# Airworthiness Directives; Lycoming Engines Model IO-720-A1B Reciprocating Engines
> **Rule** · Final rule; request for comments. · Published 2011-09-14 · Effective 2011-09-29 · 76 FR 56637
## Document
- **Document number:** 2011-22244
- **Category:** airworthiness
- **Manufacturer:** Lycoming
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 76 FR 56637
- **Publication date:** 2011-09-14
- **Effective date:** 2011-09-29
- **FAA docket:** Docket No. FAA-2011-0604
## Abstract

We are adopting a new airworthiness directive (AD) for certain model IO-720-A1B Lycoming Engines reciprocating engines. This AD requires a crankshaft inspection for certain parts that may be installed. This AD was prompted by the failure of a crankshaft due to incorrect parts installed. We are issuing this AD to prevent engine crankshaft failure and damage to the airplane.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2011/09/14/2011-22244/airworthiness-directives-lycoming-engines-model-io-720-a1b-reciprocating-engines)
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