Socata MSTB20, VH-JTI, Bankstown, New South Wales, on 10 October 1989

Circumstances:

The aircraft was being flown on an air test after a previous flight incurred a defect with the emergency gear extension system. The test was conducted in the Bankstown training area and all gear extensions both normal and emergency worked correctly. On return to Bankstown for landing on runway 29 Right the landing gear was lowered on downwind in the circuit and the normal three green indication was noted. The approach and landing was normal until just as the nosewheel touched the runway the right main gear collapsed, and the aircraft skidded to a halt to the right of the centreline. Subsequent investigation revealed the right main gear jury strut pin had separated from the attach bracket on the rear spar. The strut pin retaining circlip had been incorrectly fitted during the last installation.

Significant Factors:

The following factor was considered relevant to the development of the accident:

1. Improper maintenance.

Recommendations:

The jury strut spar bracket P/N TB20.43.013.000 L/H or .001 R/H is supplied as an assembly ex-factory consisting of the bracket and two bushes. Unless the bushes are fully inserted in the bracket the locking characteristics of the circlip on the pin may be compromised. The jury strut pin retaining circlip cannot be inspected in-situ on MSTB20 aircraft. It is therefore recommended that the Civil Aviation Authority consider notification to owners and operators of MSTB20 aircraft that a defect may exist and detail a procedure to check the integrity of the circlip and jury strut pin.