On November 18, 1997, about 1500 eastern standard time, a Naval Aircraft Factory N3N-3, N45018, registered to a private individual, nosed over during the landing roll at the Avery County/Morrison Field Airport, Spruce Pine, North Carolina. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 personal flight. The airplane was substantially damaged and the commercial-rated pilot, the sole occupant, was not injured. The flight originated about 1425, from the Greeneville Municipal Airport, Greeneville, Tennessee. The pilot stated that on final approach he was 20 mph fast and the airplane was landed past the first 1/3 portion of the 3,000-foot asphalt runway. He applied the brakes, but the left brake locked up and the airplane veered off the left side of the runway and nosed over. The airplane was uprighted and when attempting to tow the airplane, the left brake remained engaged. Postaccident examination of the right brake revealed the brake/rotor clearance was measured to be at two places .011 and .020 inch. The adjustment limits are .008-.010. No determination was made as to the reason for the malfunction of the left brake.