History of Flight
On August 14, 2011, at about 1245 Pacific daylight time, a Bell Helicopter 47G-3B-2 Soloy, registration N475AL, impacted trees following a loss of lift near Los Banos, California. Double Springs Helicopters conducted the flight under 14 Code of Federal Regulations Part 137 for agricultural operations. The commercial pilot was not injured. The helicopter experienced substantial damage to the tailboom and main rotor blades. The agricultural flight had just departed from the tender truck at approximately 1245. Visual meteorological conditions prevailed, and no flight plan was filed.
According to the pilot, immediately after takeoff from the elevated landing pad on top of the tender truck, he observed a decay in rotor rpm. He attempted to recover the rpm by lowering the collective, but the rpm did not recover. Due to the low altitude, he was forced to land into an almond grove.
Examination Findings
The helicopter was recovered from the accident site for further examination. On August 18, 2011, the helicopter and engine were inspected at the operator’s facility. Investigators found no evidence of pre-impact abnormalities with the flight controls. The engine exhibited impact damage to the fuel control unit, resulting in a fuel leak from the control arm shaft. No other mechanical abnormalities that would have precluded normal operation were noted.
The compressor stator vanes were heavily contaminated with what appeared to be an agricultural product. A representative of the engine manufacturer indicated that compressor rinses should be performed more frequently when the engine operates in a corrosive environment, such as agricultural operations.
Additionally, the main rotor blades were contaminated with an unknown agricultural product. The entire surfaces of both blades were covered with a frosted layer of an unknown material, described as having the consistency of peanut butter.