Park Rapids, MN, USA
N56MC
Bell 206B-III
The helicopter sustained substantial damage on impact with water while maneuvering over a glassy lake. The pilot stated, "Potato Lake selected for low altitude water/shoreline footage. Did high recon, no observed boat traffic in conflict with flight path over water at approx 40 to 50 ft. Commenced with descent profile of 80 mph and 600 [feet per minute]. The descent was to continue until treetop level then terminate descent and cruise over water for length of lake. Flight path was south to north with planned airspeed of 60 - 80 mph, then climb out. Reached target altitude confirmed with left and right shoreline sight picture, raised collective pitch with [simultaneous] forward cyclic pressure to commence over water cruise. Engine appeared non-responsive to power demand. Descent was not arrested. Added additional collective, no response to power demand. Leveled aircraft and impacted water with forward velocity." The front left seat passenger stated, "The pilot did not give us any pre-flight safety briefing or instructions. The pilot did not demonstrate or explain how to use the seat belts or how to egress from the helicopter in case of an emergency. ... Shortly after takeoff, I noticed were flying very low over the lake. Suddenly the helicopter abruptly dove down nose first crashing into the lake. The helicopter quickly began to sink into the water. ... I could not unbuckle the safety harness strap. My clothing was getting very heavy and I began to swallow water uncontrollably. I thought I was going to die. I continued to unsuccessfully struggle with the safety harness. Finally, somehow, I was able to wiggle out of the buckled safety harness." Wind was calm, sky condition clear, and the temperature was 20 degrees C. An on-scene investigation of the recovered wreckage revealed no pre-impact anomalies. A study of an on-board video revealed sounds consistent with the gas producer section of the engine and the main rotor system. Both rear passengers were not wearing their seat belts.
HISTORY OF FLIGHT On September 27, 2001, about 1230 central daylight time, a Bell 206B-III, N56MC, operated by EAC Helicopters, Inc., sustained substantial damage on impact with water while maneuvering over Potato Lake, near Park Rapids, Minnesota. The pilot reported that the business flight was operating under 14 CFR Part 91. Visual meteorological conditions prevailed at the time of the accident. The commercial pilot reported that he and three passengers sustained minor injuries. No flight plan was on file. The local aerial photography flight departed from Park Rapids Municipal Airport (PKD), Park Rapids, Minnesota, at 1220 and was maneuvering at the time of the accident. The pilot stated: Departed Park Rapids enroute to Lake Itasca (20 mi. north). Potato Lake selected for low altitude water/shoreline footage. Did high recon, no observed boat traffic in conflict with flight path over water at approx 40 to 50 ft. Commenced with descent profile of 80 mph and 600 [feet per minute]. The descent was to continue until treetop level then terminate descent and cruise over water for length of lake. Flight path was south to north with planned airspeed of 60 - 80 mph, then climb out. Reached target altitude confirmed with left and right shoreline sight picture, raised collective pitch with [simultaneous] forward cyclic pressure to commence over water cruise. Engine appeared non-responsive to power demand. Descent was not arrested. Added additional collective, no response to power demand. Leveled aircraft and impacted water with forward velocity. The passenger in the front left seat stated: We discussed the film project and the flight itinerary with the pilot prior to takeoff. During this pre-flight meeting, I informed the pilot that we wanted to film the headwaters. The pilot did not give us any pre-flight safety briefing or instructions. The pilot did not demonstrate or explain how to use the seat belts or how to egress from the helicopter in case of an emergency. After boarding, I sat next to the pilot and my two co-workers sat in the back of the helicopter. Shortly after takeoff, I noticed we were flying very low over the lake. Suddenly the helicopter abruptly dove down nose first crashing into the lake. The helicopter quickly began to sink into the water. For some time, I lost consciousness and when I awoke, I was descending further down into the water. I began to struggle to unsnap my seatbelt. At that point I realized I was trapped to my seat sinking and that my seat had broken off from the plane. I could not unbuckle the safety harness strap. My clothing was getting very heavy and I began to swallow water uncontrollably. I thought I was going to die. I continued to unsuccessfully struggle with the safety harness. Finally, somehow, I was able to wiggle out of the buckled safety harness. Once