Amateur-built KOLB MARK III N9144E accident near Versailles, Missouri

Probable cause

A loss of engine power due to adjustments and modifications that the pilot made to the engine and airplane.

NTSB analysis

The pilot stated that the accident occurred on his sixth flight in the airplane. The engine run-up for the accident flight was normal, and just after takeoff, the engine over-temperature warning light illuminated. He banked the airplane to return to the airstrip. He said he decreased the engine power to keep the temperatures down but then had to increase engine power and pitch in order to clear trees along the flight path. The engine subsequently stopped producing power. The landing gear was ripped off during the forced landing in a field and the pilot was dragged across the terrain while still in the sling-type seat, which resulted in the pilot sustaining serious back injuries.

After purchasing the airplane, the pilot installed a new engine, a ballistic recovery chute, a new fuel tank, and new fuel lines. However, he stated that he had continuing problems with high engine temperatures and a high static engine rpm. In response to these problems, the pilot replaced the static jets in both carburetors, tuned and synchronized both carburetors, and replaced the heat probes. He also installed an engine information system.

A postaccident examination of the engine and airplane revealed that both carburetors were not adjusted properly, thus restricting fuel flow; improper fuel jets were installed, which produced a richer fuel/air mixture; and the coolant water temperature probe was in the wrong location, which would have prevented accurate temperature sensing. In addition, the positions of the air deflectors, the ballistic recovery chute, and the oil injection reservoir may have affected the amount of cooling air to the engine. No evidence of internal damage was noted to the pistons and cylinders. The engine demonstrated the ability to run normally during postaccident testing. Although the exact cause of the loss of engine power was not determined, it is likely that a combination of the modifications that were made to the airplane and engine that resulted in the loss of engine power.

Text from the NTSB. Open the NTSB docket for CEN12LA008 for the full record.