AAIB investigation to DG Flugzeugbau DG-1000T, G-CKLY
In-flight separation of a propeller coupling, Court Place Farm Nature Park, Oxfordshire, 26 April 2025
During a local flight, the pilot deployed the engine to gain height to return to the home airfield, when he heard a loud bang. He stowed the engine and after confirming he had control of the aircraft, made a successful landing at Weston-on-the-Green Airfield. An inspection of the aircraft revealed some minor damage to the airframe caused by the propeller when it detached from the engine. The propeller was subsequently recovered from the local area.
The coupling which attached the propeller to the output drive of the engine had separated through a rubber element with one half remaining attached to the engine and the other half attached to the propeller. The investigation determined that the desired surface roughness had not been achieved on the drive-side coupling and this had resulted in an adhesive bond failure between the rubber element of the coupling and the drive-side component. It was concluded that the design of the part and the manufacturing process, had made it challenging to achieve the required surface roughness to effectively bond the rubber to the aluminium. The surface roughness was not identified because of a lack of inspection and acceptance criteria for the surface finish after blasting. The manufacturer has made changes to the coupling to ensure the surface finish is achieved and therefore a more effective bond between the coupling components.
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