Stockbridge, MI, USA
N471RA
SCHWEIZER 269D
About a week or two before the accident flight in the helicopter, the pilot observed oil on the hangar floor that a mechanic determined had dripped from the helicopter’s exhaust stack collector. The helicopter had not been operated for about 2 weeks, and the mechanic noted that this was common when these helicopters are not operated frequently. A static engine test run did not reveal any anomalies. The engine produced some white smoke for a short time after startup consistent with the residual oil in the exhaust stack being burnt. After a recurrence of oil on the hangar floor several days later, the pilot decided to fly the helicopter to another location where it could be further examined by his mechanic. Before that flight, the pilot conducted another static engine ground run and a short test flight. During the short test flight, the pilot activated the cabin heater that produced slight smoke in the cabin. The pilot turned off the heater and opened a cabin window to vent the smoke before he made an uneventful landing. After the test flight, the pilot determined that the helicopter was safe for the intended flight to his mechanic’s shop. The pilot reported that shortly after he departed on the accident flight, when the helicopter was about 25 ft above ground level, he again detected smoke in the cabin when the cabin heater was turned on. The pilot intended to return to his departure point when the helicopter suddenly yawed to the right and impacted a snow-covered field, which resulted in substantial damage to the right side of the fuselage and the main rotor system. The pilot stated that the terrain elevation increased about 10 ft along his flightpath and that the snow-covered field had limited visible features to discern the helicopter’s height above the ground. He stated it was possible that he flew the helicopter into the ground because of a lack of ground references and his perceived height above the ground. Postaccident examination of the accident site and the wreckage revealed a short skid/drag mark in the snow aft and left of the helicopter, which was consistent with the forward portion of the right landing skid colliding with the ground while the helicopter was in forward flight. There was no evidence of a flight control issue or engine malfunction that would have contributed to the pilot’s inability to maintain control of the helicopter or make a normal landing. There was a slight oil residue observed in the exhaust duct. Although the presence of slight smoke in the cabin might have been distracting to the pilot, it could have been mitigated by turning off the cabin heater and opening a cabin window. It is likely the pilot did not maintain adequate clearance from the rising terrain while returning to the departure location after he detected smoke in the cabin.
On February 13, 2018, about 1415 eastern standard time, a Schweizer 269D helicopter, N471RA, was substantially damaged when it was involved in an accident near Stockbridge, Michigan. The pilot and his passenger sustained minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he noticed oil on his hangar floor sometime during the first week in February, and about 2 weeks after the helicopter was last flown. The pilot contacted his aviation mechanic who traveled to the pilot’s residence to inspect the helicopter and its engine. The mechanic reported that there was a small amount of engine oil on the hangar floor that had dripped from the exhaust stack collector. The mechanic noted that this was a common occurrence for these helicopters when not operated frequently. The mechanic added about ½ quart of engine oil to restore the oil system to its full level. The mechanic then asked the pilot to start and run the engine so that he could determine if the engine burned oil, leaked oil, caused a chip-detector light to illuminate, or if there were any anomalies to the engine oil pressure or temperature. The mechanic stated that the engine produced a white-colored smoke upon startup that continued for the first minute of engine operation, which he attributed to the previously accumulated oil in the exhaust collector being burnt by exhaust gases. The mechanic reported that after seeing no additional anomalies he asked the pilot to increase engine to 100% power for 5 minutes while he continued to look for any evidence of an oil leak or other engine anomaly. There were no anomalies observed during the engine power runup, or during the 2-minute engine cooldown before the pilot completed a normal engine shutdown. After the engine test run the engine oil remained at the full level and no additional oil was added. The pilot reported that several days later, he again observed some oil on his hangar floor and contacted his aviation mechanic to discuss the situation. The mechanic reported that he told the pilot that the engine’s No. 5 bearing seal likely needed to be replaced, and they agreed that the pilot would fly the helicopter to his shop (located at Ann Arbor