AD/F100/75 Amdt 1 High Pressure Compressor (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/F100/75 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.

Fokker F100 (F28 Mk 100) Series Aeroplanes

AD/F100/75 Amdt 1 High Pressure Compressor 6/2006

Applicability:

Fokker Aircraft B.V. Model F28 Mark 0070 and Mark 0100 aircraft, all serial numbers, if equipped with Rolls-Royce (Deutschland) Tay620 or Tay650 series engines in pre-SB TAY-72-1653 configuration.

Requirement:

1.    Incorporate the minimum vane tip clearance modification in accordance with Rolls-Royce Deutschland (RRD) Service Bulletin (SB) TAY-72-1653 dated
29 August 2005 or a later EASA approved revision.

2.    No aeroplane shall be operated unless at least one engine is modified in accordance with RRD SB TAY-72-1653.

3.    No aeroplane shall be operated unless both engines are modified in accordance with RRD SB TAY-72-1653.

Note:  Civil Aviation Authority Netherlands Airworthiness Directive Nr.
NL-2005-014R1 EASA Approval No. 2006-017 dated 20 January 2006 refers.

Compliance:

1.    At the next scheduled or unscheduled shop visit of each affected engine for which the High-Pressure Compressor Section (Module 3) is disassembled.

2.    After 1 January 2011.

3.    After 1 January 2015.

This Amendment becomes effective on 8 June 2006.

Background:

Between 1991 and the end of 2004, 39 Rolls-Royce Tay engines have experienced heavy rubbing between the High Pressure Compressor (HPC) stator vane tips and the corresponding HPC rotor spacer, causing partial loss of HPC rotor spacer material.  Investigation revealed that HPC spacer rubbing occurs due to thermal and aircraft manoeuvre induced closure of the vane tip-to-spacer gap on engines where the gap was close to the minimum vane tip clearance that is applicable during engine build-up.  Nine of the referenced events resulted in a commanded In-Flight Shut-Down (IFSD).  There are also indications that some of these events resulted in partial or total loss of thrust control (LOTC), due to engine stall/stagnation and/or high Turbine Gas Temperature (TGT).  This condition, if not corrected, may cause further events of spacer material loss, potentially reducing the surge margin and resulting in HPC surge events and subsequently to LOTC or IFSD.  This AD requires a modification (increase) of the minimum vane tip clearances between the HPC stage 4 through 11 stator vane tips and the corresponding HPC rotor spacers on all Tay620 and Tay650 series engines.

This revision is made to allow a period of operation with only a single engine per aircraft modified as required and to delay the final compliance date for both engines to be modified.

The original issue of this Airworthiness Directive became effective 16 March 2006.

James Coyne
Delegate of the Civil Aviation Safety Authority

28 April 2006