AD/JT8D/18 Amdt 2 Second Stage Turbine Disc (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/JT8D/18 Amdt 1 and issues the following AD under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Pratt and Whitney Turbine Engines - JT8D Series

AD/JT8D/18 Amdt 2 Second Stage Turbine Disc 7/2005

Applicability:

Pratt and Whitney Aircraft JT8D-15, -17, and -17R turbofan engines.

Requirement:

To prevent possible failure of the second stage turbine disk, inspect second stage turbine disk, Part Numbers 676802, 770602, 780502, 786802, and 787302 details, and Part Numbers 676822, 769722, 769832, 786822, and 787232 assemblies for wear and cracking of the snap diameter and at the bottom of the disk air seal groove, repair the disk, and modify the mating third stage turbine inner air seal in accordance with the requirement of FAA Airworthiness Directive (AD) 85-19-51 R1.

Note:  FAA AD 85-19-51 R1 Amendment 39-5168 refers.

Compliance:

Unless previously accomplished, as per compliance schedule of the FAA AD
85-19-51 R1.

This Amendment becomes effective on 7 July 2005.

Background:

There have been reports of cracking of snap diameter and cracking at the bottom of the disk air seal groove for 2^nd stage turbine disks.  The inspection and repair requirements of this AD are aimed at prevention of 2^nd stage turbine disk failure.

The current amendment deletes reference to the manufacturer’s document and refers to the FAA AD as part of the harmonisation with the engine certificating Authority requirements.

Amendment 1 of this Directive became effective on 26 December 1985.

James Coyne
Delegate of the Civil Aviation Safety Authority

25 May 2005