On July 28, 1995, at 1640 hours Pacific daylight time, a North American AT-6F, N3173L, collided with the runway while landing at Daugherty Field, Long Beach, California. The aircraft sustained substantial damage; however, neither the pilot nor his passenger were injured. The aircraft was being operated as a personal flight by a private owner when the accident occurred. This leg of the flight originated in Porterville, California, at 1506 on the day of the accident. Visual meteorological conditions prevailed at the time and no flight plan had been filed. The aircraft arrived at Long Beach as No. 4 in a flight of four aircraft. The flight passed over Daugherty Field to the west, turning back over the Queen Mary, and then north for an overhead break for landing. The pilot temporarily lost sight of the three other aircraft as they descended on the approach, but regained visual contact after he saw the first two touching down and the third on short final for runway 12. The break had placed the pilot south of the final approach path so he turned back to the north to intercept final. After he rolled out on final he recognized that there was a right crosswind and crabbed into the wind anticipating a crosswind landing. After touchdown, the aircraft veered sharply to the right as the left main landing gear collapsed. After the aircraft contacted the runway it slid off the right side striking an electric runway-taxiway sign with frangible mounts on a .25-inch high concrete base. The pilot stated that at the time aircraft control was lost, he was applying right aileron and left rudder to compensate for the crosswind. The aircraft sustained damage to the left wing tip, left aileron, left wing inboard of the landing light, the left main landing gear, and propeller. An inspection of the aircraft performed by an FAA airworthiness inspector revealed the static pressure of the hydraulic system to be about 1400 psi. The mechanical down lock for the left main landing gear was broken and displaced from its installed position atop the left strut. The left strut was found at a 45-degree angle and was pushed through the wing surface. The mechanical indicator for gear position did not show the left main gear to be in the down and locked position. There was no evidence to show that the down lock had failed while in the "down and locked" position. In a telephone interview, the mechanic who normally maintains the aircraft stated that the bolts attaching the locking mechanism to the main bulkhead in the left wing were backed out approximately 0.25 inches. He said that the displacement of the bolts allowed enough movement in the locking mechanism to prevent it achieving or maintaining a full down and locked position with the left main gear.