airworthiness · Rule · Final rule. · Published 2021-08-24 · Effective 2021-09-28 · 86 FR 47215
Document
Document number
2021-18165
Federal Register citation
86 FR 47215
Type
Rule
Action
Final rule.
Category
airworthiness
Publication date
2021-08-24
Effective date
2021-09-28
FAA docket
Docket No. FAA-2019-0597
Abstract
The FAA is superseding Airworthiness Directive (AD) 2019-12-05 for certain CFM International S.A. (CFM) CFM56-5B, CFM56-5C, and CFM56- 7B model turbofan engines with a certain rotating air high-pressure turbine (HPT) front seal. AD 2019-12-05 required replacement of the affected rotating air HPT front seal with a part eligible for installation. This AD was prompted by cracks found in the rotating air HPT front seal. This AD requires replacement of affected rotating air HPT front seals installed on CFM CFM56-5B, CFM56-5C, and CFM56-7B model turbofan engines that have fewer cycles since being reconfigured than the engines affected by AD 2019-12-05. This AD also requires CFM56-5B or CFM56-7B model turbofan engines with a reconfigured rotating air HPT front seal that was previously operated in a CFM56-5C model turbofan engine to follow the removal requirements for the CFM56-5C model turbofan engine. The FAA is issuing this AD to address the unsafe condition on these products.