NTSB Identification: CEN10LA450
14 CFR Part 137: Agricultural
Accident occurred Thursday, July 29, 2010 in Montezuma, IN
Probable Cause Approval Date: 05/21/2012
Aircraft: CESSNA T188C, registration: N2085J
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, while en route to spray a field, the engine lost power and the windshield became obscured with oil. The pilot immediately turned into the wind and made a forced landing into a nearby cornfield. A postaccident examination revealed that the No. 2 connecting rod had separated from the engine crankshaft. Metallurgical examinations found polishing and wear patterns indicative of relative motion between the connecting rod components and an associated rod bolt head/nut. The nut threads were sheared as result of overload failure, consistent with impulse loading. The observed anomalies were consistent with an insufficient fastener preload on installation of the connecting rod bolt. The engine had accumulated 1,193 hours since its last major overhaul. It is likely that the rod bolt head/nut became loose during operation, which led to a failure of the assembly due to impulse loading.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The total loss of engine power due to an insufficient fastener preload that led to the failure of the No. 2 connecting rod assembly. Full narrative available
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