On May 22, 2002, about 0850 mountain standard time, a Cessna 206, N5050U, lost directional control, veered off the runway, and nosed over while attempting to land at Eagle Airpark (A09), Mohave Valley, Arizona. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The private pilot, the sole occupant, was not injured; the airplane sustained substantial damaged. Day visual meteorological conditions prevailed, and a flight plan had not been filed. The personal cross-country flight originated from North Las Vegas Airport (VGT), Las Vegas, Nevada, about 0750 Pacific daylight time, with a planned destination of A09. In a written statement, the pilot reported that during his preflight inspection he discovered the nose strut was completely flat. A mechanic inflated the strut with nitrogen gas and measured the chrome to ensure proper inflation. The pilot noted that the exposure of the chrome appeared to be above average, but during taxi and takeoff he did not feel any steering abnormalities. After about an hour en route, the pilot arrived at A09 and made a normal approach to runway 35. During touchdown, the nose wheel made contact with the runway and would not respond to control inputs. The locked nose wheel began to drift to the left of centerline, and the pilot applied full right rudder to counteract the drift. After the airplane still did not respond, he applied full brake pressure in an attempt to stop before departing the runway. The airplane continued off the runway and encountered a soft, dirt field, resulting in the nose landing gear sinking in. The airplane nosed over and came to rest inverted. The airplane incurred damage to both wings and the tail. During a telephone interview with the National Transportation Safety Board investigator-in-charge (IIC), the maintenance facility that serviced the airplane reported that the pilot was involved in an incident about a year before the accident. During an attempt to land, the pilot came down in a nose low attitude, resulting in a propeller strike and right wing damage. The maintenance facility completely serviced the airplane, and, amongst other maintenance, they completely took apart the nose strut and rebuilt it. The pilot flew the airplane after the servicing, and later complained of the nose gear sticking. He said that while landing the nose strut would occasionally lock, making him unable to steer the airplane unless he applied brake pressure. When that occurred, he would steer with the brakes in an effort to maintain directional control on the runway and taxiways. Again, the maintenance facility completely took all components of the nose strut apart, cleaned and inspected them, finding nothing noticeably wrong with the airplane. The pilot flew it again, and complained of the same locked nose strut problem. The same cycle happened again, and the maintenance facility told the pilot that he needed to get a new strut. They thought that the strut the airplane was equipped with, was not repairable. They had determined that regardless if the strut was under or over serviced, it would inevitably stick. The pilot refused the recommendation of the maintenance facility to have the strut replaced. The maintenance facility stated that the day of the accident a mechanic had inflated the nose strut upon the request of the pilot. When inflating struts, they monitor the nitrogen pressure and measure the chrome exposure dimension to aircraft specifications. After establishing that the strut is at the correct inflation level they will bounce it up and down to test it. The maintenance facility reported that on the day of the accident the nose strut was well within Cessna specifications after they serviced it. During a telephone interview with the IIC, a certified flight instructor that flew with the pilot stated that the pilot had difficulties landing the airplane. After the pilot was involved in the incident resulting in a propeller strike, they spent about 10 hours practicing landings. On several occasions he had bounced the airplane down the runway and let the airplane get away from him.