On November 4, 2012, about 1230 eastern standard time, an experimental Dragonfly-C airplane, N667DF, was substantially damaged when it collided with terrain following a loss of engine power during initial climb from WesMar Aerodrome, a private airstrip located near Darbyville, Ohio. The private pilot was seriously injured. The airplane was registered to and operated by Central Ohio Dragonfly Club, LLC, under the provisions of 14 Code of Federal Regulations Part 91 without a flight plan. Day visual meteorological conditions prevailed for the local area hang glider aero-tow flight that was originating at the time of the accident.

The pilot reported that during initial climb from runway 5 (2,300 feet by 60 feet, grass/turf), about 80 feet above the runway, the airplane experienced a sudden and total loss of engine power while it was in a climbing left turn. He stated that the airplane immediately entered an aerodynamic stall/spin following the loss of engine power. The pilot released the towed hang glider, but he was unable recover from the aerodynamic stall condition before the airplane impacted terrain. The airplane sustained substantial damage to the fuselage and both wings. The pilot reportedly sustained a broken left ankle.A postaccident examination of the two-cylinder Rotax model 582 engine, completed by a Federal Aviation Administration Inspector, revealed excessive piston scoring within one of the cylinder assemblies. Additionally, there was excessive wear observed on the piston wrist-pin. The observed anomalies were consistent with a cold-seizure event, as described in a service training publication provided by the engine manufacturer. The engine manufacturer described a cold-seizure event as a thermo-imbalance condition between the piston and cylinder, which results in insufficient clearance between the piston and the cylinder. Additionally, the engine manufacturer stated that the cylinder thermo-imbalance is typically the result of an insufficient engine warm-up period before takeoff power is applied. The engine, serial number 5742422, had accumulated 205 hours since new.