History of Flight
On October 25, 2019, at about 1541 mountain daylight time, an Enstrom 280F helicopter, registration N280F, was substantially damaged in an accident near Jordan Valley, Oregon. The pilot was fatally injured, and the pilot-rated passenger sustained serious injuries. The helicopter was being operated as a personal flight under Title 14 Code of Federal Regulations Part 91.
According to the passenger, the flight was intended to go from their home base at Caldwell Industrial Airport (EUL) in Caldwell, Idaho, toward the Owyhee Mountain Range and Reservoir, a route they had taken multiple times. The pilot had already moved the helicopter out of the hangar when she arrived. They boarded, taxied to the fueling facility, and the pilot added 22.5 gallons of fuel. The departure to the southwest was uneventful. After reaching the mountain range, they observed wild horses, and the pilot performed an orbit while the passenger took photos. They then proceeded southwest.
A few minutes later, the pilot calmly stated that the "rpm" was low. The passenger was not initially concerned, but soon the pilot became nervous and began manipulating the collective control. There was no change in sound or feel, but the passenger saw an instrument needle left of the normal green zone. The helicopter then rapidly descended, yawed right, and struck the ground right side down.
Family members contacted law enforcement when neither occupant returned home, and the wreckage was located the following morning.
Automatic Dependent Surveillance-Broadcast (ADS-B) data showed that the helicopter maintained a terrain clearance of 350 to 900 ft agl after departure, with a groundspeed of about 100 mph. As it entered the mountain range, it climbed while slowing to 85 mph, then followed the terrain with clearances varying between 0 and 100 ft agl. At 18 minutes after takeoff, about 25 miles southwest of EUL, it began an orbit at a GPS altitude of about 4,900 ft (50-200 ft agl). After the orbit, it departed to the southwest at about 5,000 ft msl, maintaining a terrain clearance of 0 to 50 ft agl at about 70 mph for the remaining 2 miles.
Wreckage and Impact Information
The helicopter came to rest on its right side on a heading of about 330° magnetic, about 500 ft south of the last ADS-B target at an elevation of 4,917 ft msl. The first identified point of impact was a disrupted earth area 25 ft north of the main wreckage, containing canopy plexiglass and cabin contents. Imprints matching the landing gear skids were forward of the disruption, beyond which were perpendicular slash marks from main rotor blade tip contact.
All three main rotor blades remained attached with 30° upward bending, leading edge and chordwise abrasion. Examination of the airframe and flight controls revealed no mechanical malfunctions or anomalies that would have precluded normal operation.
The engine sustained minimal damage with no evidence of catastrophic internal failure. Engine controls were continuous. The inlet air filter was unobstructed. The dual magneto was undamaged and timing met specifications. Spark plugs showed normal wear. Five cooling fan blades were bent about 90° opposite rotation, with scoring on the fan shroud. The fuel system had no anomalies, and fuel was recovered from both tanks.
The main transmission belt engagement clutch was fully engaged with no significant drive belt degradation. The freewheeling unit allowed correct rotation direction. The tachometer drives were intact and operational; subsequent testing found no anomalies. The helicopter was not equipped with an audio or visual low rotor-rpm warning system.
The engine air induction system included an air filter assembly connected to the fuel injection servo via a flexible intake hose. The hose was a 3-inch diameter "Silfab-2" type with a spring steel helix bonded between fiberglass silicone rubber liner and cover, the outer surface double-wound with a fiberglass cord. Detailed examination revealed that the outer cover and cord had abraded, exposing the steel helix over about half the hose length. In some areas, the helix was visible for more than half the circumference, allowing the liner and cover to flex inward and partially obstruct airflow.
The inspection guide for the 100-hour/annual inspection required: "Inspect the flex duct and fuel servo adapter for condition and security of installation."
Additional Information
The FAA Helicopter Flying Handbook height/velocity diagram indicates dangerous combinations of airspeed and height above ground. At the accident weight of about 2,350 lbs, the operator's manual height/velocity diagram applies. The manual states: "When an engine failure occurs at low altitude and low airspeed, sufficient altitude may not be available to increase rotor rpm..."
The passenger assumed the helicopter was about 500 ft agl near the horses, based on an iPad with ForeFlight that provides 500 ft AGL alerts when descending through 500 ft from above 1,000 ft. However, ADS-B data showed the helicopter never exceeded 900 ft agl during the flight, so the alert would not have been activated.
Medical and Pathological Information
The pilot's autopsy, performed by the Department of Pathology at Saint Alphonsus Medical Center – Ontario, determined the cause of death as multiple traumatic injuries due to helicopter crash, manner accidental. Toxicological testing found no impairing drugs.
Survival Aspects
The helicopter was equipped with a 406 AF-COMPACT emergency locator transmitter (ELT) manufactured by Kannad, but no activation signal was received by the Air Force Rescue Coordination Center. The installation instructions require the ELT to be mounted 45° relative to the yaw axis on a structural member, with an external antenna on top of the helicopter. On-site examination found the ELT mounted on the left floor panel of the enclosed aluminum baggage compartment, connected to a portable auxiliary whip antenna inside the baggage compartment. The ELT power switch was in the "armed" position and emitted an audio tone consistent with activation. Testing showed the unit passed all tests and the battery had sufficient charge. The ELT was not registered to the current owner as required, but to the previous owner.
The pilot and passenger used factory-installed 3-point harnesses. The helicopter was not equipped with emergency survival equipment; the passenger was wearing pants and a shirt, having left her jacket in the hangar.