History of Flight
On July 2, 2017, at approximately 1715 Pacific daylight time, a Robinson Helicopter Company R44 II helicopter, registration N488AS, came to rest in a pond near Bella Vista, California. The commercial pilot and one passenger sustained minor injuries, while two passengers sustained serious injuries. The helicopter sustained substantial damage. The aircraft was registered to Aero Leasing Inc. and operated by Air Shasta Rotor & Wing Inc. under 14 CFR Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight departed Redding, California around 1705, destined for a private residence in Bella Vista.
The pilot reported that the purpose of the flight was to attend a birthday party on private property, where he planned to give rides. Upon arrival, the pilot flew over the property and executed a left descending turn into the wind at an altitude of about 75-100 ft above ground level. He centered over a pond at an indicated airspeed of 70 knots, intending to make a right turn to set up for a landing into the wind at a predetermined landing zone. As he initiated the right turn, he heard three "pops," followed by the low rotor horn sounding and the caution light illuminating. The pilot assumed an engine power loss and immediately lowered the collective, pulled aft on the cyclic, and rolled the throttle to full open. The nose rose, and to avoid obstructions, he steepened the right turn. Realizing he did not have enough momentum to reach an open field and that rotor RPM was below 50%, he decided to land in the pond. During the descent, the tail struck a tree about 60 ft above the pond, pitching the helicopter nose-low. The pilot pulled aft on the cyclic and positioned the collective full down. About 10-15 ft above the water, he pulled full collective, and the helicopter struck the water in a nose-low attitude of about 5°, slightly left side low. The helicopter subsequently sank. The pilot estimated the forward speed at impact was 35-45 mph and was uncertain whether the engine was running.
Personnel Information
The 50-year-old pilot held a commercial pilot certificate with ratings for helicopter and gyroplane. His most recent second-class medical certificate was issued on June 24, 2017, with the limitation that he must have available glasses for near vision. The pilot reported a total flight time of 502 hours, with 350 hours in the accident helicopter make and model.
Aircraft Information
The helicopter, serial number 12538, was manufactured in 2008 and equipped with a Lycoming IO-540-AE1A5, six-cylinder, direct drive, horizontally opposed, normally aspirated, fuel-injected engine rated at 205 horsepower. The last annual inspection was completed on June 1, 2017, at a total airframe time of 2,117.74 hours, at which time the engine also received a 100-hour inspection. The engine had been installed new on June 5, 2008. At the time of the accident, both airframe and engine had accumulated 2,143.82 hours total time.
Meteorological Information
The nearest official weather reporting facility was at Redding, California, about 11 nautical miles north of the accident site. At 1653, the sky was clear, visibility was 10 miles, temperature was 100°F, dew point was 55°F, and the altimeter setting was 29.80 inHg.
Wreckage and Impact Information
Investigators from the Federal Aviation Administration, Robinson Helicopter Company, and Lycoming Engines examined the wreckage at the operator's facility.
Airframe: The collective and cyclic frictions were off, the governor was on, the clutch switch was engaged, the mixture was full rich, and the collective was nearly full up. The pedals had the left pedal forward of the right. The transponder and governor circuit breakers were found pulled out. Warning light filaments appeared normal, and the engine and rotor rpm gauges were at the bottom peg. Both fuel cells were intact, fuel caps secured, vent lines clear, main fuel shutoff valve on, and fuel selector turned freely. The gascolator screen had a small amount of lint. Approximately 28 gallons of fuel mixed with water was removed from the tanks. The sprag clutch bearing rotated smoothly, and the distance between the clutch actuator assembly anti-rotation scissors was 1.1 inches. All four V-belts were intact but displaced from their grooves. The main rotor mast appeared straight, but the shaft assembly had a slight forward tilt. The main rotor gearbox was intact. The forward flex coupling was straight; the intermediate flex coupling was bent and scored from contact with the upper fan scroll. Continuity and freedom of rotation were noted in the drive line from the main rotor shaft to the tail rotor disconnect. The tail rotor gearbox was intact. The main rotor head teetering bolt and coning bolts were secure, with a defined crush line across the elastomeric portion of both teeter stops. Droop stops and tusks were in place. Main rotor flight control continuity was confirmed. The right pedal push-pull tube was disconnected near the bellcrank, with the rod end pushed through the fiberglass chin. All other tail rotor flight controls were secure. The tail rotor pitch change slider was free.
Engine: No evidence of contact between the starter ring gear and oil coolers was found. The fan scroll was crushed and fractured on the forward side, with a light score mark inside where the fan contacted the scroll. Paint on the outer lips of the fan was rubbed off. The upper scroll had a jagged tear and score marks from contact with the intermediate flex plate. The A185-1 bracket was found loose with one end detached, and rivet holes on the detached end were elongated. The crankshaft rotated easily by hand. Bottom spark plugs were removed, and thumb compression was observed in proper order in all six cylinders. Valve train continuity was established, and normal lift action was seen. Clean, uncontaminated oil was observed at rockerbox areas. Mechanical continuity was established through the rotating group. Combustion chambers were undamaged with no evidence of foreign object ingestion or detonation. Spark plugs showed coloration consistent with normal wear. Both magnetos were securely clamped, and the ignition harness was secure. Magneto-to-engine timing could not be ascertained due to water immersion. The magnetos were removed; they produced inconsistent spark when manually rotated. Follow-up examinations at Robinson Helicopter Company and Continental Motors Inc. revealed corrosion on some parts, likely from time between water removal and examination. After cleaning, satisfactory test results were obtained.