Circumstances
The pilot attempted a takeoff from a grass runway that was 2,000 feet long with a 2 to 3 percent uphill slope. The departure direction was westerly. During the takeoff roll, the aircraft's tailwheel engaged the top strand of a barbed wire fence. Subsequently, the aircraft collided with 35-foot pine trees located west of the airstrip.
Pilot's Criteria and Aircraft Limitations
The pilot stated his personal criterion for a westerly departure from this runway was a wind of 8 knots or more from a westerly direction. According to the pilot's operating handbook (POH), the aircraft must be operated in the restricted category whenever it exceeds 3,300 pounds or when special agricultural equipment is installed. Performance data for operations under the restricted category is limited. Section 4 of the POH, which contains operating limitations, includes cautionary statements: (1) "The adverse effect of soft runways and long grass can only be determined by a series of takeoffs at increasing gross weights on a trial basis"; (2) "Conditions of high temperature, high altitude, rough takeoff surfaces, and terrain clearances at the end of the runway should obviously be taken into account in judging the proper takeoff gross weight of this aircraft"; and (3) "When agricultural equipment is installed, the takeoff ground run will not be effected significantly, but the air distance over an obstacle will be increased appreciably."
Takeoff performance data is limited to one chart labeled "Takeoff Distance with Dispersal Equipment," which assumes sea level, standard atmospheric conditions, zero wind, a hard surface, a level runway, and flaps at 10 degrees. No adjustments are provided for computing takeoff distances under other conditions.
The Takeoff and Collision
During the westerly takeoff attempt, the pilot reported that engine power appeared insufficient for clearing the trees, but he felt or heard no perceptible loss of power output. After the tailwheel caught the fence, the aircraft continued into the trees.
Engine Examination
The engine was sent to the Teledyne Continental Motors factory for a teardown inspection, with oversight from the Federal Aviation Administration. No abnormal conditions were found in the core engine or its components.