NTSB Identification: WPR09LA077
14 CFR Part 91: General Aviation
Accident occurred Friday, January 09, 2009 in Fremont, CA
Probable Cause Approval Date: 03/03/2010
Aircraft: CESSNA R172K, registration: N758FN
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 reported that after takeoff, and during a left turn, he heard a sudden change in the engine sound followed by a loss of power. He stated that he increased and decreased the throttle with little response from the engine and elected to make a precautionary landing onto a nearby levy. During the landing roll on the levy, the airplane veered to the right, exited the levy, and nosed over in a bog. Both wings sustained substantial damage. Examination of the engine revealed that the oil pump/tachometer drive gear separated from the base of its driveshaft. Metallurgical examination revealed that the oil pump drive gear failed at the intersection of the shaft and gear. Scanning electron microscope images of the fracture showed raised and flattened areas typical of contact damage during cyclic loading. The cause of the fracture was not determined.

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

The partial loss of engine power during takeoff due to an oil pump/tachometer drive gear failure for undetermined reasons.

Full narrative available

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