# Airworthiness Directives; Airbus Helicopters
> **Rule** · Final rule. · Published 2022-01-05 · Effective 2022-02-09 · 87 FR 385
## Document
- **Document number:** 2021-28471
- **Category:** airworthiness
- **Manufacturer:** Airbus
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 87 FR 385
- **Publication date:** 2022-01-05
- **Effective date:** 2022-02-09
- **FAA docket:** Docket No. FAA-2021-0839
## Abstract

The FAA is superseding Airworthiness Directive (AD) 2020-21-01 for certain Airbus Helicopters Model AS-365N2, AS 365N3, EC 155B, EC155B1, and SA-365N1 helicopters. AD 2020-21-01 required 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 MGB T/R drive flange. This AD continues to require modifying the MGB T/R drive flange installation, and includes additional helicopters in the applicability for the required actions. The FAA is issuing this AD to address the unsafe condition on these products.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2022/01/05/2021-28471/airworthiness-directives-airbus-helicopters)
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