# Airworthiness Directives; Eurocopter France Model AS-365N, N1, and N2 Helicopters
> **Rule** · Final rule. · Published 1999-03-09 · Effective 1999-04-13 · 64 FR 11375
## Document
- **Document number:** 99-5726
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 64 FR 11375
- **Publication date:** 1999-03-09
- **Effective date:** 1999-04-13
- **FAA docket:** Docket No. 97-SW-64-AD
## Abstract

This amendment adopts a new airworthiness directive (AD), applicable to Eurocopter France Model AS-365N, N1, and N2 helicopters, that requires inspecting the helicopter to determine if a certain main rotor head frequency adapter (frequency adapter) is installed and, if so, replacing it with an airworthy frequency adapter. This amendment is prompted by a report of disbonding of the metal center section of a frequency adapter from the elastomer on a main rotor head caused by a lack of adherence during the production process. The actions specified by this AD are intended to prevent increased vibrations caused by disbonding of the center section of a frequency adapter from the elastomer and subsequent reduced controllability of the helicopter.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1999/03/09/99-5726/airworthiness-directives-eurocopter-france-model-as-365n-n1-and-n2-helicopters)
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