AD/TPE 331/11 - High Speed Pinion Bearing Assembly - Replacement - CANCELLED

What this is: An Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) that cancels an earlier safety rule affecting certain aircraft turbine engines.

What it does: This document officially scraps a previous directive (AD/TPE 331/11) that required aircraft operators to replace high-speed pinion bearing assemblies in AlliedSignal (Garrett/AiResearch) TPE 331 series turbine engines. The old rule mandated that specific maintenance actions (following Airesearch Service Bulletin No. 659) had to be completed before installing these engines in aircraft following major re-conditioning work performed after May 1972.

Who it affects: Aircraft operators, maintenance organisations, and engineers who work with TPE 331 turbine engines.

Why it matters: The safety risk that originally justified the bearing replacement requirement no longer exists, so CASA has removed the obligation. Operators no longer need to comply with the previous directive.