Event Description
Shortly after takeoff, the aircraft's climb performance deteriorated and the right engine began to overheat. The crew feathered the right engine and attempted to return to the airport. During this time, the radio transmitter became unintelligible, so tower personnel cleared the aircraft to land on runway 10 and asked the crew to key their microphone twice if they understood. The microphone was keyed twice. The aircraft entered a right downwind for runway 10 at a very low altitude. According to witnesses, the aircraft entered a steep bank while turning onto a base leg over water, the right wing tip struck the water, and the aircraft cartwheeled and crashed.
Investigation Findings
The copilot reported that after feathering the right engine, the minimum control speed (Vmc) of 84 knots was maintained; however, he believed the aircraft stalled just prior to impact. A teardown of the right engine revealed that the edge of the #8 piston and its piston rings had failed. Metal filings were found in the oil, and the oil pump was scored. There was evidence of oil starvation to the crankshaft journal, as well as piston slap associated with the ring failure. The investigation identified four occurrences:
- Occurrence #1: Loss of engine power (total) due to mechanical failure. Findings included failure of the piston rings, bearings, and master rod. Propeller feathering was performed, and a precautionary landing was initiated.
- Occurrence #2: Airframe/component/system failure/malfunction. The transmitter failed during the approach phase.
- Occurrence #3: Loss of control in flight. The pilot initiated a maneuver, but the investigation found that the pilot's airspeed was inadequate and his aircraft handling was improper.
- Occurrence #4: In flight collision with terrain/water. The aircraft descended uncontrolled into rough water.
Probable Cause
The probable cause was determined to be loss of engine power due to mechanical failure of the piston rings, bearings, and master rod; subsequent loss of control due to inadequate airspeed and improper aircraft handling by the pilot.