NTSB Identification: CEN13LA055
14 CFR Part 91: General Aviation
Accident occurred Sunday, November 04, 2012 in Darbyville, OH
Probable Cause Approval Date: 09/30/2014
Aircraft: CENTRAL OHIO DRAGONFLY CLUB DRAGONFLY-C, registration: N667DF
Injuries: 1 Serious.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The accident occurred during an aero-tow of a hang glider. The pilot reported that during initial climb, 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. A postaccident examination of the two-cylinder engine revealed excessive piston scoring within one of the cylinder assemblies and excessive wear on the piston wrist-pin. The observed anomalies were consistent with a cold-seizure event. A cold-seizure event is a thermo-imbalance condition between the piston and cylinder, which results in an insufficient clearance between the piston and the cylinder. The cylinder thermo-imbalance condition is typically the result of an insufficient engine warm-up period before takeoff power is applied. However, the conditions that led to the cold-seizure event may not have been limited to the accident flight. The total loss of engine power during initial climb, while towing a hang glider, likely contributed to the aerodynamic stall/spin encountered at a low altitude. Additionally, the low altitude at which the aerodynamic stall/spin was encountered was likely insufficient to have allowed a recovery before the airplane impacted terrain.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The total loss of engine power due to a cold-seizure event that occurred at a low altitude, which precluded the pilot's recovery from an inadvertent aerodynamic stall/spin. Full narrative available
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