On August 15, 1993, at 1005 Pacific daylight time, a Hughes 369D helicopter, N8606F, experienced an inflight loss of control and crashed during an attempted auto rotation near Chico, California. The helicopter was rented by the Butte County Sheriff's Department from P. J. Helicopters of Red Bluff, California, and was on an aerial observation flight. Visual meteorological conditions prevailed at the time and no flight plan was filed for the operation. The helicopter sustained substantial damage. The certificated commercial pilot incurred minor injuries and the observer was not injured. The flight originated at the Ranchero Airport, Chico, California, on the day of the mishap at 1000 hours as a police aerial observation mission. In his written and oral reports, the pilot, who is a Butte County Sheriff's lieutenant, stated that the department rents this particular helicopter on an as needed hourly basis for surveillance and search rescue missions. All four doors are removed from the helicopter for the surveillance missions. The pilot said that he had just departed from the Ranchero Airport and had achieved a cruise altitude of 500 feet AGL when he heard a loud bang and felt a severe vibration throughout the airframe. The pilot stated that he entered a 180 degree auto rotation to a clear area in an almond orchard with power. During the landing flare, the pilot observed that the helicopter began to spin to the right when he applied pitch input to the collective. He said that he immediately rolled off the power and the helicopter collided with the ground, then rolled over. A ground witness reported observing the accident sequence. He stated that he observed the helicopter fly toward his location, then when it was nearly overhead, saw a cloth like object come out of the helicopter and fly back toward the tail. Shortly thereafter, the witness observed the helicopter descend rapidly as it turned 180 degrees until it disappeared behind the trees. In his statement, the pilot reported that he flew to the Ranchero Airport to pick up his observer. The pilot said he had flown with the same individual the day before and had loaned him a nomex flight suit to wear. The pilot noted that when he landed, the observer was waiting on the taxiway and he did not shut down the helicopter. The observer walked to the helicopter then went to the rear compartment for a moment before climbing in the right front seat. The pilot reported that the day after the accident he found out that the observer had worn his own nomex flight suit and had placed the borrowed one under some bags tied down in the rear compartment. Subsequent examination of the helicopter and the accident site revealed that the flight suit was unaccounted for and could not be located. The pilot said that several days after the accident a search party from the Sheriff's department located a shredded nomex flight suit in the orchard. The location of the flight suit was described as not far from the accident site and back along the direction of the helicopter's flight path.