Introduction
On September 3, 2011, at approximately 1215 mountain daylight time, an Enstrom 280FX helicopter, registration N280AD, was substantially damaged when it impacted terrain following a loss of engine power near Heber City, Utah. The commercial pilot and two passengers were seriously injured. The helicopter was operated by High Velocity Aviation under 14 Code of Federal Regulations Part 91 as a local air-tour flight. Visual meteorological conditions prevailed, and the flight had departed from Heber City Municipal Airport about nine minutes prior to the accident. No flight plan had been filed.
Flight History
The helicopter was being used to provide rides at the Heber Valley Chapter of the Experimental Aircraft Association fly-in. Earlier that day, another pilot had conducted preflight inspections and fuel measurements using a wooden calibration stick. He reported that the helicopter had 29 to 30 gallons of fuel onboard initially. After flying several tours, the pilot and the owner added 10 gallons of fuel. Later, after more flights, the first pilot measured the fuel level with the engine running and rotor blades turning, finding approximately 8 gallons remaining. He informed the accident pilot of the fuel status and that the next tour was for 12 minutes. The accident pilot then departed with two passengers, a mother and her 14-year-old son.
During the flight, the pilot heard and felt a change in engine operation while flying west returning to the airport. He performed a turning 180-degree autorotation toward an open field. Witnesses reported hearing the engine sputter or pop, and observing the main rotor blades slow down. The helicopter's nose dropped, and it turned left, descending rapidly until ground impact. The helicopter came to rest on its right side.
Aircraft and Engine Information
The Enstrom 280FX, manufactured in 1987, is a single-engine helicopter with a three-bladed main rotor and a two-bladed tail rotor. It was powered by a Lycoming HIO-360-F1AD engine. The helicopter had two interconnected 21-gallon fuel tanks with a total usable fuel quantity of 40 gallons. The fuel quantity gauge in the cockpit read in pounds. The helicopter had been manufactured with individual seat belts and shoulder restraints for three occupants, as well as an intercom system. However, the doors were not installed at the time of the accident.
Post-Accident Examination
Examination of the wreckage revealed that the engine was not running at impact, as evidenced by a cooling fan blade forced through the shroud. Rotational continuity was established, and compression was noted in all cylinders. No pre-impact mechanical anomalies were found in the airframe or engine. The fuel system contained minimal fuel; the gascolator held about 2.2 fluid ounces. The caution/warning annunciator panel was examined, but none of the light bulbs exhibited stretched filaments, though vertical impact loads may have been insufficient to cause stretching.
Injuries and Restraint System
The pilot and both passengers were seriously injured. The mother in the center seat suffered a nearly severed left foot and spinal compression fractures. The 14-year-old son in the right seat sustained numerous fractures, brain and torso hematomas, and severe internal injuries. The center seat was equipped with a single-strap shoulder harness, but the buckle portion was missing. The left seat's harness was found unbuckled. First responders had cut the straps in multiple places.