbh-helicopters)
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