Accident Overview
On September 17, 2010, at approximately 0023 central daylight time, a Robinson R44 II helicopter, registration N145DM, was destroyed when it struck the waters of Island Lake near Duluth, Minnesota. The flight was conducted under 14 Code of Federal Regulations Part 91 without a flight plan in night visual meteorological conditions. The commercial pilot, who was the sole occupant, sustained minor injuries. The helicopter had departed from a beach on Island Lake and was in the initial climbout at the time of the accident. The intended destination was Duluth International Airport (DLH), about 10 miles south.
Pilot Statement
The pilot reported that he had flown from DLH to the beach site to show the helicopter to prospective clients. After spending several hours, he decided to return. He lifted off into a hover and established a 600-foot-per-minute rate of climb at 60 knots airspeed. During the climb, he experienced a "sinking feeling in the seat all of a sudden" and noticed the vertical speed indicator indicated a descent. Flight instruments showed the helicopter at 60 knots and in level flight. He increased engine power but continued descending. After a second instrument check, all indications remained the same. The pilot thought the helicopter might have encountered a microburst. He could not determine the helicopter's exact height above the water due to night lighting conditions and did not flare before impact. The helicopter struck the water at about 60 knots.
Witness Observation
A witness reported that the start, warm-up, liftoff, and initial climb appeared normal. The entire event lasted about 10 seconds, with concern apparent only in the final 2 seconds as the distance between the helicopter's navigation lights and their reflection on the water decreased rapidly. The witness noted the helicopter appeared level and in controlled flight throughout.
Weather and Lighting
Weather conditions recorded at DLH at 2355 included scattered clouds at 11,000 feet above ground level, 10 miles visibility, and wind from 180 degrees at 4 knots. At 0055, conditions were broken clouds at 10,000 feet, 10 miles visibility, and wind from 240 degrees at 7 knots. The moon set at 0058, about 35 minutes after the accident, and was in a waxing gibbous phase with 73 percent of the visible disk illuminated. The witness described the night as dark but with a distinguishable horizon, and did not consider conditions adverse for the return flight.
Post-Accident Examination
A post-accident examination of the helicopter revealed no anomalies consistent with a pre-impact failure or malfunction.
Pilot Qualifications
The pilot informed FAA inspectors that he had executed a similar night departure in June, though the accident night was darker. He did not hold an instrument rating but was reportedly working toward it and had accumulated about 30 hours of instrument flight time.