Overview
On September 20, 2015, about 1900 eastern daylight time, a Bell 206L-1 helicopter, registration N165BH, was destroyed during a collision with a ground vehicle and terrain following a flight control malfunction and subsequent loss of control. The accident occurred near Thomaston, Georgia. The commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local aerial application flight, which was conducted under 14 Code of Federal Regulations Part 137.
Flight Details
The pilot stated that the purpose of the flight was to establish spray patterns and flow rates and to calibrate the GPS and spray equipment for a contracted job. He departed from a platform-equipped "mix" truck about 10 minutes before the accident and returned to land on the truck to clean the helicopter's windscreen. During a right pedal turn to land on the truck, just before touchdown, a pin connecting a push-pull tube to the left anti-torque pedal broke, resulting in a loss of directional control. The pilot maneuvered away from the truck to avoid striking employees and attempted to land back on the truck's platform unsuccessfully. He repositioned away from the truck, closed the throttle, and lowered the collective to land, causing the main rotor blades to strike the side of the truck.
Pilot Information
The pilot held a commercial pilot certificate with ratings for airplane multi-engine land and rotorcraft/helicopter. His most recent second-class Federal Aviation Administration (FAA) medical certificate was issued on July 2, 2015. He reported 11,409 total hours of flight experience, of which 40 hours were in the accident helicopter make and model.
Aircraft Information
The helicopter was manufactured in 1979. At the time of the accident, it had been operated for about 16 hours since its most recent annual inspection was completed on September 7, 2015, at 7,977.2 total aircraft hours. The helicopter was equipped with a left-hand "command" kit, and the pilot was flying from the left seat. Additionally, it was equipped with a tail rotor pedal lockout kit, designed to disconnect and lockout the tail rotor pedals at the copilot's seat to prevent passenger interference. In this make and model, the left seat would typically be the copilot's seat, but the left-hand command kit designated the right seat as the copilot's seat. The lockout kit, manufactured by Aeronautical Accessories and installed per supplemental type certificate SR00513AT, could be set to "Lockout" mode to prevent pedal use or "Engaged" mode for pedal control.
Mechanical Findings
Examination of photographs provided by the operator showed that the main transmission and engine were torn from their mounts, and the aft fuselage was destroyed. The tail boom separated just aft of its mount. Photographs of the tail rotor pedal assembly revealed that the left expandable pin, a part of the tail rotor pedal lockout kit, had fractured and disconnected from the left anti-torque pedal to the tail rotor control system. The expandable pin connecting the right pedal to the tail rotor control system remained intact and engaged.
Investigation Notes
The operator shipped the fractured pin by commercial carrier to the NTSB Eastern Region Headquarters for further examination but mislabeled the package with the wrong street address. The package was shipped to a delivery center in Vienna, Virginia, then redirected to San Francisco, California, where it was lost. Consequently, fracture analysis on the pin could not be performed. Photographs of the fracture were not of sufficient quality for visual fracture analysis.
The pilot/operator suggested that the accident could have been prevented if the lockout kit were not authorized for use concurrent with the left-hand command kit.
A review of the design and materials of the expandable pin by the FAA Aircraft Certification Office and the kit manufacturer revealed that the pins were designed to replace "original bolts and are stressed as such." The kit's instructions for continued airworthiness mandated both daily and 300-hour interval inspections for condition and security of the pins.