On September 25, 1994, at 1530 Pacific daylight time, a Piper PA-28-140E, N4813T, sustained substantial damage during a hard landing at Woodland, California. The aircraft was owned and operated by the pilot. The certificated flight instructor on board was conducting a biennial flight review. Visual meteorological conditions existed at the time and no flight plan had been filed for the operation. Neither of the certificated pilots were injured. The flight originated from Nut Tree airport at 1400 on the day of the accident. The flight instructor reported that the pilot was attempting a full flap, short field approach to runway 16 at Yolo County airport. During the approach, their airspeed became "too slow" and they "lost lift." The aircraft landed hard about 20 feet short of the runway threshold. After touchdown, the landing gear struck a berm which preceded the runway threshold. The aircraft slid to a stop on the runway numbers. The pilot who was on the controls reported that he had initiated the approach from the traffic pattern, turning final about 1/2 mile from the approach end of the runway. He stated that he was on a stabilized approach at what he estimated to be less than a 3-degree descent angle. He reported his altitude and airspeed at the completion of his turn to final as 600 feet agl and 70 knots. He said he was maintaining a power setting of between 1,700 and 1,900 rpms which gave him a vertical descent rate of between 400 and 500 fpm and that he had fully lowered his flaps by the time his altitude reached 300 feet agl. He described the approach as proceeding as planned until the aircraft was about 40 feet above ground level and about 200 feet short of the runway. At this point in the approach, he said the aircraft encountered a "thermal" and the descent rate suddenly increased. He said that he added power to between 2,100 and 2,200 rpms, but that the aircraft continued to sink and he was unable to stop the descent. He reported his airspeed decreased to between 66 to 67 knots during his attempted recovery. He stated that winds remained calm during the approach. A postaccident inspection by a Federal Aviation Administration (FAA) airworthiness inspector revealed that the landing gear was sheared and collapsed, an engine mount was fractured, and the propeller blades were bent.