Commonwealth legislation

AD/AL 250/49 - N2 Overspeed Control System - Disarming

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Commonwealth

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legislative instrument

Plain English Summary

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This airworthiness directive requires disarming the N2 electronic Overspeed Control on Allison 250‑C28B engines, performed in accordance with one of two referenced technical documents, and completed before any flight after 2 March 1982. It applies to owners/operators and maintenance organisations for affected engines and aims to prevent intermittent or spurious N2 overspeed activations that caused in‑flight spooling downs; operators must arrange and fund the required work and accept the resulting downtime.

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AD/AL 250/49 - N2 Overspeed Control System - Disarming

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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 250/49 N2 Overspeed Control System - Disarming 4/82

Applicability: Allison 250-C28B.

Document: 1. Detroit Diesel Allison Commercial Engine Bulletin 250-C28B CEB-A-73-2020; or

FAA AD 82-03-02 Detroit Diesel Allison Amendment 39-4305. Compliance: Before further flight after 2 March 1982.

Background: Overseas, there have been 5 reported spooling downs of Allison 250-C28B engines in flight which were attributed to intermittent and spurious activation of the N2 (Electronic) Overspeed Control System. This Directive is issued in order to preclude further such intermittent or spurious power reductions or shut-downs.

Source text

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