# Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines.
> **Rule** · Final rule, request for comments. · Published 2000-12-14 · Effective 2000-12-29 · 65 FR 78083
## Document
- **Document number:** 00-31537
- **Category:** airworthiness
- **Manufacturer:** Pratt & Whitney PW4000 Series Turbofan
- **Type:** Rule
- **Action:** Final rule, request for comments.
- **Citation:** 65 FR 78083
- **Publication date:** 2000-12-14
- **Effective date:** 2000-12-29
- **FAA docket:** Docket No. 2000-NE-43-AD
## Abstract

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Pratt & Whitney (PW) PW4000 turbofan engines with the current design low pressure turbine (LPT) 4th stage air seal installed. This action requires, based on engine model, replacement of the current design seal with a new design seal, or with a modified seal. This amendment is prompted by reports of cracks in LPT 4th stage air seals. The actions specified by this AD are intended to reduce stresses that could lead to LPT 4th stage air seal cracking, resulting in seal fracture, uncontained engine failure, and damage to the airplane.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2000/12/14/00-31537/airworthiness-directives-pratt-and-whitney-pw4000-series-turbofan-engines)
---
*AI Analytics · CC0 1.0*