NTSB Identification: FTW97LA189.
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Accident occurred Saturday, May 10, 1997 in GREELEY, CO
Probable Cause Approval Date: 01/07/1998
Aircraft: Townsend KITFOX, registration: N950AW
Injuries: 1 Uninjured.

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 pilot was test flying his experimental airplane in the local area when the engine lost partial power then seized. The airplane landed hard, shearing off the right main landing gear and buckling the fuselage. Post accident disassembly of the engine revealed evidence of high heat distress and a lack of lubrication. The builder said he had adjusted the fuel-oil metering system on previous occasions because the engine was difficult to start and operated erratically. Operating temperatures were also high. The engine was further examined by an independent repair facility. They found that the engine did not have a harmonic balancer, which allowed the crankshaft bearings on the magneto end to move within the crankcase. Extreme internal heat build up and oil starvation damaged the crankshaft bearings, rotary valve, disk, and gear, and caused the connecting rod to eventually fail.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The engine manufacturer's inadequate quality control by failing to install the harmonic balancer, causing the engine to fail catastrophically. A factor was the lack of suitable terrain on which to make a forced landing.

Full narrative available

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