On March 13, 2005, about 1704 Eastern Standard Time, a Let model Blanik L-13 glider, N14420, registered to a private individual, was landed hard at the Bob Lee Flight Strip, DeLand, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 instructional flight from Bob Lee Flight Strip, DeLand, Florida. The glider was substantially damaged and the student pilot, the sole occupant, sustained serious injuries. The flight originated about 20 minutes earlier from Bob Lee Flight Strip. The pilot stated he entered downwind at 1,000 feet, selected spoilers and adjusted trim for "lighter stick pressure." He turned base then final, and maintained heading and approach speed down to approximately ten feet, where he felt a sudden "drop in audible airspeed" followed by a rapid descent to impact. Impact was at approximately 45 to 50 degrees nose down. According to a Federal Aviation Administration (FAA) inspector who examined the accident site, interviewed witnesses, and examined the glider, it was observed on final approach at an altitude of approximately 8 feet above ground level, then was observed to "shudder", and abruptly pitch nose down. The glider crashed on the runway approximately 500 feet from the threshold of runway 27. Examination of the flight controls revealed no evidence of pre-impact failure or malfunction. The elevator trim indicator for the rear seat was noted to be full nose-down, which correlated with the trim tab position. A 12-volt battery which powers a variometer was determined to have been installed on the top shelf behind the rear seat and secured by bungee cords. The battery was found approximately 60 feet forward of the where the glider came to rest. According to a representative from the glider manufacturer, the "... classic (heavy) land-acid battery, which had a fixed attachment in the bottom part of the baggage compartment on frame No. 5" is the proper battery installation location. Additionally, installation of the battery by the glider manufacturer is performed "through proper elements (brackets, bolts, etc.) in accordance with airworthiness regulations requirements with regard [to] prescribed emergency load factors." The glider manufacturer does not recommend using "rubber strip" material to secure the battery.