Accident Sequence
The pilot departed from runway 35 at Smith Center Municipal Airport. After turning east and retracting flaps, the tail of the aircraft sank. The pilot reported poor flying characteristics, describing the airplane as if it were on the verge of a stall. With the throttle and mixture at full forward, the tachometer indicated 2,700 rpm. Re-extending the flaps improved performance. Despite the issues, the pilot continued to a field for agricultural spraying, believing that offloading some of the chemical weight would improve handling.
The pilot climbed to approximately 300 feet above ground level (agl) while approaching the pasture. After circling to inspect for obstacles, the pilot initiated a spraying pass about 20 feet agl. Following the pass, a wide right turn was executed; the airplane could not maintain altitude. The pilot attributed this to the aircraft's weight and proceeded with a second pass, followed by a left turn toward the southwest and the airport. Upon completing the turn, the airplane had descended to roughly 40 feet agl. The pilot observed power lines ahead that were now above his altitude. Beginning a climb about three-quarters of a mile from the power lines, the airplane stalled at approximately 40 feet agl. The pilot leveled the wings and prepared for impact. The aircraft struck the ground in a flat attitude, sliding approximately 100 feet before hitting a pasture fence.
Aircraft Examination
An examination of the airplane revealed no anomalies. The density altitude at the time of the accident was calculated as 2,489 feet. The gross weight was determined to be approximately 2,993 pounds. For reference, specifications for a PA-25-235 indicate an empty weight of 1,288 pounds and a maximum takeoff weight of 2,900 pounds. Civil Aeronautics Manual (CAM) 8, paragraph 8.10-4 (b) "Maximum Weight" notes that establishing a maximum weight for an agricultural aircraft is not required.