Schweizer G-164B N3633B accident near Alturas, California

Probable cause

A total loss of engine power due to fuel starvation, which resulted from a fuel system contamination and a clogged fuel filter. Contributing to the accident was the rough terrain.

NTSB analysis

The pilot reported that while maneuvering during an agricultural spray flight he felt the turbine engine shudder, and then it continued to operate normally. As a precaution, the pilot discontinued dispensing fertilizer and turned the heavily loaded airplane toward the departure airstrip. Suddenly, the engine shuddered again, and the pilot opted to immediately land in a nearby pasture. All engine power was lost as the airplane approached the field. The pilot made a forced landing on the rough ground and the airplane nosed over during rollout. The operator reported that inspection of the airplane's fuel filter revealed debris or some kind of organism that clogged the fuel filter. The same contaminating material was found in the airplane's fuel tanks. The operator also reported that the airplane had been refueled from a tank truck that was from out of the area.

Text from the NTSB. Open the NTSB docket for LAX08CA228 for the full record.