CHI07FA114

The pilot's failure to maintain a proper approach glidepath, which resulted in a settling-with-power flight condition. Contributing to the accident was the dark night light condition.

The helicopter was en-route to the pilot's residence located on a lake. The accident occurred during a dark night in visual meteorological conditions. As the helicopter crossed the lake, it was observed descending steadily towards the water, hovering for about 1-2 seconds, then falling vertically from approximately 40-50 feet into the lake. The helicopter impacted the water about 1/4 mile from the intended landing area. The pilot and his passenger survived the impact, but died of hypothermia due to their prolonged exposure to cold lake water. The investigation revealed no preimpact mechanical malfunctions or anomalies that would have prevented the normal operation of the helicopter. Outside visual reference for airspeed and rate of closure may not be available at night, especially when approaching an unlighted landing area. A pilot's failure to monitor altitude, airspeed, and rate of descent during an approach can result in a settling-with-power condition. The helicopter's flight profile before impact was consistent with a settling-with-power flight condition.

HISTORY OF FLIGHT On April 22, 2007, at 2031 central daylight time, a Robinson R44 II helicopter, N382BT, owned and piloted by a private pilot, was substantially damaged when it impacted water during approach to a residence on the shore of Bass Lake, Indiana. Night visual meteorological conditions prevailed at the time of the accident. The personal flight was operating under the provisions of 14 Code of Federal Regulations (CFR) Part 91 without a flight plan. The pilot and his passenger were fatally injured. The flight departed the Starke County Airport, Knox, Indiana, at 2023 after refueling. Witnesses reported hearing the helicopter approach from the northwest and continuing across the lake toward the pilot's residence. As the helicopter crossed the lake, it was observed to descend steadily towards the water, hover for about 1-2 seconds, then fall vertically from approximately 40-50 feet into the lake. The helicopter impacted the water about 1/4 mile from the intended landing area. PERSONNEL INFORMATION According to Federal Aviation Administration (FAA) records, the pilot of N382BT, age 45, held a private pilot certificate with a rotorcraft-helicopter rating. He was not instrument rated. The pilot's last aviation medical examination was completed on May 23, 2006, when he was issued a third-class medical certificate with no limitations or restrictions. The pilot's most recent flight logbook entry was dated March 30, 2005, after completing the Robinson Helicopter Pilot Safety Course at the factory in Torrance, California. As of this entry, he had accumulated 321.6 hours total flight time, of which 224.2 hours were as pilot-in-command. All of his flight experience was in helicopters, including 308.4 hours in the accident make/model and 13.2 hours in a Robinson R22 Beta. He had accumulated 36.9 hours at night. In addition to his permanent flight logbook, the pilot kept a contemporaneous record of his flights. The recorded flight times corresponded with the accident helicopter's Hobbs hour meter. According to aircraft and pilot records, he was the only individual to fly the accident helicopter. The final entry was dated August 7, 2006, which indicated his cumulative flight experience in the accident helicopter was 475.9 hours. At the time of the accident the helicopter's Hobbs hour meter read 513.3 hours. AIRCRAFT INFORMATION The accident helicopter, N382BT, was a 2003 Robinson R44 II Raven, serial number (s/n) 10107. The helicopter was a four-seat, single-engine helicopter that was equipped with a skid type landing gear. The helicopter was powered by a 245-horsepower Lycoming IO-540-AE1A5, s/n L-28763-48A, reciprocating engine. The helicopter's maximum gross weight was 2,500 pounds. The helicopter was issued a Standard Airworthiness Certificate on June 25, 2003. The pilot was the sole operator of the helicopter. A review of the maintenance records showed that the helicopter had undergone an annual inspection on September 24, 2006. At the time of the accident, the airframe and engine had accumulated 513.3 hours in service. The helicopter had accumulated 36.7 hours since the last maintenance inspection. Fueling records indicated that the helicopter was fueled with 31.35 gallons of 100 low-lead aviation fuel before departing on the