AAIB investigation to Kolb Twinstar Mk III Xtra, G-CGZA

Loss of propeller in flight, Swinefleet common, 4 June 2015.


The propeller separated from the engine in flight, without warning and damaged the tail boom. The pilot was able to carry out an emergency landing without incident. The propeller was not recovered, but photographs taken of the fracture faces of the propeller retaining bolt shanks, which had remained attached to the engine crankshaft, showed clear evidence of failure due to the presence of high cycle fatigue. As a result if this incident, and two similar events , the Light Aircraft Association (LAA) have confirmed that they are in discussion with the engine manufacturer regarding the issue. Additionally details of the event, together with the recommended procedures for propeller attachment, have been published in the July edition of the LAA’s engineering “Safety Spot”.

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Kolb Twinstar Mk III Xtra, G-CGZA 09-15

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Glossary of abbreviations

Published 10 September 2015