free from the seat, I was so deep into the water that I could not tell which way was up to the surface. I began to just swim, not knowing which direction to go in. Eventually, I emerged at the lake's surface. I was the last one to reach the surface. When I emerged I saw my two co-workers helping the pilot to stay afloat. The right rear passenger stated: While I was riding in the helicopter, I did not wear seat belt since I was shooting with video camera. The flight began, and after about 10 minutes the helicopter suddenly began to lose altitude over Potato Lake. Since the helicopter did not exhibit any other unusual signs such as an abnormal noise or smoke, and was not falling in a way that suggested it was going to crash, I believed that it was probably falling due to operation by the pilot. In the past, I occasionally have had experiences where a pilot will fly lower to show off for us, and on this occasion as well I believed that the pilot was demonstrating to us his flying skill. Since I had not told him that we planned to shoot lakes on the way from a low altitude or anything like that, I thought that perhaps we might have arrived already at Lake Itasca, and after exchanging glances with [the left rear passenger], I turned to the intercom and was about to ask, 'Have we arrived at Lake Itasca?' At that moment, the helicopter fell into the lake. The left rear passenger stated: The helicopter took off at noon. At first I had my seat belt on. Five to 10 minutes after take off we could see the lake as a dot right in front of us, and [the front seat passenger] began to film this using a video camera. I took off my seatbelt so that I could take the photographs to be used for the show, and began taking photographs with my camera. From the time the helicopter took off to the time it crashed there was not conversation between the people inside. After a few minutes, I could see a large lake right in front of me. I was viewing the lake through the finder on my camera and saw the lake getting bigger and bigger, so I realized the helicopter was going down. The helicopter was in no particular state of instability so I thought the pilot was causing it to dive down by design. Nonetheless, since Lake Itaska, the subject of filming, was supposed to be farther away, I thought to myself, 'Why is the helicopter going down here?' and I looked over at [the right rear passenger]. Immediately thereafter I heard the intercom switch being turned on and then right after that I heard a 'bang!' and received a heavy jolt. PERSONNEL INFORMATION The pilot held a commercial pilot certificate with a rating for rotorcraft/helicopter. He held a certified flight instructor certificate for rotorcraft/helicopter. He also held a private pilot certificate with a rating for airplane single engine land. The pilot did not possess an instrument rating. The pilot stated that he had accumulated 3,032 hours of total flight experience, 2,992 hours of which were in rotorcraft. The pilot listed 538 hours of flight experience in this make and model of helicopter. The pilot reported his most recent biennial flight review was completed in a Bell 206B-III on July 24, 2001. The pilot's most recent Federal Aviation Administration (FAA) second-class medical certificate was issued on September 26, 2001. The pilot reported that the medical had a limitation of "corrective lenses." AIRCRAFT INFORMATION The 206B-III helicopter, serial number 3573, was a single engine, two-bladed semi-rigid main rotor, five-seat aircraft, which was manufactured by Bell Helicopter. It was powered by an Allison 250-C20J, serial number CAE-270014, turbo shaft, reverse flow engine, that had a maximum sea level rating of 420 horsepower. The pilot reported that the airframe had 3,182.2 hours of total flight time and that the engine had accumulated 1,444 hours since its last overhaul. The pilot stated that the last inspection the helicopter received was a 100-hour inspection on July 23, 2001. The pilot reported that the helicopter accumulated 12 hours of flight time since that inspection. METEOROLOGICAL INFORMATION At 1253, the PKD weather was: Wind calm, visibility 10 statute miles, sky condition clear; temperature 20 degrees C; dew point 4 degrees C; altimeter 30.17 inches of mercury. At 1253, the calculated density altitude at PKD was 2,067 feet. WRECKAGE AND IMPACT INFORMATION The recovered helicopter wreckage was stored at PKD. Front cabin components to include the collective, console, and the cyclic stick were not recovered. The NTSB examined the recovered wreckage at PKD on November 5, 2003. The tailcone was separated from the aft fuselage. Control push-pull tubes were traced from the rotor pedals to the tail rotor. All separations in the control tubing were consistent with overload. The cyclic and collective push-pull tubes were intact beneath the aft portion of the