Municipal Airport [ARB], Ann Arbor, Michigan) where he could complete the repairs. The mechanic stated that he asked the pilot to complete the same troubleshooting tasks that had been completed earlier (check the oil level and conduct engine run-ups) before the flight. The pilot stated that he waited several more days before he conducted the suggested engine run-ups. The pilot reported that before starting the engine he added engine oil to restore the oil system to its full level. The pilot stated that the engine started normally and that he did not observe any anomalies on the engine gauges, nor did he observe any oil leaks while the helicopter was operating on the ground. The pilot had an assistant on the ground who reported seeing smoke come from the helicopter upon engine startup; however, it was less than what he previously had seen when the pilot and his mechanic had completed their engine testing a few days earlier. The pilot then asked his assistant to observe the helicopter for oil leaks while he flew it in a hover for about 1 minute. The assistant did not observe any smoke, but he did observe residue where the oil had leaked previously. The pilot then decided to make a quick flight to further evaluate the engine operation. The pilot stated that he detected slight smoke in the cabin when he turned on the cabin heater while inflight. He noted that the slight smoke was likely from the oil leak into the exhaust collector. The pilot turned off the cabin heater and opened the small pilot-side window to clear the smoke from the cabin before he made an uneventful landing. The pilot reported that after his test flight, he decided the helicopter was safe for the flight to ARB and had his passenger board the helicopter. He noted that it was a sunny day and that the surface wind was negligible. The pilot stated that there was no smoke in the cabin before liftoff or while he hovered the helicopter before departure. The pilot reported that shortly after departure, he again detected smoke in the cabin after the cabin heater was turned on. The pilot estimated that the helicopter was about 25 ft above the ground and traveling about 15 mph at that time. The pilot intended to return to the departure point, but the helicopter suddenly yawed right and impacted the snow-covered field. The pilot reported that the engine continued to operate after the accident because he was unable to shut down the engine with the throttle twist-grip or turn off the fuel valve handle that had been damaged during impact. The pilot stated that he and his passenger exited the helicopter through the left cabin door with only minor injuries. The pilot noted that the engine continued to operate at “full speed” after he and his passenger had exited the helicopter. The pilot noted that the field elevation increased about 10 ft from his departure point to the accident site and that the approximately 30-acre snow-covered field had limited visible features to discern the helicopter’s height above the ground. He stated it was possible that he flew the helicopter into the ground because of a lack of ground references and his perceived height above the ground. The helicopter was found on its right side and had sustained substantial damage to the right side of the fuselage and the main rotor system. A postaccident examination of the accident site and the helicopter wreckage was completed by a Federal Aviation Administration (FAA) Airworthiness Inspector. The FAA inspector reported that he observed the helicopter laying on its right side in the snow-covered field. There was a short skid/drag mark in the snow aft and left of the helicopter. The forward portion of the right skid had fractured from the remaining skid. Portions of the main rotor blades were found 20-40 yards around the main wreckage. The snow was melted in the area and direction of the engine exhaust. Engine driveline continuity was confirmed for both the main and tail rotors. The tail rotor and horizontal stabilizer were relatively undamaged. The upper portion of the vertical stabilizer exhibited damage consistent with being struck by a main rotor blade. The engine drive gear and belt exhibited significant damage that was consistent with the engine continuing to run after impact. Collective, cyclic, and tail rotor control continuity was confirmed. There were no anomalies with the engine fuel control rigging. The engine compressor and power turbine rotated freely. There was a slight oil residue observed in the exhaust duct. The pilot had noted that 50 gallons of fuel were on board; a fuel sample did not exhibit any contamination.
The pilot’s failure to maintain adequate clearance from terrain while maneuvering the helicopter at a low altitude after departure. Contributing to the accident were the pilot’s distraction by the smoke in the cabin and the limited visible features in the snow-covered field to discern the helicopter’s height above the ground.
Source: NTSB Aviation Accident Database
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