On August 14, 1999, at 1830 central daylight time, an Aviat-Pitts S1-11B biplane, N540DM, was substantially damaged following a loss of control during the landing roll at the Sack-O-Grande Airport near Katy, Texas. The instrument rated commercial pilot, sole occupant of the airplane, was not injured. The airplane was owned and operated by the pilot. Visual meteorological conditions prevailed for the Title 14 CFR Part 91 personal flight for which a flight plan was not filed. The local flight originated approximately 15 minutes prior to the accident. The 1,400-hour pilot reported to the FAA inspector, who traveled to the accident site, that he had been operating in the designated aerobatic box above the airport for approximately 15 minutes. He added that "while recovering from a hammer head stall, the propeller and engine over sped," and suspecting engine damage, he elected to execute a precautionary landing on runway 27. The pilot stated that the airplane touched down about mid-field on the 4,300 foot grass/sod runway. The airplane was decelerating through 40 knots when he applied brakes to exit the runway; however, the left brake failed, and the airplane "made a violent turn to the right." The left wing tip impacted the ground, and the tailwheel-equipped airplane nosed over and came to rest in the inverted position. The pilot was able to exit the biplane without assistance. Examination of the wreckage by the FAA inspector revealed that the rudder and vertical stabilizer were crushed, the fuselage was wrinkled, and the left main landing gear was folded under the fuselage. The inspector verified that the master cylinder for the left brake had failed, and braking was not possible. He added that the 1998 airplane had accumulated a total of 160 hours since new. The pilot reported that an examination of the engine revealed signs that an engine overspeed had occurred, necessitating the replacement of the engine.