On September 13, 2005, about 1512 central daylight time, a Cessna 172M, N901NS, registered to and operated by Reliance Aviation LLC, as a Title 14 CFR Part 91 flight, crashed in Ocean Springs, Mississippi. Visual meteorological conditions prevailed, and no flight plan was filed. The commercial-rated pilot received serious injuries, and the airplane incurred substantial damage. The flight originated in Milton, Florida, the same day, about 1300. The pilot stated that he had no recollection of the flight leading up to the accident, preparations for the flight, and portions of the day prior to the accident including up to 15 days beyond the day of the accident, however he stated that another pilot who was conducting similar survey flight operations near his location heard the radio communications, and saw the accident take place. The other pilot/witness stated that he was also a contract pilot working for the same survey company, Pictometry Inc., and he was conducting aerial surveys and was piloting his airplane at the time, and he observed events and heard radio communications during and after the accident. He said it was about mid-afternoon, and he and the accident pilot were talking on the working frequency while both conducting their respective survey flights, and during the conversation the accident pilot said that his airplane's engine stared running rough. About 20 seconds later the witness said he heard a "mayday" call on the radio, and that the accident pilot said that his airplane's engine had ceased operating, and he was going down. The witness said that they had both been at 3,000 feet , and he heard "ATC" give the pilot a vector for Ocean Springs, Mississippi, but stated that because of the hurricane related response activities, the accident pilot could not land there. The witness stated that it was at that time that he first sighted the accident airplane, and it was at an altitude of about 800 feet. He said he saw the accident pilot divert to an open field where "track" homes were being built, observed him set up for a left downwind, and then saw the pilot "crank" the airplane around in a tight turn. He said he then realized that the accident pilot was attempting to avoid power lines. The witness said he saw the airplane hit the ground in a spin, left nose down, and coming to an immediate stop. On September 14, 2005, an FAA inspector responded to the accident scene and conducted a postcrash examination. According to the inspector, shortly after the accident occurred, a representative with Ferguson-Harbour Incorporated, an environmental company, was on hand and defueled the accident airplane due to the potential safety hazard, removing about 10 to 15 gallons of fuel from the right wing. There was no fuel in the left wing. The inspector further stated that the fuel selector had been set to the left tank position, and there was no evidence of significant fuel spillage at the scene. On September 19, and 20, 2005, the FAA inspector along with technical representatives from Cessna Aircraft Company, and Textron Lycoming Engines, performed detailed examinations of the airplane and its systems. The detailed examination of the fuel selector valve revealed that it had been set to the left position. No other significant preaccident anomalies were noted to exist with the airplane or any of its systems.