1AD/AL 250/80 Amdt 1 - Gearbox - Torquemeter Gearshaft Assembly

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AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/AL250/80 and issues the following AD under subregulation 39.1 (1) of CAR 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.

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Allison Turbine Engines - 250 Series

AD/AL 250/80

Amdt 1

Gearbox - Torquemeter Gearshaft Assembly 8/2002

Applicability: All 250-C20, -C20R, - B17 and B17F Series II engines with less than 100 hours’ time in service since the installation of one of the following part number (P/N) helical torquemeter gearshaft assemblies.

23035299, 23038191, 6889701, 6871218, 6870941, 23030857, 23004504, 23037441.

Note 1: This Directive is only applicable to engines which have had maintenance carried out on the gearbox in the last 100 hours engine time in service and had one of the above part number gearshafts installed with less than 100 hours’ time since new during that maintenance.

Requirement: Remove applicable helical torquemeter gearshaft assemblies from service in accordance with one of the following Rolls Royce Alert Commercial Engine Bulletins as applicable by engine model; CEB A-1386R1, CEB A-72-4087R1, TP CEB A- 1331R1, TP CEB A-72-2083R1.

Compliance with the previous issue of these Bulletins satisfies the requirements of this Directive.

Note 2: FAA AD 2001-24-12 refers.

Compliance: Unless previously accomplished, effective 8 August 2002; before further flight.

This amendment becomes effective on 8 August 2002.

Background: This Directive has been amended to reflect FAA AD 2001-24-12. Rolls Royce Alert Commercial Engine Bulletins CEB A-1386R1, CEB A-72-4087R1, TP CEB A- 1331R1, TP CEB A-72-2083R1 have been revised to reflect additional data. The original Directive was issued to address a reported power turbine overspeed that resulted in an uncontained release of turbine blades and turbine disc fragments. The overspeed release resulted in an engine fire and damage to the aircraft. The overspeed resulted from a high cycle fatigue initiated failure of the helical Torquemeter gearshaft. The examination of the failed gearshaft revealed evidence of a pre-existing crack.