# Proposed AD 94-ANE-54: Pratt & Whitney JT9D Series Turbofan Engines

- Type: Proposed airworthiness directive (not in force)
- Status: Comment period closed
- Action: Notice of proposed rulemaking (NPRM).
- Published: January 11, 1999, 64 FR 1552
- Comments due: March 12, 1999
- Docket: 94-ANE-54
- FR document: 99-492
- Official PDF: https://openairdocs.org/files/sha256/eb/81/eb81d5ddd9de5968c9ee002d45f4517f7349ae443fe7b8f6307297465fc4b379 (from https://www.govinfo.gov/content/pkg/FR-1999-01-11/pdf/99-492.pdf)
- Federal Register: https://www.federalregister.gov/documents/1999/01/11/99-492/airworthiness-directives-pratt-and-whitney-jt9d-series-turbofan-engines
- Page: https://openairdocs.org/proposed/94-ANE-54

## Summary

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to Pratt & Whitney (PW) JT9D series turbofan engines, that currently requires initial and repetitive in-shop or on-wing inspections of the diffuser case rear rail for cracking, and removal, if necessary, of the diffuser case. This action would reduce the allowable crack length, reduce the inspection intervals, and introduce an improved inspection method. This proposal is prompted by a report of an additional diffuser case rupture, and improved understanding of crack propagation rates. The actions specified by the proposed AD are intended to prevent diffuser case rupture, an uncontained engine failure, and damage to the aircraft.

## Notices in this docket

- Jan 11, 1999: Notice of proposed rulemaking (NPRM). (first notice), FR document 99-492, comments due Mar 12, 1999 (https://www.federalregister.gov/documents/1999/01/11/99-492/airworthiness-directives-pratt-and-whitney-jt9d-series-turbofan-engines)

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