airworthiness · Rule · Final rule. · Published 2021-10-18 · Effective 2021-11-22 · 86 FR 57574
Document
Document number
2021-22468
Federal Register citation
86 FR 57574
Type
Rule
Action
Final rule.
Category
airworthiness
Manufacturer
Leonardo S.p.a.
Publication date
2021-10-18
Effective date
2021-11-22
FAA docket
Docket No. FAA-2021-0579
Abstract
The FAA is adopting a new airworthiness directive (AD) for certain Leonardo S.p.a. Model AB139 and AW139 helicopters. This AD was prompted by a report of several occurrences of a cracked main gearbox (MGB) spherical bearing lock nut (lock nut). This AD requires removing from service a certain part-numbered MGB lock nut that is installed on certain part-numbered MGBs and replacing it with newly designed MGB lock nut. This AD also prohibits installing any MGB with the affected MGB lock nut and prohibits installing any affected MGB lock nut on any helicopter. The FAA is issuing this AD to address the unsafe condition on these products.