2000 Glaser-Dirks DG-400 accident near Jesenwang

Incident Overview and Flight Details On 11 August 2000, a self-launching Glaser-Dirks DG-400 motor glider departed from the traffic landing site at Jesenwang (EDMJ) for a private flight. During the initial climb, the pilot experienced severe vibration and reduced the engine to idle. The aircraft was subsequently landed in a cornfield approximately 2.4 km northwest of the airfield. The pilot was unharmed, and the aircraft sustained minor damage. ## Technical Investigation and Findings The German Federal Aviation Accident Investigation Office (BFU) determined that the rear support plate of the propeller arm had fractured. Metallographic analysis revealed that the failure was caused by fatigue cracks originating near the washer imprints. The investigation attributed the stress concentrations to a stiffness jump at the washer edge and the pre-tension of the connecting bolt, combined with alignment errors. ## Safety Recommendations The BFU recommended that the manufacturer of the DG-400 use or fabricate connection elements that provide a more secure and vibration-tolerant connection between the propeller arm and the engine. All DG-400 motor gliders with auxiliary engines should be retrofitted with these improved components.