N475ALBell 47G-3B-2 · 1968

On August 14, 2011, about 1245 Pacific daylight time (PDT), a Bell Helicopter, 47G-3B-2 Soloy, N475AL, impacted trees following a loss of lift near Los Banos, California. Double Springs Helicopters was operating the helicopter under the provisions of 14 Code of Federal Regulations (CFR) Part 137. The commercial pilot was not injured; the helicopter sustained substantial damage to the tailboom and to the main rotor blades. The agricultural flight had just departed from the tender truck about 1245. Visual meteorological conditions prevailed, and no flight plan had been filed.

The pilot reported that just after takeoff from the elevated landing pad located on top of the tender truck, he observed the rotor rpm decaying. He attempted to regain the rpm by lowering the collective; however, the rpm did not recover, and due to the low altitude operation, he was forced to land into the almond grove.

The helicopter was recovered from the accident site for further examination.

The helicopter and engine were inspected on August 18, 2011, at the operator’s facility. No evidence of pre-impact abnormalities with the helicopter’s flight controls were noted. The engine had impact damage to the fuel control unit, which resulted in a fuel leak from the control arm shaft.

No other mechanical abnormalities were noted that would have precluded normal operation.

It was noted that the compressor stator vanes were very dirty from what appeared to be an agricultural product.

The representative of the engine manufacturer noted that there is a need to complete compressor rinses more frequently when the engine is operated in a corrosive environment such as agricultural operations.

The main rotor blades were noted to be contaminated with a unknown agricultural product. The entire surfaces of both blades were frosted with a layer of an unknown material, which had the consistency of peanut butter.