# Airworthiness Directives; Airbus Helicopters
> **Rule** · Final rule. · Published 2020-10-08 · Effective 2020-11-12 · 85 FR 63440
## Document
- **Document number:** 2020-22241
- **Category:** airworthiness
- **Manufacturer:** Airbus
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 85 FR 63440
- **Publication date:** 2020-10-08
- **Effective date:** 2020-11-12
- **FAA docket:** Docket No. FAA-2020-0410
## Abstract

The FAA is adopting a new airworthiness directive (AD) for certain Airbus Helicopters Model AS-365N2, AS 365N3, EC 155B, EC155B1, and SA-365N1 helicopters. This AD requires modifying the main gearbox (MGB) tail rotor (T/R) drive flange installation. This AD was prompted by several reported occurrences of loss of tightening torque of the Shur-Lok nut, which serves as a retainer of the T/R drive flange. The actions of this AD are intended to address an unsafe condition on these products.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2020/10/08/2020-22241/airworthiness-directives-airbus-helicopters)
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