# Airworthiness Directives; Leonardo S.p.a. Helicopters
> **Rule** · Final rule. · Published 2022-12-27 · Effective 2023-01-31 · 87 FR 79232
## Document
- **Document number:** 2022-28090
- **Category:** airworthiness
- **Manufacturer:** Leonardo S.p.a.
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 87 FR 79232
- **Publication date:** 2022-12-27
- **Effective date:** 2023-01-31
- **FAA docket:** Docket No. FAA-2022-0465
## Abstract

The FAA is superseding Airworthiness Directive (AD) 2021-20-10 for certain Leonardo S.p.a. Model AB139 and AW139 helicopters. AD 2021- 20-10 required removing from service a certain part-numbered main gearbox (MGB) spherical bearing lock nut (lock nut) that is installed on certain part-numbered MGBs and replacing it with a newly designed MGB lock nut. AD 2021-20-10 also prohibited installing any MGB with the affected MGB lock nut and prohibited installing any affected MGB lock nut on any helicopter. Since the FAA issued AD 2021-20-10, it was discovered that a part number (P/N) was incorrectly listed and that the applicability needed to be clarified. This AD retains the requirements of AD 2021-20-10 and clarifies the applicability. The FAA is issuing this AD to address the unsafe condition on these products.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2022/12/27/2022-28090/airworthiness-directives-leonardo-spa-helicopters)
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