AD/TPE 331/10 - High Speed Pinion Bearing Assembly - Replacement - CANCELLED

This document cancels a previous aviation safety rule that required specific maintenance on certain aircraft engines.

What it did: The original rule (issued in 1977) required owners and mechanics to replace high-speed pinion bearings in AlliedSignal (Garrett/AiResearch) TPE 331 turbine engines during major overhauls.

What this does: It withdraws that requirement entirely. The bearing replacement is no longer mandatory under this directive.

Who it affects: Aircraft operators and maintenance organisations using TPE 331 series turbine engines.

Why it matters: This removes a compulsory maintenance step, potentially saving time and money for aircraft owners, assuming alternative safety standards now apply.