# Proposed AD FAA-2007-0419: General Electric Company CF34-1A, -3A, -3A1, -3A2, -3B, and -3B1 Turbofan Engines

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2009-07-12
- Products: General Electric
- Product type: Engine
- Action: Notice of proposed rulemaking (NPRM).
- Published: July 23, 2008, 73 FR 42725
- Comments due: September 22, 2008
- Became: [AD 2009-07-12](https://openairdocs.org/ad/2009-07-12)
- Docket: FAA-2007-0419 (https://www.regulations.gov/docket/FAA-2007-0419, where comments are filed)
- Project: 2007-NE-52-AD
- FR document: E8-16884
- Official PDF: https://openairdocs.org/files/sha256/cf/fe/cffee53c71606459b587336a905a1550eeee89d6795ed1b2e87d421c703d3742 (from https://www.govinfo.gov/content/pkg/FR-2008-07-23/pdf/E8-16884.pdf)
- Federal Register: https://www.federalregister.gov/documents/2008/07/23/E8-16884/airworthiness-directives-general-electric-company-cf34-1a--3a--3a1--3a2--3b-and--3b1-turbofan
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/39EFDB553E92E89F8625748F0051ED5A.0001
- Page: https://openairdocs.org/proposed/FAA-2007-0419

## Summary

The FAA proposes to adopt a new airworthiness directive (AD) for General Electric Company (GE) CF34-1A, -3A, -3A1, -3A2, -3B, and - 3B1 turbofan engines with high-pressure (HP) rotor 4-step air balance piston stationary seals (4-step seals), part numbers 4923T54G01, 6019T90G03, 6037T99G01, 6037T99G02, and 6037T99G03, installed. This proposed AD would require removing the 4-step seals and incorporating an 8-step seal at the next piece-part exposure. This proposed AD results from the investigation of an airplane accident. Both engines experienced high- altitude flameouts. Rotation of the HP rotors was not maintained during descent and the engines could not be restarted. We are proposing this AD to prevent the inability to restart both engines after flameout due to excessive friction of the 4-step seal, which could result in subsequent forced landing of the airplane.

## Notices in this docket

- Jul 23, 2008: Notice of proposed rulemaking (NPRM). (first notice), FR document E8-16884, comments due Sep 22, 2008 (https://www.federalregister.gov/documents/2008/07/23/E8-16884/airworthiness-directives-general-electric-company-cf34-1a--3a--3a1--3a2--3b-and--3b1-turbofan)

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