AD/Tay/17 Amdt 1 Low Pressure Turbine Disc Corrosion (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) AD/TAY/17 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.

Rolls Royce Turbine Engines - Tay Series

AD/TAY/17 Amdt 1 Low Pressure Turbine Disc Corrosion 9/2008

Applicability:

Rolls Royce Deutschland Ltd & Co KG TAY 650-15 Engines serial numbers 17249, 17251, 17255, 17256, 17273, 17275, 17280, 17281, 17282, 17300, 17301, 17303, 17327, 17332, 17358, 17365, 17370, 17393, 17425, 17426, 17433, 17437, 17438, 17443, 17445, 17446, 17460, 17470, 17474, 17478, 17490, 17491, 17517, 17518, 17520, 17521, 17522, 17523, 17534, 17539, 17535, 17536, 17538, 17539, 17540, 17541, 17542, 17552, 17553, 17556, 17561, 17562, 17563, 17580, 17581, 17585, 17612, 17613, 17618, 17635, 17637, 17645, 17661, 17686, 17699, 17701, 17702, 17723, 17724, 17736, 17737, 17738, 17739, 17740, 17741, 17742, 17759, 17760, 17807 and 17808 with Module M05300AA (LP Turbine Module) installed.

Note 1:  These engines are known to be installed in Fokker F28 Mark 0100 aircraft.

Requirement:

1.    Inspect the low pressure turbine discs stage 2 and stage 3 for corrosion in accordance with Rolls-Royce Deutschland Non-Modification Alert Service Bulletin TAY-72-A1524, Revision 2 dated 13 June 2008 or later LBA approved revisions.

2.    When, during any of the inspections as required by Requirement 1 of this AD, corrosion is found, replace the affected parts using the rejection criteria described in the Rolls-Royce TAY 650 Engine Manual - E-TAY-3RR, latest revision.

All necessary inspections must be accomplished in accordance with the TAY 650 Engine Manual - E-TAY-3RR, Chapters 72-52-23 and 72-52-24.

Note 2:  EASA AD 2008-0122 dated 1 July 2008 refers.  This AD supersedes EASA AD 20066-0288.

Compliance:

For Requirement 1 - Prior to accumulating 11,700 flight cycles (FC) and thereafter at intervals not exceeding 11,700 FC of the engine.

For Requirement 2 - Before further flight after the effective date of this AD.

This Amendment becomes effective on 28 August 2008.

Background:

Strip results from some of the engines listed in the applicability section of this AD revealed excessively corroded low pressure turbine stage 2 and stage 3 discs.  The corrosion is considered to be caused by the environment in which these engines are operated.

Following a life assessment based on the strip findings, it was determined that inspections for corrosion attack are required.

This amendment extends the applicability to further engine serial numbers.

The original issue of this AD became effective on 23 November 2006.

James Coyne
Delegate of the Civil Aviation Safety Authority

16 July 2008