# Airworthiness Directives; Rolls-Royce (1971) Limited, Bristol Engine Division Model Viper Mk.601-22 Turbojet Engine
> **Rule** · Final rule; request for comments. · Published 2004-06-22 · Effective 2004-07-07 · 69 FR 34563
## Document
- **Document number:** 04-14051
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 69 FR 34563
- **Publication date:** 2004-06-22
- **Effective date:** 2004-07-07
- **FAA docket:** Docket No. FAA-2004-18024
## Abstract

The FAA is adopting a new airworthiness directive (AD) for Rolls-Royce (1971) Limited, Bristol Engine Division (RR) Model Viper Mk.601-22 turbojet engines. This AD requires reducing the life of certain 1st stage turbine rotor blades from 7,000 hours time-in-service (TIS) to 4,600 hours TIS, and provides a drawdown schedule for blades that have already exceeded the new reduced life limit. This AD results from the manufacturer's investigations into failures of 1st stage turbine rotor blades. We are issuing this AD to prevent multiple failures of 1st stage turbine rotor blades that could result in a dual- engine shutdown.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2004/06/22/04-14051/airworthiness-directives-rolls-royce-1971-limited-bristol-engine-division-model-viper-mk601-22)
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