Ad/Al 250/47 - First Stage Turbine Wheel P/N 6853306 - Replacement - 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 250/47.

Allison Turbine Engines - 250 Series

AD/AL 250/47 First Stage Turbine Wheel
P/N 6853306 - Replacement 10/2009

Requirement:

CANCELLED.

This AD is cancelled on 24 September 2009.

Background:

This unique Australian AD raised in 1981 against Allison Commercial Engine Bulletin (CEB) 250-C120 CEB-1048 and 250-B17 TP CEB-1031 required installation of improved 1st stage turbine wheel and 1st and 2nd stage nozzles following manufacturer report of 1st stage turbine wheel failures.

Compliance was:  As per reference document.

Revision 3 of the requirement document reclassified distribution from "overhaul" to "maintenance" and amended "Compliance" to a mandatory time-in-service or calendar time limit.  As legislation now requires replacement of time-lifed components this AD is considered to be no longer required.

James Coyne
Delegate of the Civil Aviation Safety Authority

14 August 2009