accident flight. A fuel sample was taken after the accident that was free of particulate or water contamination and was blue in color. A review of the maintenance logbook records found no history of unresolved airworthiness issues. METEOROLOGICAL INFORMATION The closest weather reporting facility was at the Porter County Municipal Airport (KVPZ), Valparaiso, Indiana, located about 23 miles northwest of the accident site. The airport was equipped with an automated surface observing system (ASOS). At 2053, the KVPZ ASOS reported the following weather conditions: Wind 190 degrees true at 10 knots; visibility 10 miles; sky clear; temperature 21 degrees Celsius; dew point 8 degrees Celsius; altimeter setting 29.94 inches of mercury. The sunset occurred at 1934 and the end of civil twilight was at 2003, according to astronomical data provided by the U.S. Naval Observatory. The accident occurred at night with 34 percent of the moon's visible disk illuminated. WRECKAGE AND IMPACT INFORMATION The helicopter was found submerged in 18 feet of water, located about 1/4 mile from the pilot's landing area on the northeast side of the lake. The helicopter was located about 1/2 mile from the northwest shoreline. The wreckage was salvaged from the lake and secured at the departure airport before the NTSB investigator arrived on scene. The main fuselage structure was found resting upright on its landing skids. The fuselage structure, cabin, landing skids, engine and main transmission had sustained minor impact damage. The altimeter's Kollsman window was set to 29.86 inches of mercury. Examination of the airframe and flight control system components revealed no evidence of a pre-impact mechanical malfunction. The main rotor blades remained attached to their respective blade grips. The main transmission rotated freely when the main rotor system was rotated. The sprag clutch operated as designed. Flight control continuity was established from the cyclic and collective cockpit controls to the swash plate assembly. The three hydraulic flight control actuators had minor impact damage. One of the blade pitch change links was fractured. The fracture surface was consistent with an overload failure. The entire tail boom was separated from the main fuselage. Flight control continuity was established from the anti-torque pedals to the tail rotor assembly. All observed separations exhibited fracture surfaces consistent with overload failure. The tail rotor driveshaft was fractured where the tail boom had separated from the fuselage. The driveshaft fracture exhibited signatures consistent with overload. The tail rotor gearbox rotated freely when the tail rotor was rotated. One of the tail rotor blades was missing a majority of its span. The fractured blade root exhibited signatures consistent with an overload failure. The missing blade portion was not recovered. The engine remained attached to its mounts in its normal airframe position. The engine incurred only minor impact damage. Water drained out of all cylinders when the lower sparkplugs were removed. There was circumferential rubbing on the engine cooling fan and on the engine pulley that drove the transmission belts. The throttle and mixture controls were continuous from the cockpit to the engine fuel servo. The engine was rotated by turning the cooling fan. Crankshaft continuity was confirmed to all engine cylinders, rear gear assemblies, and the valve train. All six cylinders exhibited compression and suction during crankshaft rotation. Both magnetos were fouled with water. The magnetos were removed, drained, and dried. The dried magnetos produced spark on all leads when rotated. Examination of the wreckage did not reveal any anomalies associated with a pre-impact failure or malfunction. MEDICAL AND PATHOLOGICAL INFORMATION The passenger was recovered and pronounced dead on the night of the accident. The pilot's body was not immediately located and was recovered 10 days after the accident. Autopsies were performed on both occupants. The cause of death for both occupants was attributed to hypothermia. The hypothermia was due to, or as a consequence of, their prolonged exposure to cold water. The FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma, performed toxicology tests on the pilot. The specimens were received in a state of putrefaction. No carbon monoxide or cyanide was detected in blood. 19 mg/dL of ethanol was detected in blood, 22 mg/dL of ethanol was detected in muscle, and 26 mg/dL of ethanol was detected in brain. 5 mg/dL of N-Butanol was detect