On May 5, 2001, approximately 0730 Pacific daylight time, a Cessna U206F, N35854, registered to the pilot and operated by Spence Air Service as a 14 CFR Part 135 on demand air taxi, nosed over during the landing roll at a private airstrip located about 13 nautical miles northeast of Imnaha, Oregon. Visual meteorological conditions prevailed at the time and a company visual flight plan was in effect. The aircraft was substantially damaged and the commercial pilot and his passenger were not injured. The flight departed from Enterprise, Oregon, about 30 minutes prior to the accident. During a telephone interview and subsequent written statement, the pilot reported that he circled the airstrip located in a canyon about three or four times to determine the wind direction. The pilot then set-up for an approach to the southeast (120 degrees). During the approach, the wind sock was limp, however, shortly after touchdown, a strong gust of wind picked the aircraft up then dropped it down. The pilot opted to continue the landing instead of going around. Due to insufficient room to stop before running off the airstrip, the pilot intentionally tried to ground loop the aircraft. The nose gear separated and the aircraft nosed over, coming to rest inverted The pilot reported the wind was from the northeast at two knots, gusting to 20 plus knots. Moderate turbulence was reported in the area and on final approach. The Pittsburg Landing strip is a remote backcountry strip surrounded by rising terrain. The strip is 1,050 feet in length and 75 feet wide. The elevation is 1,500 feet mean sea level. The surface is rough and sod covered. A windsock is located on the field. Landing recommendations are to approach from the north and land to the south.