# Proposed AD FAA-2014-0521: CFM International S.A. Turbofan Engines

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2015-04-02
- Products: CFM International
- Product type: Engine
- Action: Notice of proposed rulemaking (NPRM).
- Published: October 2, 2014, 79 FR 59467
- Comments due: December 1, 2014
- Became: [AD 2015-04-02](https://openairdocs.org/ad/2015-04-02)
- Docket: FAA-2014-0521 (https://www.regulations.gov/docket/FAA-2014-0521, where comments are filed)
- Project: 2014-NE-11-AD
- FR document: 2014-23563
- Official PDF: https://openairdocs.org/files/sha256/e3/a1/e3a1ccf49eed1465735b6ddc769c40978d3f0d4896ed6f384f112f8f38702a67 (from https://www.govinfo.gov/content/pkg/FR-2014-10-02/pdf/2014-23563.pdf)
- Federal Register: https://www.federalregister.gov/documents/2014/10/02/2014-23563/airworthiness-directives-cfm-international-sa-turbofan-engines
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/58D6BA02FA7949F086257D65004D6652.0001
- Page: https://openairdocs.org/proposed/FAA-2014-0521

## Summary

We propose to adopt a new airworthiness directive (AD) for all CFM International (CFM) S.A. CFM56-7B series turbofan engines. This proposed AD was prompted by a dual engine thrust instability event that resulted in the overspeed and in-flight shutdown (IFSD) of one engine. This proposed AD would require modification of the engine by removing full authority digital engine control (FADEC) software, version 7BV4 or earlier, installed in the electronic engine controls (EECs) on CFM56-7B engines. We are proposing this AD to prevent a thrust instability event, which could lead to overspeed and IFSD of one or more engines, loss of thrust control, damage to the engine, and damage to the airplane.

## Notices in this docket

- Oct 2, 2014: Notice of proposed rulemaking (NPRM). (first notice), FR document 2014-23563, comments due Dec 1, 2014 (https://www.federalregister.gov/documents/2014/10/02/2014-23563/airworthiness-directives-cfm-international-sa-turbofan-engines)

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