The pilot reported that the brakes functioned normally during taxi, and pretakeoff checks, with no anomalies noted. The flight was uneventful, and he entered the traffic pattern at his destination airport. After touchdown, he retracted the flaps, reduced engine power, and applied the brakes, and the airplane initially decelerated as expected. With about one-third of the runway remaining, total brake pressure was lost. He determined that insufficient runway remained to execute a go-around, so he elected to perform “S” turns in an attempt to slow the airplane. As the airplane approached the end of the runway, he applied right rudder to avoid a runway overrun. During the ensuing turn, the left wing impacted the ground, which resulted in substantial damage to the wing. The mechanic who completed the most recent annual inspection of the airplane reported that, 10 days before the accident, he had installed a new brake booster in accordance with a supplemental type certificate (STC). The STC kit did not include the required “screw-vent”, so the mechanic temporarily installed a brake bleeder valve and instructed the owner not to fly the airplane before the correct screw-vent was installed. The brakes were bled multiple times, operationally checked, the maintenance logbook was signed, and the airplane was returned to service. The pilot reported that, 5 days before the accident, the brakes were inoperative due to a lack of pressure during an attempted taxi. He stated that a local mechanic sanded the brake caliper and replaced the O rings/packing; however, no maintenance logbook entry was made, and the mechanic denied performing the work. The mechanic did report that he had examined the airplane, provided advice to the pilot, and observed several discrepancies, including a missing screw vent. Following the reported maintenance, the pilot stated that an operational check of the brakes was conducted with no anomalies noted. Postaccident examination of the brake system by an FAA airworthiness inspector revealed a significant amount of air in the system and no brake pressure. After the brakes were bled and an operational check was conducted, brake engagement did not occur until the final 10% of brake handle travel, and full brake effectiveness was not achieved. The examination also identified the presence of an unapproved part and incomplete compliance with the supplemental type certificate. Additionally, evidence indicated that undocumented maintenance had been performed following installation of the STC. Due to either an unapproved part, undocumented maintenance, and incomplete compliance with the STC, it is likely that the air in the brake system was a result of inadequate maintenance.