WPR25FA100

The pilot and passenger were maneuvering the helicopter at a low altitude over a frozen reservoir while searching for wildlife. The pilot occupied the front right seat, and the passenger was in the rear cabin area, secured with a harness. The passenger saw the power distribution lines about the same time that the pilot attempted to maneuver to avoid them. The helicopter’s main rotor blades then impacted one of the three lower phase power lines, and the helicopter subsequently descended to the frozen reservoir. The helicopter's rate of descent was likely slowed by the impacted power line, which prevented it from going through the ice. The passenger estimated that the helicopter free-fell only 30 ft, although the phase lines were about 160 ft above the reservoir surface. Impact with the ice resulted in substantial damage to the fuselage, main rotor, and empennage. Examination of the helicopter revealed no pre-accident mechanical malfunctions or failures that would have precluded normal operation. The power lines were depicted on the visual flight rules (VFR) sectional aeronautical chart for the area. Although the investigation was unable to determine the extent of the preflight planning performed by the pilot, a thorough review of the airspace prior to conducting the low-altitude flight likely would have made the pilot aware of the power lines’ location and allowed the pilot to maintain clearance from them.

A review of the FAA Salt Lake City VFR sectional aeronautical chart revealed that it depicted the Ririe Reservoir and the accident power lines. Figure 4. Excerpt of Salt Lake City VFR sectional chart showing power lines crossing the Ririe Reservoir (highlighted with yellow circle) (Source: FAA). According to section 11.3.2 (Unlighted Catenary Markers) of FAA Advisory Circular (AC) 70/7640-1M (Obstruction Marking and Lighting), catenary markers “should be mounted on the highest catenary line.” Section 11.3.2.2.3 (Wire Sag) of the AC further states that “the maximum sag distance between the line holding the unlighted markers and the next lowest catenary wire should be no more than 25 feet (7.62 m), and it should not violate the sag requirements of the transmission line design.” On February 20, 2025, about 1631 mountain standard time, a Bell Helicopter Textron Canada 505 helicopter, N118LG, was substantially damaged when it was involved in an accident near Ririe, Idaho. The pilot was fatally injured, and the passenger was seriously injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the passenger, he and the pilot had hunted with the helicopter on a previous flight and departed Rexburg-Madison County Airport (RXE), Rexburg, Idaho, intending to overfly the Ririe Reservoir to video a large herd of elk. The pilot was in the front right seat, and the passenger was in the rear cabin area, secured with a harness. The passenger reported that neither he nor the pilot saw the power lines that spanned the frozen reservoir until the helicopter was immediately in front of the power lines. The pilot attempted to “dive underneath” the power lines; however, the main rotor blades struck a power line, and the helicopter subsequently impacted the frozen reservoir (see figure 1). The passenger recalled that the power line must have arrested the fall, because the helicopter only free fell about 30 ft. The passenger stated that he exited unassisted and that the engine was still running after the accident and later shut down on its own. Figure 1. Helicopter wreckage on the frozen reservoir and power lines with two visibility marker balls (highlighted with yellow circles). A witness, who was near the reservoir, reported he saw a black helicopter travelling from the dam [north to south]. He lost sight of the helicopter then heard a “twang sound and a bang.” The witness drove his snow machine to where he could see the black helicopter on the frozen reservoir. He called 911 and assisted the passenger in providing aid to the pilot. A set of power distribution lines (two upper static lines, and three lower phase lines) were located about 188 ft north of the main wreckage. According to a representative of Bonneville Power, the power lines were known as the Swan Valley to Goshen line and crossed the reservoir in an east–west direction. The static wires were about 230 ft above the ice, and the phase lines wereabout 160 ft above the ice. The phase lines were about 1 inch in diameter and were comprised of steel cable with an aluminum outer wrap. Figure 2 illustrates the location of the Swan Valley to Goshen line. Figure 2. Location of the helicopter wreckage and the estimated location of the power distribution lines. Postaccident examination revealed that the two static lines were equipped with orange visibility marker balls, and the lower phase lines were not. One of the three lower phase lines was found fractured and had fallen to the frozen surface of the reservoir. ADS-B data and onboard GPS data showed the helicopter departed RXE about 1618. The helicopter proceeded directly to the Ririe Reservoir dam, crossed the dam about 133 ft above ground level (agl), and continued to the southeast over the reservoir. The last ADS-B data point recorded the helicopter over the reservoir, about 214 ft agl, heading southeast, and about 1.9 miles north of the accident site. The last GPS data point recorded the helicopter adjacent to the power lines at an altitude of about 5,228 ft mean sea level (msl), or about 114 ft agl, and about 49 kts ground speed. An autopsy of the pilot was conducted by the Bonneville County Coroner’s Office, Idaho Falls, Idaho. The cause of death was determined to be traumatic blunt force injuries due to a helicopter crash. The helicopter came to rest on the frozen reservoir on a heading of about 195° magnetic at an elevation of about 5,106 ft msl. The fuselage exhibited crush damage that was consistent with impacting the ice. Both main rotor blades exhibited impact striations consistent with contact by a multi-strand cable. Data downloaded from the engine’s digital electronic control unit revealed nominal power delivery until the final moments of the flight. Postaccident examination of the helicopter revealed no pre-accident mechanical malfunctions or failures that would have precluded normal operation.