Accident Sequence
According to the pilot, during the three weeks prior to the accident, he had averaged 15-hour work days. On the day of the accident, the pilot's first flight, a ferry flight to the airstrip, began at 0600. At 0722, he started the aerial application flights. At 1203, the airplane returned from the 20th application flight and was refueled.
Pilot Actions
During the refueling, the pilot retracted the flaps to improve the footing of the person fueling the left main fuel tank. The pilot stated that he did not extend the flaps before the 21st takeoff and did not use a checklist. After takeoff, the pilot reported that the airplane would not climb. The airplane impacted trees during the initial climb after takeoff.
The airplane flight manual requires that flaps be extended 10 degrees before takeoff with a full hopper load or from a short runway.
Maintenance Findings
Examination of the flap actuator jack screw and ball nut assembly revealed that the ball nut was within 1/4 inch of the large gear-box ball bearing on the jack screw. This finding is consistent with the flaps being in the retracted position.