CEN18LA106 · 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.

Verbatim NTSB analysis and probable cause from the NTSB dataset