AD/AL 250/69 Installation of Internal Energy Absorbing Ring Cancelled (Cth)

AIRWORTHINESS DIRECTIVE

On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive AD/AL 250/69.

Allison Turbine Engines - 250 Series

AD/AL 250/69 Installation of Internal Energy Absorbing Ring 6/2009

Requirement:

CANCELLED.

This AD is cancelled on 4 June 2009.

Background:

This unique Australian AD raised in 1986 against  Allison Commercial Engine Bulletin (CEB) 250-C28 CEB-A-72-2126 required a modification to the engine gas producer support and second stage nozzle to allow for installation of an internal energy absorbing ring followed by installation of an internal energy absorbing ring in the plane of the number one turbine wheel.  This requirement was to preclude the possibility of damage in the event of a first stage turbine wheel burst.

Compliance was:  In accordance with the requirement document.  The requirement document compliance was:

1.    Model 250-C28 series engines installed in twin engined helicopters, accomplish at time of next gas producer rotor disassembly, but no later than 30 May 1986.

2.    Model 250-C28 series engines installed in single engined helicopters, accomplish at time of next gas producer rotor disassembly, but no later than 30 November 1987.

This AD has been sufficiently promulgated for the affected engines to have been modified by now; therefore this AD is considered to be no longer required.

James Coyne
Delegate of the Civil Aviation Safety Authority

24 April 2009