NTSB Identification: CHI02LA100.
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Accident occurred Sunday, April 07, 2002 in Hastings, MN
Probable Cause Approval Date: 09/30/2003
Aircraft: Piper PA-46-310P, registration: N9184F
Injuries: 4 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 airplane sustained substantial damage during a forced landing on a road after a loss of engine power. The pilot reported he was in cruise flight at 3,000 feet when he noticed a slight surging of the engine and observed fluctuations in the manifold pressure. About 30 seconds to one minute after the surging stopped, the engine power suddenly reduced to no more than idle power and was running very rough. Then the engine lost all power. The pilot executed a forced landing to a paved road, but the airplane veered left off the road and the left wing hit a small tree. The engine inspection revealed the connecting rods for cylinders 3, 4, and 5 were all broken loose from the crankshaft, and these three crank journals showed evidence of extreme heat. The inspection revealed that the number 6 piston had a fatigue fracture across the piston crown structure in line with the piston pin. A hole was burned in the piston near the center of the crown along a fracture line, to the piston interior. The origin of this fracture was the crown surface. No number stamp or defects were observed at the fracture origin site. The inspection of the piston revealed that no material defects or surface anomalies were present at the origin of the larger fatigue crack, and that base metal composition of the piston was consistent with alloy AE109 specification. The engine manufacturer reported that it was in the process of redesigning the piston used in the 310 horsepower TSIO-550-C engines.

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

The engine failure due to oil starvation as a result of the fatigue fracture of the number 6 piston. Additional factors were the unsuitable terrain for landing encountered by the pilot, and the inadequate piston design by the manufacturer.

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