Accident Sequence
During an IFR arrival and descent, the pilot informed air traffic control that he had to feather one engine due to an oil leak and was attempting to descend. He reported descending through 5,300 feet. As the approach continued, the pilot stated that a go-around would be impossible because the hydraulic system was powered by the affected right engine. Subsequently, the pilot reported being at 1,500 feet and experiencing difficulty maintaining altitude. A witness observed the aircraft in a level attitude at low altitude before it dove toward the ground. The aircraft impacted in a steep descent just short of a long field and was consumed by fire. The right propeller was found feathered.
Investigation Findings
Examination of the engines revealed no evidence of oil starvation. The pilot's neighbor indicated that the pilot was aware of a hydraulic leak but was waiting for the annual inspection, which was due in September, to have it repaired. Inspection of the aircraft showed that the flaps were partially extended, the landing gear control was in the 'up' position, but the landing gear was down. According to the flight manual, in the event of a hydraulic failure downstream of the accumulator, the flap handle should be placed in 'neutral' to prevent unintentional gear and flap extension. The flap control could not be located.
The official probable cause findings are organized by occurrence sequence. The first occurrence was an airframe/component/system failure or malfunction, with the reason undetermined but involving a fluid leak. The second occurrence was a partial loss of engine power categorized as nonmechanical and intentional. The third occurrence was a forced landing, attributed to inadequate maintenance by company/operator management, operation with known deficiencies by the pilot in command, improper emergency procedure, low hydraulic system pressure, inadvertent gear extension, inadvertent lowering of flaps, and inability to level off. The fourth occurrence was a loss of control in flight due to failure to maintain airspeed (VMC). The final occurrence was an in-flight collision with terrain.
Probable Cause
The official probable cause findings are: airframe/component/system failure/malfunction (reason undetermined; fluid leak); loss of engine power (partial) - nonmechanical (intentional); forced landing (inadequate maintenance, operation with known deficiencies, improper emergency procedure, hydraulic system pressure too low, inadvertent gear and flap extension, inability to level off); loss of control - in flight (airspeed (VMC) not maintained); and in flight collision with terrain/water.