THE PILOT OF THE HUGHES 269B ALLOWED ROTOR RPM TO DROP OUT OF THE GREEN ARC, WHILE MANEUVERING OVER AN ORCHARD IN ORDER TO KNOCK HAZELNUTS OFF OF TREES WITH HIS ROTOR WASH. HE WAS UNABLE TO REDUCE COLLECTIVE BECAUSE OF THE TREES, AND HE COULD NOT ACCELERATE ENOUGH TO INCREASE ROTOR SPEED PRIOR TO SETTLING INTO THE ORCHARD. AFTER THE ACCIDENT, THE PILOT STATED THAT HE HAD TAKEN ON A PASSENGER AND FILLED THE AIRCRAFT WITH FUEL, WITHOUT RECOMPUTING THE PERFORMANCE DATA.