On June 1, 1996, at 2100 eastern daylight time, a Brantly B2B helicopter, N2261U, sustained substantial damage when it collided with terrain during a forced landing near Oakwood, Ohio. The certificated private pilot/helicopter owner received minor injuries and the one passenger sustained serious injuries. Visual meteorological conditions prevailed at the time of the accident, no flight plan was filed. The flight operated under 14 CFR Part 91. The helicopter departed private property adjacent to the accident site for a local orientation flight, exact time unknown. The pilot reported that while he maneuvered during the approach to land, the helicopter experienced a total loss of engine power. The pilot said that when the power loss occurred, he "...nosed down and put the collective down..." to enter autorotation. He stated that when he attempted to enter autorotation the helicopter was at "...200-300 feet at around 40 MPH." He reported that he "...picked a spot [for landing]... looked at the rotor RPM (RRPM), it was 320...[and] at 60 to 80 feet I pulled collective..." to begin deceleration. The pilot said that the helicopter struck the ground with a forward speed of 30 MPH with the tail skid striking the ground prior to the main gear. According to the pilot, the normal operating range for RRPM is 400-472 and that 400 RRPM was minimum for autorotation. While discussing the attempted autorotation, the pilot said: "Normally, the rotor will speed up when you bring collective in." The response to an engine power loss at altitude is described in a United States Army Training Circular as follows: "Upon detecting engine failure, the [pilot] will lower the collective to maintain rotor RPM within limits while adjusting the pedals to trim the aircraft. He will select a suitable landing area and, using turns and adjusting airspeed as necessary, maneuver the aircraft for a safe landing to the intended landing area. At approximately 100 feet AGL, apply aft cyclic to initiate a smooth, progressive deceleration. Maintain aircraft alignment with the touchdown area by properly adjusting the pedals and cyclic. Adjust the collective as necessary to prevent excessive rotor RPM. At approximately 15 feet AGL, apply sufficient collective to control the rate of descent and ground speed. Adjust the cyclic to attain a landing attitude, and apply collective as necessary just prior to touchdown to cushion the landing." Excerpts from the referenced publication (United States Army Training Circular No. 1-211: Aircrew Training Manual Utility Helicopter p. 6-76, 9 December 1992) are appended. The pilot reported that he "...lost fuel pressure which resulted in engine failure." A postaccident inspection of the aircraft and its records by a Federal Aviation Administration (FAA) Aviation Safety Inspector revealed that the fuel overboard vent tube assembly was clogged. The FAA Inspector stated: "Cutting open the tube near the open overboard vent end...resulted in finding insect and nest remains that filled the tube. The vent tube was plugged in at least two places and a third plugged location was not opened up for examination." The examination of the aircraft records revealed that the most recent documented 100 hour inspection was accomplished on May 18, 1970. The pilot reported that he did not possess a helicopter rating, and that he had received "...5 to 6 hours..." of instruction in helicopters. According to the Ohio State Highway Patrol Aircraft Crash Record, the pilot reported that he had flown 28 hours within the preceding six months, including about 3 hours in the accident aircraft.