Probable cause
A total loss of engine power while maneuvering due to an internal catastrophic failure to the master rod and piston connecting rod links.
NTSB analysis
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.
Text from the NTSB. Open the NTSB docket for WPR10LA396 for the full record.
Event
- Date
- Aug 11, 2010
- Type
- Accident
- Place
- Tracy, California
- Nearest airport
- Private Airstrip
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Grumman G164
- N-number
- N6781K
- Category
- Airplane
- Damage
- Substantial
- Operating rule
- Part 137 (agricultural)
- Purpose of flight
- Aerial application
Other records under this N-number
From the NTSB aviation accident database: N-registered aircraft, events since 2008, data through Oct 28, 2026. The file is published monthly, so the latest weeks are incomplete and recent records can change. The official source is the NTSB aviation investigation search. CheckAero is independent and not affiliated with the NTSB.