pilot seat up through a structural column up to their servo actuators. Push-pull tubes from the servo actuators to the swashplate were traced. All separations in the control tubing were consistent with overload. Pitch link assemblies showed separations in overload. The mast exhibited a separation consistent with a torsion overload. The section of mast retained by the main rotor hub assembly exhibited impressions consistent with hub assembly contact. The main rotor blade with a red color code on it exhibited damage from the inner third to its outboard edge. The main rotor blade with the white color code on it had damage midspan. The transmission and tail rotor gearboxes were found seized. With a force applied, both were able to turn. The isolation mount cover was found with linear gouges in the same direction and location as the plane of rotation of the transmission input pinion's adapter to the engine driveshaft. The tail rotor pitch change assembly moved when its control push-pull tube was moved at the tailcone's separation from the aft fuselage. The engine was found seized. The compressor section's case half was removed and no anomalies were detected in that section. The power turbine blades visible through the exhaust outlets exhibited no anomalies. The engine's freewheeling unit was operational and the engine was able to turn when a rotational force was applied to that freewheeling unit. Continuity was observed between the freewheeling unit and the power turbine. Continuity was established when the compressor was rotated by hand and rotation of the gas producing turbine was confirmed by the movement of safety wire inserted in a thermocouple's port. A fluid consistent in color and smell to Jet A fuel was found in the airframe mounted fuel filter and in the engine fuel filter. A liquid was found in the fuel line to the fuel nozzle. The fuel nozzle was disassembled and its screen was deformed. No other pre-impact anomalies were detected during the investigation. SURVIVAL ASPECTS The right rear passenger stated that he did not wear seat belt since he "was shooting with video camera." The left rear passenger stated, "I took off my seatbelt so that I could take the photographs to be used for the show, and began taking photographs with my camera." TESTS AND RESEARCH A video camera was recovered from Potato Lake and was sent to the National Transportation Safety Board's Vehicle Recorder Division for review. The recorder division produced a study. Excerpts from the video study stated: Description of Recording Approximately 147 seconds of video and 2 channels of audio were recovered from the tape. The contents of the video suggest that the camera was on and recording up to the time of the accident. The 147 seconds are not continuous. There are two segments, both were recorded while the helicopter was airborne and both appear to be from about the same general camera location/orientation. Video The camera view appears to have been pointed out the right side of the helicopter, with little or no tilt up or down. The view is of landscape consisting primarily of trees and lakes. No portion of the helicopter is in view at any time during the recording. The last portion of the recording is consistent with a descent over a lake, with no large or abrupt changes in the camera view noted. Small changes in the view (such as the angle of the horizon) occur just before the recording ends, however similar changes can also be seen earlier in the recording. Audio The majority of the audio contains a relatively constant sound similar to wind moving over a microphone surface. No obvious engine or rotor noise could be heard. No voices, warning sounds or alerts could be heard at any time. The appearance of the lake was glassy as exhibited on still images in the video study. A spectrum plot of audio frequencies on the video tape was produced. The plot exhibited sounds consistent with the gas producer section of the engine. A rapid, periodic broad band sound was detected. That periodic sound was consistent with the main rotor system. The video study is included with the docket information associated with this factual report. The engine's fuel nozzle was sent to Dallas AirMotive for examination. The nozzle produced a flow within serviceable specifications during the examination. That examination is included with the docket information associated with this factual report. ADDITIONAL INFORMATION The parties to the investigation included the FAA, Bell Helicopter Textron Inc., and Rolls-Royce Corporation. The aircraft wreckage and the retained part were released to an insurance company representative.
The pilot not maintaining altitude/clearance when he maneuvered above the glassy lake. A factor to the accident was the glassy lake condition.
Source: NTSB Aviation Accident Database
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