NTSB Identification: WPR10LA396
14 CFR Part 137: Agricultural
Accident occurred Wednesday, August 11, 2010 in Tracy, CA
Probable Cause Approval Date: 08/29/2012
Aircraft: GRUMMAN G164, registration: N6781K
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.

During an aerial application flight, the pilot heard a loud bang, which was followed by a loss of engine power and shaking. During the forced landing to a wet field, the pilot activated the left brake to intentionally ground-loop the airplane; however, it did not respond. The airplane continued its forward movement until it struck a fence at the end of the field and came to rest inverted. During the postaccident engine examination, it was discovered that the connecting links for all but the No. 7 cylinder were broken and the master rod was sheared. Due to the extent of internal damage, it could not be determined if the master rod or the connecting link had failed first.

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

A total loss of engine power while maneuvering due to an internal catastrophic failure to the master rod and piston connecting rod links.

Full narrative available

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