On November 16, 2001, approximately 1500 central standard time, a Beech BE-50 twin engine airplane, N432L, sustained substantial damage during a hard landing at the Altus Mountain Regional Airport (AXS), near Altus, Oklahoma. The aircraft was owned and operated by the pilot under 14 Code of Federal Regulations Part 91. The single-engine land rated private pilot did not receive injuries. Visual meteorological conditions prevailed at Altus; however, the aircraft encountered fog along the planned route and diverted to Altus. The flight originated from Altus Air Force Base. A flight plan was not filed. The pilot reported that during an instrument flight rules (IFR) flight from Poplar Bluff, Missouri, to Slaton, Texas, a fog bank, which extended to the ground, was encountered about 20 nautical miles from Altus, Oklahoma. The pilot elected to land the airplane at AXS, but inadvertently landed at Altus Air Force Base. Subsequently, the aircraft departed the military base and landed at AXS. The FAA inspector, who responded to the accident site, reported that the airplane landed hard, bounced, and departed the runway. Subsequently, the airplane rolled through a ditch, collapsing the nose landing gear. Examination of the airplane by the FAA inspector revealed structural damage to both engine mounts, and the nose landing gear assembly. Additionally, the generator mounting pad for the left engine was damaged, and the propeller blades were bent aft. The hobbs meter reading was 2,383.1 hours. The previous owner of the airplane reported that the airplane had been sold to the pilot approximately 2 weeks prior to the accident. Numerous attempts to obtain a completed Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) from the pilot were unsuccessful.