Amateur-built CHALLENGER II N12911 accident near Neshkoro, Wisconsin

Probable cause

The total loss of engine power during the initial climb due to a cold seizure as a result of a broken fan V-belt. Contributing to the accident was the passenger's interference with the flight controls during the forced landing.

NTSB analysis

Prior to the local flight, the pilot, who was seated in the rear seat, completed a preflight check and engine run-up. During the initial climb, at 1,200 feet above ground level, the engine lost total power and the pilot initiated a forced landing to a private grass airstrip. While maneuvering the airplane for the forced landing, the pilot felt his left rudder pedal pressed to the floor. The pilot thought that the passenger may have been frightened and stepped on the rudder pedal. The pilot instructed to the passenger to release the rudder pedal as the airplane entered into a slip and was losing altitude; however, the passenger did not respond to the pilot. Due to the loss of altitude, the airplane was unable to reach the airstrip and impacted trees. A postaccident examination of the engine revealed that the cooling fan V-belt was broken and that the pistons exhibited scoring signatures consistent with a cold seizure. According to the manufacturer, the engine is susceptible to cold seizures when there is inadequate cooling of the cylinders, such as with a broken cooling fan V-belt. Review of the engine manufacturer’s installation and operations manual revealed warnings that "the engine by design is subject to sudden stoppage," and that it does not conform to aircraft standards.

Text from the NTSB. Open the NTSB docket for CEN11FA433 for the full record.