# Airworthiness Directives; Pratt & Whitney Canada (PWC) PW535A Turboshaft Engines
> **Rule** · Final rule; request for comments. · Published 2006-04-21 · Effective 2006-05-08 · 71 FR 20531
## Document
- **Document number:** 06-3765
- **Category:** airworthiness
- **Manufacturer:** Pratt & Whitney Canada (PWC) PW535A Turboshaft
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 71 FR 20531
- **Publication date:** 2006-04-21
- **Effective date:** 2006-05-08
- **FAA docket:** Docket No. FAA-2006-24117
## Abstract

The FAA is adopting a new airworthiness directive (AD) for Pratt & Whitney Canada (PWC) PW535A turboshaft engines with serial numbers (SNs) lower than DC0241, and with hydromechanical fuel control (HFC) part number (P/N) 819735-4, 819735-5, or 819735-6 installed. This AD requires inspection and verification of the proper adjustment of the ratio unit setscrew adjustment of installed HFC units. This AD results from incidents of PW535A turboshaft engines experiencing lack of response to the power lever input during attempted engine acceleration, due to an incorrect adjustment of the HFC ratio unit setscrew. We are issuing this AD to prevent lack of engine response to power lever input, which could cause a single or dual engine in-flight shutdown event.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2006/04/21/06-3765/airworthiness-directives-pratt-and-whitney-canada-pwc-pw535a-turboshaft-engines)
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