1AD/LYC/91 - Crankshaft Removal/Inspection

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Lycoming Piston Engines

AD/LYC/91 Crankshaft Removal/Inspection 10/92 DM

Applicability: All Textron Lycoming piston engines that have been overhauled by or had the crankcase disassembled for major work by Arnhem Aircraft Engineering Pty Ltd under Certificate of Approval No. 4049 during the period 1 January 1990 to 6 August 1992.

Requirement: 1. Remove the crankshaft assembly and dimensionally check the diameters of all bearing journals.

2. Crankshafts with any bearing journal diameter less than the STANDARD dimension listed in the relevant Textron Lycoming Engine Overhaul Manual are to be quarantined and the CAA local Airworthiness District Office notified.

3. Crankshafts with diameters for all bearing journals at the STANDARD dimension listed in the relevant Textron Lycoming Engine Overhaul Manual may be refitted to an engine.

Compliance: For installed engines - Prior to the 31 August 1992.

For uninstalled engines - Before installation into aircraft.

Background: Four crankshaft assemblies repaired by the grinding of bearing journals on behalf of Arnhem Aircraft Engineering Pty Ltd have been found with grinding cracks, two of which failed in flight. Arnhem Aircraft Engineering Pty Ltd has been unable to satisfy the CAA (Australia) as to the location or number of crankshafts repaired by grinding on its behalf.