20010827029279A

(-23) Aircraft N64KS was involved in an accident in edgewater, Florida on August 27th, 2001. N64KS was a two place troy a. woodland, model sky raider ii amateur-built aircraft. A Bombardier Rotax model 503 two-cycle engine that develops approximately 50 horsepower and a powerfin three bladed composite propeller are installed on this aircraft. Witnesses stated that the aircraft appeared to have experienced a loss of power during climb out and that the aircraft went into a steep turn, back to the airport, at a low altitude whereupon it descended in a steep attitude and impacted the ground just outside of the north fence of the airport. Continuity of the flight and engine control system was checked with no discrepancies noted. The impact caused the elevator to be stuck in the full nose up position, and the throttle to be in the full power position. The throttle controls both of the bing carburetors and the oil injection pump. The fuel lines were pulled loose on impact, which allowed the fuel to drain from the tanks. The fire department hosed the fuel from the aircraft and surrounding area. This engine utilizes an oil injection system that introduces oil into the fuel before the fuel enters the combustion chamber, providing a specified fuel to oil mixture. There was approximately two ounces of oil remaining in the oil supply tank, which is not sufficient to maintain oil flow to the injection pump. There was no oil in the supply lines from the oil tank to the oil pump or in the oil lines from the pump to the engine. The passenger stated that at no time did he observe the pilot check the oil quantity in the oil supply tank prior to flight. The engine was disassembled to the extent that the cylinder bores and the pistons could be inspected for damage cuased by lack of oil in the fuel oil mix. The inspection of the above referenced parts did not reveal any abnormal distress. Upon consulting with personnel at the Rotax overhaul facility located in searing, FL., it was determined that this model engine can, in fact, experience a power loss due to improper oil/fuel mix or lack of oil supply and not display cylinder or piston distress. The engine lost power but did not stop rotating evidenced by the way in which all three-propeller blades were sheared off upon impact. The bing carburetors were disassembled to check the condition of the needles and internal operating parts; no discrepancies were noted. There was a trace amount of fuel remaining in the carburetor bowls and that fuel appeared by touch and evaporation characteristics to contain a certain amount of oil. Premixing the gasoline in the fuel tanks with the prescribed amount of oil is an alternate method of providing the engine with the proper fuel/oil mixture; if this method is employed, oil need not be maintained in the oil supply tank, however, it could not be determined if the oil was premixed in the fuel tanks prior to this flight. (.4) after takeoff, the airplane climbed to approximately 200 feet above ground level, then lost engine power. The pilot attempted to return to the runway. During the maneuver, airspeed was not maintained, and the airplane stalled and dove straight into the ground. Fuel was observed leaking from the wreckage at the accident site. The engine was removed for examination, and the drive train rotated freely when manipulated by hand. All three propeller blades were found broken off the hub. Examination of the engine and flight controls revealed no evidence of mechanical malfunction. Diazepam (valiu m), a prescription medication, was detected during the toxicological examination.