The pilot reported that, during the agricultural spray run, the engine lost power. The Grumman G164-B was unable to maintain altitude, so the pilot made a forced landing to a rice field near Princeton, California.
After touchdown, the airplane nosed over, which resulted in substantial damage to the rudder.
A post-accident examination of the engine revealed that the No. 2 cylinder head had cracked and lifted under the cooling fins on the cylinder’s left side. The crack continued across the top and inside of the head to the intake valve seat, which would have allowed hot gases to enter the induction system and resulted in the subsequent loss of power.
A review of the airplane’s maintenance records revealed that a mandatory 100-hour repetitive visual inspection of the cylinder had been performed 66.7 flight hours before the accident flight.
Probable cause: The loss of engine power during an agricultural application flight due to a cylinder failure.
NTSB Identification: WPR15LA230
This August 2015 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.