AD/AL 250/62 Amdt 1 Fourth Stage Nozzle Assembly 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 250/62 Amdt 1.

Allison Turbine Engines - 250 Series

AD/AL 250/62 Amdt 1 Fourth Stage Nozzle Assembly - Replacement 6/2009

Requirement:

CANCELLED.

This AD is cancelled on 4 June 2009.

Background:

This unique Australian AD raised in 1985 against Allison Commercial Engine Bulletin (CEB) 250-C30 CEB-A-72-3122 Rev.1 required a modification by machining the inner band area of the fourth stage turbine nozzle to provide increased clearance with the rim of the third stage turbine wheel to prevent rubbing contact between the third stage turbine wheel and the inner band of the fourth stage nozzle.

Compliance was:  Prior to completion of the next overhaul after 31 December 1984 or on the next occasion the power turbine is disassembled.

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