Bulverde

The airplane's fuel tanks were fueled from a self serve fuel pump with 63 gallons of fuel prior to departure. The pilot initiated the takeoff roll from runway 30 with a 10 knot tailwind. The airplane was reported to have used the entire length of the runway during the takeoff roll. The airplane became airborne, attained a height approximately 100 feet agl, entered a descent, and subsequently, impacted the ground. A post accident fire consumed the airplane. Immediately following the accident, the pilot reported to local authorities that "he was leaving the airstrip and the plane stalled due to lack of airspeed." The 3,000-foot runway rises rapidly at its north end, such that the departure end of runway 30 was 50 feet higher than the approach end. At the time of the accident, the wind was from 130 degrees at 10 knots and the density altitude was 4,136 feet. Examination of the engine did not reveal any anomalies that would have precluded its operation prior to the accident.

After leveling at 5,500 feet, the standby power annunciator light illuminated, followed by loss of oil pressure. The pilot turned back toward the airport, but there was a progressive loss of engine power and the prop went to a feathered position. During an emergency landing at night, the aircraft hit a power line and trees, then crashed. During an engine teardown, disassembly of the reduction gearbox scavenge pump revealed that a retaining nut and tang washer (w/i the scavenge pump) had backed off and lodged between the spur gears, which resulted in a sheared scavenge pump drive shaft. In turn, this resulted in the loss of oil pressure and allowed the prop to feather.