Commonwealth legislation

AD/AL 250/33 - Fourth Stage Compressor Wheel - Retirement

RepealedCTH

This Act has been repealed and is no longer in force. It is retained for historical reference.

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Commonwealth

Collection

legislative instrument

Plain English Summary

2/10 complexity

What this does: This is a safety order (called an Airworthiness Directive) that requires owners and operators of specific Allison turbine engines to remove certain faulty compressor wheels from service before they fail.

Who it affects: Anyone operating aircraft with Allison 250-C18 or 250-B15G engines that have compressor wheels with part numbers 6856754 or 6871444 installed.

What must be done: The fourth-stage compressor wheels must be retired (permanently removed from use) within 100 flight hours after 31 May 1979.

Why it matters: Compressor wheels spin at extremely high speeds. If these specific wheels fail in flight, they can shatter and destroy the engine, potentially causing catastrophic damage to the aircraft and endangering lives. This directive forces replacement before fatigue causes failure.

Technical details: Operators must follow the procedures in either Allison document CSL-96 (for C18 engines) or CSL-36 (for B15G engines) to ensure compliance.

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AD/AL 250/33 - Fourth Stage Compressor Wheel - Retirement

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COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

View image in the official source Allison Turbine Engines - 250 Series

AD/AL 250/33 Fourth Stage Compressor Wheel - Retirement 5/79

Applicability: All 250-C18 and 250-B15G series fitted with compressor wheels P/N 6856754 or 6871444.

Document: 1. Allison 250-C18 CSL-96; or

2. Allison B15G TP CSL-36.

Compliance: Within 100 hours’ time in service after 31 May 1979.

Source text

Sourced from the Federal Register of Legislation (legislation.gov.au), CC BY 4.0.