# Proposed AD 99-NE-57-AD: CFM International CFM56-2, -2A, 2B, -3, -3B, and -3C Series Turbofan Engines

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2000-05-22
- Action: Notice of proposed rulemaking (NPRM).
- Published: December 13, 1999, 64 FR 69428
- Comments due: January 12, 2000
- Became: [AD 2000-05-22](https://openairdocs.org/ad/2000-05-22)
- Docket: 99-NE-57-AD
- FR document: 99-32194
- Official PDF: https://openairdocs.org/files/sha256/b7/55/b75590e9124df7271d8aafd0f7b925e8393862696009586a04c554f66eee8fc0 (from https://www.govinfo.gov/content/pkg/FR-1999-12-13/pdf/99-32194.pdf)
- Federal Register: https://www.federalregister.gov/documents/1999/12/13/99-32194/airworthiness-directives-cfm-international-cfm56-2--2a-2b--3--3b-and--3c-series-turbofan-engines
- Page: https://openairdocs.org/proposed/99-NE-57-AD

## Summary

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to CFM International CFM56-2, -2A, - 2B, -3, -3B, and -3C series turbofan engines. This proposal would require a one-time eddy current inspection (ECI) for cracks in the bolt holes of high pressure turbine (HPT) front rotating air seals. This proposal is prompted by reports of machining anomalies in a bolt hole that led to an HPT front rotating air seal failure. The actions specified by the proposed AD are intended to detect cracks in the bolt holes of HPT front rotating air seals, which can lead to an uncontained engine failure and damage to the aircraft.

## Notices in this docket

- Dec 13, 1999: Notice of proposed rulemaking (NPRM). (first notice), FR document 99-32194, comments due Jan 12, 2000 (https://www.federalregister.gov/documents/1999/12/13/99-32194/airworthiness-directives-cfm-international-cfm56-2--2a-2b--3--3b-and--3c-series-turbofan-engines)

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