On October 1, 2008, at 1502 eastern daylight time, an experimental amateur-built Alisport Silent-IN powered glider, N373DB, was substantially damaged during a forced landing after takeoff from Indian River Aerodrome (FL74), Vero Beach, Florida. The certificated private pilot/owner was seriously injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight that was conducted under the provisions of 14 Code of Federal Regulations (CFR) Part 91.

The pilot was interviewed by telephone, and provided a written statement. The pilot explained that the engine was electronically controlled, and that engine start was "automatic" and the engine would only accelerate from idle once it had "warmed up." Once warm, the pilot would advance the throttle to full operating rpm.

The pilot said that once he advanced the throttle, the engine "reached a satisfactory static rpm of 6,190" prior to takeoff from runway 17. During the initial climb to the south, about 30 seconds after takeoff, the engine rpm decreased to 5,500 and the pilot leveled the glider 170 feet above the ground, at which point the engine stopped producing power.

The pilot entered a left turn to land to the east, and the engine "suddenly regained power." The pilot then turned the glider to return to the airport, and when he leveled the wings, the engine again stopped producing power. Lacking the altitude to return to the airport, the pilot chose a road for a forced landing. The landing area was blocked with cars and power poles, so he landed the glider "hard" in the grass adjacent to the roadway to avoid the obstacles.

The pilot held a Federal Aviation Administration (FAA) private pilot certificate with a rating for airplane single engine land and glider aero-tow. He reported 2,800 total hours of flight experience, 1,000 hours of which were in gliders, and 36 hours of which were in the accident aircraft make and model. His most recent FAA third class medical certificate was issued in January 2007.

According to FAA records, the powered glider was manufactured in 2003 from a kit. The pilot/owner reported that its most recent annual inspection was completed December 2007, at 76 aircraft hours. The glider had accrued about 110 total aircraft hours at the time of the accident.

At 1453, the weather reported at Vero Beach Municipal Airport (VRB), located 6 miles south of the accident site, included visibility 10 miles, few clouds at 5,500 feet, a broken ceiling at 7,000 feet, and winds from 090 degrees at 7 knots. The temperature was 28 degrees Celsius, and the dew point was 22 degrees Celsius. The calculated density altitude was 1,973 feet.

An FAA inspector examined the glider at the accident site and all major components were accounted for. The cockpit canopy was shattered, and pieces were scattered forward of the fuselage. The cockpit, fuselage, and wings appeared largely intact. The empennage was fractured aft of the cabin, but the tailboom and tail control surfaces appeared otherwise intact.

Control continuity was established from the cockpit area to the flight control surfaces. The retractable engine pylon was still deployed and locked in the up position. The engine and propeller appeared intact. The on-scene examination revealed no pre-impact mechanical anomalies.

Reexamination of the glider by the FAA inspector revealed that with electrical power applied, the fuel boost pump did not pump fuel from the pump outlet port.