Accident Overview
On November 2, 2018, about 1130 central daylight time, a Bell 47G-3B-1 helicopter, registration N1159W, was destroyed in an accident near Wichita Falls, Texas. The pilot sustained minor injuries, and the certified flight instructor (CFI) sustained serious injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Flight Details
The pilot reported that the flight was intended to practice emergency procedures with the CFI. After completing four uneventful autorotations, the helicopter climbed to an altitude of about 1,500 feet mean sea level and entered the final approach leg of the traffic pattern to conduct a 'hydraulics off' approach. While established on final approach, the CFI reached down to turn off the hydraulic switch, at which point the engine lost complete power. The pilot immediately transferred flight controls to the CFI, who prepared for an autorotation in a nearby field. During the descent, the helicopter struck powerlines before landing hard. The main rotor blade severed the tailboom, and the helicopter spun before coming to rest on its side.
Postaccident Examination
A mechanic and a Federal Aviation Administration inspector examined the wreckage. No anomalies were found with the engine that would have precluded normal operations. The spark plugs appeared consistent with normal operation. The engine rotated smoothly, valves moved freely, thumb compression was established, and spark was obtained from the magnetos. The engine controls remained attached to the carburetor, with the mixture locked to the full rich position and carburetor heat off. Disassembly of the carburetor revealed no anomalies. The fuel strainer and oil filter were clear of debris. The ignition switch was found in the BOTH position at the accident site.
The instrument panel was removed and electrical wires examined; no abnormalities were noted. The ignition switch positions (RIGHT, LEFT, and BOTH) were tested and functioned normally. However, when the key was in the LEFT or RIGHT position, a movement of the key would temporarily ground the switch. It was noted that a long keychain attached to the key extended over the hydraulics switch when the key was in the ignition.