On July 5, 1999, about 1510 hours Pacific daylight time, a Cessna 177RG, N2175Q, operated by the private pilot, was substantially damaged during a collision with terrain in the takeoff initial climb at Quincy, California. The pilot and two passengers received minor injuries. Visual meteorological conditions prevailed for the personal flight operating under the provisions of 14 CFR Part 91, and no flight plan was filed. The flight was originating at the time as a cross-country flight to Concord, California. In his written statement, the pilot said he departed on runway 06 and during the initial climb he experienced a downdraft and settled into terrain just beyond the runway end. The Quincy/Gansner airport is located in mountainous terrain at 3,415 feet msl. The runway is 4,100 feet in length with obstruction considerations at both ends. Prior to departure, the pilot questioned a resident flight examiner as to how local pilots made their takeoffs under the current conditions. The examiner recommended runway 06. According to the flight examiner, the wind was estimated to be 7 to 10 mph from the southwest, and the temperature inside the hangar sheltered from the sun read 81 degrees Fahrenheit. He briefed the pilot on the airport conditions and recommended departing on runway 06. He also recommended that he not rotate prematurely. The examiner observed the airplane during the run-up and subsequent departure. He commented that the engine was missing, and said this was probably due to the pilot not leaning the mixture for best power. He said the airplane accelerated very slowly and used most of the runway for takeoff. The wind was still less than 10 mph. After takeoff, about 100 feet agl, he observed the airplane's nose pitch up suddenly, then it became obscured from his view by a tree. The pilot stated that he was 322 pounds under gross weight and within the weight and balance envelope. He calculated the density altitude to be 5,841 feet. The other conditions the pilot noted for the takeoff attempt was a temperature of 86 degrees Fahrenheit and winds from 240 degrees at 6 to 8 knots. According to the pilot, by reference to the performance charts in the Pilot Operating Handbook, he calculated that 2,100 feet of ground roll would be required for takeoff. According to the pilot, during the run-up check, he leaned the mixture for best power and set the flaps to 10 degrees. He taxied to and lined up with the runway centerline. He applied full power and stood on the brakes. The rpm was normal and the engine sounded good. He richened the mixture slightly to see if there was any effect on the engine performance, and there seemed to be none. He was confident that the engine was putting out full power and that he was good to go. The Airport/Facility Directory for Quincy/Gansner under airport remarks states, "CAUTION - due to proximity of terrain normal operations are: for departure/touch and go runway 06 only."