On September 23, 2004, at 1050 Pacific daylight time, a Piper PA-28, N56775, sustained substantial damage during the landing rollout at the Crane Island Airstrip, located 2 nautical miles south of Deer Harbor, Washington. The airplane is owned by the pilot, and was being operated under the provisions of 14 CFR Part 91. The private pilot and his sole passenger were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight. The flight departed Lopez Island (S31), Lopez, Washington, approximately 20 minutes prior to the accident. In a written report dated September 23 2004, and in a telephone interview with the NTSB investigator-in-charge, the pilot reported that he made two low approaches over the 1,500 foot runway prior to landing. The pilot related that on the third approach the landing was made, and that during the rollout he found the brakes were having little or not effect in slowing the aircraft. The pilot stated the plane left the runway going straight ahead at approximately 15 to 25 miles per hour. The pilot further stated the airplane rolled down an embankment at the southeast end of the runway before coming to a stop in an upright position. The pilot reported that after exiting the airplane and inspecting the runway surface, he found the grass runway surface to have been cut very short and to be very wet. The pilot stated that he felt the short, wet grass airstrip surface was the major reason he was unable to stop the airplane. The pilot reported the right wing, engine mount, and firewall had sustained substantial damage, and that he hadn't experienced any mechanical difficulties or malfunctions with the airplane that would have contributed to the accident.