NTSB Identification: ERA12LA071
14 CFR Part 91: General Aviation
Accident occurred Saturday, November 05, 2011 in Okeechobee, FL
Probable Cause Approval Date: 02/27/2013
Aircraft: SIAI-MARCHETTI S205-22R, registration: N729WA
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.

According to the pilot, during climbout, the engine lost partial power and was running rough. The pilot was unable to restore the engine to full power and made a forced landing in a river. Examination and partial disassembly of the engine revealed that the alternator drive adaptor did not function, the alternator drive gear exhibited extensive wear, and the gear teeth were smeared. The alternator drive bearings were not present, and metal particles were found throughout the oil system in the engine. In addition, the engine alternator drive belt that was driven by the engine was not located and the alternator adjustment was on the maximum setting. According to the engine maintenance log, the alternator was replaced by the pilot/owner and was signed off by an airframe and powerplant mechanic. The airplane had accumulated 2 hours of flight time since the alternator was replaced by the pilot/owner. It is likely that the added pressure to the crankshaft from the alternator drive shaft and the metal in the engine resulted in the engine losing partial power.

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

A partial loss of engine power due to a failure of the drive bearings in the alternator drive system. Contributing to the accident was the inadequate maintenance.

Full narrative available

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