On October 18, 1997, at 1700 central daylight time, a Piper J3L-65, NC-33252, operated by a private pilot, was substantially damaged when the airplane overran the runway on landing and struck trees at a private airstrip, near Reeseville, Wisconsin. The pilot reported no injuries. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under 14 CFR Part 91 and no flight plan was on file. The flight departed Hartford Municipal Airport at 1545 cdt. In an interview, the pilot said that at the time of the accident, the winds were from the southwest at 10 knots. He entered the traffic pattern on a left downwind for a northbound landing on his private airstrip. The pilot reported that he landed approximately one-third of the way down the 900' grass strip. During the roll out, he depressed the brake pedals and found both to be ineffective in slowing the airplane. He said that because of trees off the departure end of the runway, a go-around attempt would have been inappropriate. He opted to continue the landing roll, swerving to the left before colliding with trees off the departure end of the runway. Examination of the wreckage by the Federal Aviation Administration (FAA) and the National Transportation Safety Board (NTSB) revealed substantial damage to the right wing, which had separated from the airframe. The right wing leading edge, approximately four feet outboard of the wing root, revealed chordwise crushing. The brakes pedals were depressed and it was confirmed that there was no brake engagement at either wheel. Examination of the brake system by the FAA revealed that upon removal of the main wheels, the brake expander tubes on both wheels were found to be hardened and stiff. Further investigation revealed that the master cylinder reservoir was not full. After adding approximately 1\2 ounce of brake fluid to the reservoir, the brakes engaged. In November 1996, the airplane underwent its most recent annual inspection. An aircraft log entry dated November 19, 1996, indicates that the brake master cylinders were checked and serviced. The pilot said that three flights prior to the accident, on September 13, 1997, the brakes felt 'soft' following a landing at Hartford Airport. At a Fixed Base Operation (FBO) on the field, the pilot asked the maintenance department to check the brakes. He said that the maintenance facility indicated to him that the brakes were tested, no anomalies were found, and that no work had been done to the airplane. There was no entry made in the aircraft logbook reflecting any service work being done. The pilot said that he flew the accident airplane twice after the brakes were tested by the maintenance facility, prior to the accident flight. The pilot stated that he did not recall ever using or testing the brakes at any time during this time. He said that he usually only uses the brakes after landing at Reeseville, due to the short landing area.