# Proposed AD FAA-2007-27230: Pratt & Whitney (PW) PW4164, PW4168, and PW4168A Turbofan Engines

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2007-26-20
- Products: Pratt & Whitney
- Product type: Engine
- Action: Notice of proposed rulemaking (NPRM).
- Published: May 21, 2007, 72 FR 28459
- Comments due: July 20, 2007
- Became: [AD 2007-26-20](https://openairdocs.org/ad/2007-26-20)
- Docket: FAA-2007-27230 (https://www.regulations.gov/docket/FAA-2007-27230, where comments are filed)
- Project: 2007-NE-04-AD
- FR document: E7-9697
- Official PDF: https://openairdocs.org/files/sha256/a0/3d/a03d4d889d9cada696f48cac4f37d11e02cacd2a37d3856fdb7ffbd8a976eb15 (from https://www.govinfo.gov/content/pkg/FR-2007-05-21/pdf/E7-9697.pdf)
- Federal Register: https://www.federalregister.gov/documents/2007/05/21/E7-9697/airworthiness-directives-pratt-and-whitney-pw-pw4164-pw4168-and-pw4168a-turbofan-engines
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/5FCB7CACB0DC146D862572E2004986E2.0001
- Page: https://openairdocs.org/proposed/FAA-2007-27230

## Summary

The FAA proposes to adopt a new airworthiness directive (AD) for PW PW4164, PW4168, and PW4168A turbofan engines with certain low pressure turbine (LPT) stage 4 disks, part number (P/N) 51N404, installed. This proposed AD would require removing certain LPT stage 4 disks, listed by serial number at the next piece-part exposure or within 7,500 cycles-since-new (CSN), whichever occurs first. This proposed AD results from a report of improperly manufactured LPT stage 4 disks. We are proposing this AD to prevent an uncontained engine failure due to low-cycle fatigue (LCF), which could result in damage to the airplane.

## Notices in this docket

- May 21, 2007: Notice of proposed rulemaking (NPRM). (first notice), FR document E7-9697, comments due Jul 20, 2007 (https://www.federalregister.gov/documents/2007/05/21/E7-9697/airworthiness-directives-pratt-and-whitney-pw-pw4164-pw4168-and-pw4168a-turbofan-engines)

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