NTSB Identification: CHI04CA261.
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Accident occurred Saturday, September 18, 2004 in Pontiac, MI
Probable Cause Approval Date: 12/03/2004
Aircraft: Abbott RAF 2000, registration: N702BX
Injuries: 1 Uninjured.

NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.

The amateur-built gyrocopter sustained substantial damage during a forced landing after takeoff. Prior to takeoff, the pilot had performed a 30-40 minute ground run to check the engine cooling system that had been modified prior to the flight. The pilot reported that the engine operating temperature during the ground run was 140 degrees F and there were no coolant leaks. The pilot reported that during the takeoff, the gyrocopter's climb performance was not as good as he had anticipated. By the end of runway, the gyrocopter had climbed to about 200 feet above ground level (agl), and the engine started to lose power. The pilot declared an emergency and attempted to return to the runway. The pilot reported that the gyrocopter "did not have enough altitude or speed to make a proper landing." The pilot landed the gyrocopter in a grassy area at the end of the runway. A visual inspection of the cylinders with a borescope revealed that both aft cylinders exhibited evidence of scoring and overheating. The gyrocopter pilot/owner had altered the engine cooling system by moving the radiator approximately four inches aft of its original location, because the engine operating temperature was higher than normal (190-200 degrees F). By moving the radiator aft, it moved the radiator further away from the engine exhaust system, and it provided for increased cooling system fluid capacity by lengthening the radiator hoses. The pilot/owner was unable to return all the coolant that he had drained from the radiator prior to the modification, back into the radiator after the modification was made. The cooling system modification was made at the advice of the airframe kit manufacturer, however, the pilot/owner was not a mechanic and he did not have the required cooling system service instructions available at the time the modification was made.

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

The partial loss of engine power due to the scoring and overheating of the cylinders as a result of the pilot/owner's improper servicing of the modified engine cooling system. Additional factors included the pilot/owner modifying and servicing the engine cooling system without maintenance instructions available for reference.

Full narrative available

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