# Airworthiness Directives; Eurocopter Deutschland GmbH Model MBB- BK 117 A-1, A-3, A-4, B-1, B-2 and C-1 Helicopters
> **Rule** · Final rule. · Published 1997-11-05 · 62 FR 59780
## Document
- **Document number:** 97-29238
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 62 FR 59780
- **Publication date:** 1997-11-05
- **FAA docket:** Docket No. 96-SW-23-AD
## Abstract

This amendment adopts a new airworthiness directive (AD), applicable to Eurocopter Deutschland GmbH (Eurocopter) Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 helicopters, that establishes a new retirement life for the clutch and requires an entry into the Accessory Replacement Record indicating the new life limit. This amendment 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 this AD are intended to prevent failure of the clutch, loss of power to the main rotor and a subsequent forced landing of the helicopter.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1997/11/05/97-29238/airworthiness-directives-eurocopter-deutschland-gmbh-model-mbb--bk-117-a-1-a-3-a-4-b-1-b-2-and-c-1)
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