On May 1, 2016, about 1130 central daylight time, a Cessna 150F, N8619G, experienced a loss of pitch control during landing flare and impacted runway 35 at Ponca City Regional Airport, Ponca City, Oklahoma. The airplane sustained substantial damage to the firewall. The pilot sustained serious injuries and the passenger was uninjured. The airplane was operated by the pilot under 14 Code of Federal Regulations Part 91 as a personal flight that was not operating on a flight plan. Visual meteorological conditions prevailed at the time of the accident. The local flight originated from PNC about 1045. The pilot stated that he performed a "full" preflight inspection of the airplane prior to departing for a pleasure flight. The flight returned without incident for an approach for landing to the airport. During landing flare on runway 35 and about 1-2 feet above runway, the airplane "shot up drastically". The airplane climbed about 10-20 feet, the pilot "gently" applied forward control pressure on the control yoke, and the airplane "instantly" pitched down and impacted the runway. The pilot stated that as he waited for an ambulance, he saw the left elevator was separated from the horizontal stabilizer. An airplane maintenance record entry dated November 9, 2015, shows that an annual inspection had been performed and that the bearing in the elevator bearing crank assembly was "reset" by an airframe and powerplant mechanic with inspection authorization. The airplane accumulated about 25 hours of flight time after the annual inspection. Post-accident examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that a bolt that links the left elevator to the control system was missing. The bolt was found inside the left elevator tip. The FAA Inspector reported that there was an improper reinstallation of the elevator, which resulted in it coming loose.