# Airworthiness Directives; Eurocopter Deutschland GmbH (ECD) Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters
> **Rule** · Final rule. · Published 1995-10-16 · Effective 1995-11-20 · 60 FR 53507
## Document
- **Document number:** 95-25522
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 60 FR 53507
- **Publication date:** 1995-10-16
- **Effective date:** 1995-11-20
- **FAA docket:** Docket No. 94-SW-19-AD
## Abstract

This amendment adopts a new airworthiness directive (AD), applicable to Eurocopter Deutschland GmbH (ECD) (Eurocopter) Model MBB- BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 helicopters, that requires initial and repetitive inspections of the main rotor (M/R) blade upper and lower surfaces for bulging. This amendment is prompted by two reported incidents in which a balance weight became detached from inside the M/R blade structure and migrated toward the tip of the M/R blade. The actions specified by this AD are intended to detect movement of a balance weight and to prevent severe vibrations and a subsequent precautionary landing.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1995/10/16/95-25522/airworthiness-directives-eurocopter-deutschland-gmbh-ecd-model-mbb-bk-117-a-1-a-3-a-4-b-1-b-2-and)
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