On May 19, 1994, about 0720 hours Pacific daylight time, a Robinson R22-B helicopter, N140PH, collided with a second Robinson R22-B, N2314Z, while on the ground at a private airstrip, about 10 miles north of Stockton, California. The two helicopters were being operated as a visual flight rules (VFR) flight to dry cherry trees in the local area when the accident occurred. The helicopters, operated by Sunrise Helicopters Inc., Stockton, California, both received substantial damage. The pilot of N140PH, a certificated commercial pilot, received minor injuries. The pilot of N2314Z, also a certificated commercial pilot, was not injured. Visual meteorological conditions prevailed. The flight originated at Stockton Metropolitan Airport, about 0540 hours. The pilots reported that after terminating the tree drying operation over a local orchard, both aircraft proceeded to Wallom Field, a private airstrip, to refuel. The pilot of N140PH landed near the refueling point and had reduced the engine power to idle. The rotor blades were still turning. The pilot of N2314Z landed to the right side of the first aircraft. After the landing gear skids had touched down, the pilot lowered the collective pitch control to full down. As the second helicopter's rotor blades reached flat pitch, they meshed with those of N140PH. The resulting action caused both helicopters to pivot on the ground. Both aircraft received damage to the main rotor blades, mast and transmission, and tail boom.