Commonwealth legislation

AD/AL 250/54 Amdt 1 - Engine Turbine Assembly No. 8 Bearing U-Ring Installation

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legislative instrument

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This AD mandates that operators and maintenance organisations for Allison 250‑C28B/C28C engines follow Allison CEB‑A‑72‑2082 Rev 1 for No. 8 bearing U‑ring installation. It aims to stop air leaks into the No. 8 bearing sump that can force oil onto the No. 1 turbine wheel, causing oil fires and first‑stage turbine damage. Practical effect: technical requirements sit in the Revision 1 document and compliance costs, scheduling and execution fall to operators and their maintenance providers.

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AD/AL 250/54 Amdt 1 - Engine Turbine Assembly No. 8 Bearing U-Ring Installation

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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 250/54

Amdt 1

Engine Turbine Assembly No. 8 Bearing U-Ring Installation

5/84

Applicability: Allison 250-C28B/C28C engines.

Document: Allison 250 C28B/C28C CEB-A-72-2082 Rev 1.

Note: FAA AD Allison 83-01-04 AMDT. 39-4539 refers.

Compliance: In accordance with the Requirement Documents.

Background: This have been instances of an air leak occurring into the No. 8 bearing sump, forcing oil through the No. 8 bearing labyrinth seal onto the No. 1 turbine wheel, resulting in oil fires and damage to first stage turbine wheels. This Directive is raised in issue to ensure compliance with Revision 1 of the document which is a complete revision replacing the original.

Source text

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