20080430847369I

(-23) Pilot stated he flew a normal traffic pattern and final approach with flaps at 20 degrees. Pilot stated he performed a gump check and check the landing gear position 3 times. At about 4', over the numbers, he felt the aircraft sink. He added power and flew further down the ruway. About the time he expected to touch down he felt a severe shaking of the aircraft. He pulled back on the control wheel thinking he may have lost a wheel. He then heard and felt a "bam, bam bam" and the prop stopped vertical. The aircraft slid to stop, on its belly, slightly off the right side of the runway at 45 degree angle to the runway heading. Propeller marks on the runway are consistent with the pilot's statement regarding a "severe shaking" and then pulling back on the control wheel and then hearing the "bam, bam, bam." The propeller marks start approximately 2000' from the approach end of the runway and continue for approximately 100' then cease for approximately 20', a reappear and continue, gradually growing fainter. There are no scuff marks on the tires or skid marks on the runway that would indicate an intransient, partially extended (retracted) landing gear. Landing gear was cycled several times. The landing gear operated smoothly, without hesitation and locked into the selected position. Initially the landing gear warning horn did not operate with the landing gear in the up and locked position and the throttle retarded to idle. A mechanic manipulted the mechanism at the throttle body and the warning horn sounded each time the throttle was retarded to idle.