# Proposed AD FAA-2007-29110: Pratt & Whitney PW4090 and PW4090-3 Turbofan Engines

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2009-04-02
- Products: Pratt & Whitney
- Product type: Engine
- Action: Notice of proposed rulemaking (NPRM).
- Published: October 10, 2007, 72 FR 57502
- Comments due: December 10, 2007
- Became: [AD 2009-04-02](https://openairdocs.org/ad/2009-04-02)
- Docket: FAA-2007-29110 (https://www.regulations.gov/docket/FAA-2007-29110, where comments are filed)
- Project: 2007-NE-35-AD
- FR document: E7-19927
- Official PDF: https://openairdocs.org/files/sha256/e1/be/e1be721ef98e97321e13d7135ecf1478ba013c861855b113ed44ac1c36d3b504 (from https://www.govinfo.gov/content/pkg/FR-2007-10-10/pdf/E7-19927.pdf)
- Federal Register: https://www.federalregister.gov/documents/2007/10/10/E7-19927/airworthiness-directives-pratt-and-whitney-pw4090-and-pw4090-3-turbofan-engines
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/2406DAF5CF2416D186257370004986F1.0001
- Page: https://openairdocs.org/proposed/FAA-2007-29110

## Summary

The FAA proposes to adopt a new airworthiness directive (AD) for Pratt & Whitney (PW) PW4090 and PW4090-3 turbofan engines with front turbine hub, part number (P/N) 53L601, installed. This proposed AD would reduce the published life limit of those front turbine hubs from 12,000 cycles-since-new (CSN) to 9,370 CSN. This proposed AD would also remove from service those front turbine hubs using a drawdown schedule. This proposed AD results from PW updating the low-cycle- fatigue (LCF) life analysis for front turbine hubs, P/N 53L601. We are proposing this AD to prevent an uncontained failure of the front turbine hub, resulting in an in-flight engine shutdown and possible damage to the airplane.

## Notices in this docket

- Oct 10, 2007: Notice of proposed rulemaking (NPRM). (first notice), FR document E7-19927, comments due Dec 10, 2007 (https://www.federalregister.gov/documents/2007/10/10/E7-19927/airworthiness-directives-pratt-and-whitney-pw4090-and-pw4090-3-turbofan-engines)

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