Accident Overview
On February 13, 2018, about 1415 eastern standard time, a Schweizer 269D helicopter, registration N471RA, was substantially damaged during an accident near Stockbridge, Michigan. The helicopter, operating as a personal flight under Title 14 Code of Federal Regulations Part 91, sustained damage to the right fuselage side and main rotor system. The pilot and one passenger received minor injuries.
Preceding Events
During the first week of February, the pilot noticed oil on his hangar floor approximately two weeks after the helicopter's last flight. An aviation mechanic inspected the helicopter and engine, finding a small amount of engine oil on the floor that had dripped from the exhaust stack collector. The mechanic noted this as a common occurrence for the helicopter type when not operated frequently. He added about half a quart of oil to restore the system to full level. At his request, the pilot started the engine, which produced white smoke for the first minute, attributed to burning accumulated oil in the exhaust collector. The mechanic then had the pilot run the engine at 100% power for five minutes while observing for leaks or anomalies; none were found. After a two-minute cooldown, the engine was shut down normally. The oil remained at the full level.
Several days later, the pilot again observed oil on the floor. The mechanic suggested that the No. 5 bearing seal likely needed replacement and recommended flying the helicopter to his shop at Ann Arbor Municipal Airport (ARB). He asked the pilot to repeat the previous troubleshooting steps before the flight.
Pilot's Actions
The pilot waited several more days before performing the engine run-ups. Before starting, he added oil to restore the full level. The engine started normally, with no gauge anomalies or oil leaks observed on the ground. An assistant on the ground saw smoke upon startup, but less than during the earlier test. The pilot then hovered for about one minute while the assistant watched for leaks; no smoke was seen, but residue was noted where oil had previously leaked. The pilot decided to take a quick flight to further evaluate engine operation. During flight, he detected slight smoke in the cabin when the cabin heater was turned on, likely from oil in the exhaust collector. He turned off the heater and opened the pilot-side window to clear the smoke before making an uneventful landing.
After the test flight, the pilot judged the helicopter safe for the flight to ARB. He boarded his passenger. The day was sunny with negligible surface wind. Before liftoff and during hover, no smoke was in the cabin. Shortly after departure, the pilot again detected smoke after turning on the cabin heater. At that time, the helicopter was about 25 feet above ground and traveling about 15 mph. The pilot intended to return to the departure point, but the helicopter suddenly yawed right and impacted a snow-covered field. The engine continued to run at full speed after impact because the pilot could not shut it down; the throttle twist-grip and fuel valve handle were damaged during impact. The pilot and passenger exited through the left cabin door with minor injuries.
Postaccident Examination
The field elevation increased about 10 feet from the departure point to the accident site. The approximately 30-acre snow-covered field lacked visible features to discern height above ground. The pilot speculated that he may have flown the helicopter into the ground due to lack of ground references and perceived altitude.
The helicopter came to rest on its right side. A Federal Aviation Administration airworthiness inspector conducted a postaccident examination. The inspector observed the helicopter lying on its right side with a short skid/drag mark aft and left. The forward portion of the right skid was fractured. Main rotor blade fragments were found 20 to 40 yards around the wreckage. Snow was melted in the area and direction of the engine exhaust. Engine driveline continuity was confirmed for both main and tail rotors. The tail rotor and horizontal stabilizer were relatively undamaged. The upper vertical stabilizer showed damage consistent with a main rotor blade strike. The engine drive gear and belt were significantly damaged, consistent with the engine running after impact. Collective, cyclic, and tail rotor control continuity was confirmed. No anomalies were found in engine fuel control rigging. The engine compressor and power turbine rotated freely. Slight oil residue was observed in the exhaust duct. The pilot reported 50 gallons of fuel on board; a fuel sample showed no contamination.