1AD/TFE 731/25 - Low Pressure Turbine Nozzle A5 Airseal

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE731 Series

AD/TFE731/25 Low Pressure Turbine Nozzle A5 Airseal 11/94 DM

Applicability: TFE731-3 series engines not incorporating Allied Signal Service Bulletin TFE731- 72-3502 or TFE731-72-3509 as applicable.

Requirement: Replace the low pressure turbine nozzle A5 airseal in accordance with Allied Signal Service Bulletin TFE731-72-3502 or TFE731-72-3509 as applicable.

Note: This Directive provides the terminating action for CAO105 Airworthiness Directives, AD/HS125/130 Amdt 1, AD/IAI-W/16 Amdt 1 and AD/CESSNA 650/5.

Compliance: Effective 14 September 1994:

Airseals with less than 500 hours total time in service since new; prior to accumulating 650 hours total time in service.

Airseals with more than 500 hours total time in service since new; within 150 hours time in service.

Background: This Directive has been issued to require replacement of certain low pressure turbine nozzle A5 airseals. The requirement follows reports of uncontained 1st stage low pressure turbine disc failures in AlliedSignal TFE731-3 engines.

The turbine disc failures were attributed to failure of the A5 airseal.