On June 1, 1996, at approximately 1500 Pacific daylight time, a Cessna 120, N2965N, sustained substantial damage when it nosed over during an aborted takeoff at Tieton State Airport near Rimrock, Washington. The private pilot received a minor injury; his single passenger was uninjured. Visual meteorological conditions prevailed and no flight plan was filed for the 14 CFR 91 local flight. The pilot was attempting to take off on runway 20, which according to the U.S. Government Airport/Facility Directory (A/FD) is a 2,471 by 140 foot turf runway with a rough surface. The airport elevation is 2,961 feet above sea level. The pilot reported that the takeoff proceeded normally until the airplane reached an indicated airspeed of 40 to 45 MPH, but that "after that the indicated airspeed didn't increase." He reported what happened during the rest of the accident sequence as follows: After landing and taking off about 30 or 40 times from this strip, and in this airplane, over the last five or six years, I knew where I should be developing lift and able to get the mains off the rough ground and build airspeed in ground effect. This was not happening. Even though the airspeed indicator had not risen over about 40 or 45 I was still attempted [sic] to ease the yoke back and see if the airplane wanted to fly....The plane still did not want to lift into ground effect. Based on previous experience I should have had the plane developing lift before the camp ground [just beyond midfield according to a hand-drawn sketch furnished with the pilot's statement.] When I passed the camp ground, went a little further and still was not developing lift, I pulled all the power...and started applying the [brakes]. I eased back on the yoke lowering the tail to the ground and then continued to hold the yoke in my gut while applying brakes. As we slowed I applied more brakes....The tail rose and I saw the nose go down as we nosed over the front and came to rest upside down...approximately 200 [feet] from the end of the strip. The pilot reported the weather at the airport as clear, 30 miles visibility, temperature 72 degrees F, and altimeter setting 30.80 inches Hg, with no precipitation or restrictions to visibility. He stated in his narrative that the wind sock at the top of the field "was hanging limp at the time I launched." Based on the reported temperature and altimeter setting and the field elevation, density altitude was computed by the investigator to be 3,424 feet. The FAA investigator assigned to the accident, an operations air safety inspector from the Flight Standards District Office at Renton, Washington, furnished a post-accident weight and balance computation which indicated (based on weight and balance data in the aircraft records, and fuel and occupant loading reported by the pilot) that the aircraft's gross weight at the time of the accident was 32 pounds over its maximum gross weight (1,482 pounds actual versus 1,450 pounds maximum.) The pilot made the following recommendations on his accident report as to how the accident could have been prevented: "(1) greater power (2) less weight (3) abort sooner (4) go easier on the brakes as airplane slows." The A/FD and the Pilot's Guide to Washington Airports (published by the Washington State Department of Transportation Aeronautics Division, which also maintains the unattended airport) both indicate that Tieton State Airport is closed from October 1 through June 1. The A/FD contains an instruction to contact the state Aeronautics Division prior to use of the airport.