Narrative:

I was flying my experimental aircraft, in clear VFR WX on a test flight in the local area. I departed mathis field (san angelo's airport) and left the airport area to the west. After doing some maneuvering west of the airport area, I headed east, crossing over the far south end of the city, about 10 mi north of the airport. I was climbing from an altitude of 2700 ft while I was maneuvering west of the airport to 5500 ft while heading east. As I was crossing the south end of san angelo, I started to lose engine RPM and altitude. I continued to fly straight and level (east) while I surmised the situation. My fuel pressure gauge indicated that I was losing fuel pressure and was now down to 0.5 psi which would only maintain about 3000 engine RPM. I was in a slow controled descent with this partial power, and at an altitude of around 2400 ft (about 600 ft AGL) then I initiated a 180 degree turn back to the west and away from the city. During this time I was trying to increase fuel pressure by turning on my auxiliary fuel pump and switching tanks. My fuel pressure increased as I switched from my main tank to the wing tank and I was able to increase engine RPM to full (6500 RPM) and start climbing again. I flew on to ducote field, an uncontrolled private air park some 10 mi west of mathis field, and landed immediately. A piece of silicone sealant was stuck in the selector valve inlet from the main tank causing the fuel flow problem. This was easily removed and I returned to mathis field and my hangar without incident. I am submitting this report to document my descent and turn over the south suburbs of san angelo.

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Original NASA ASRS Text

Title: ENG PROBLEM CAUSED TEST ACFT TO LOSE ALT. LOW FLT OVER POPULATED AREA.

Narrative: I WAS FLYING MY EXPERIMENTAL ACFT, IN CLR VFR WX ON A TEST FLT IN THE LCL AREA. I DEPARTED MATHIS FIELD (SAN ANGELO'S ARPT) AND LEFT THE ARPT AREA TO THE W. AFTER DOING SOME MANEUVERING W OF THE ARPT AREA, I HEADED E, XING OVER THE FAR S END OF THE CITY, ABOUT 10 MI N OF THE ARPT. I WAS CLBING FROM AN ALT OF 2700 FT WHILE I WAS MANEUVERING W OF THE ARPT TO 5500 FT WHILE HDG E. AS I WAS XING THE S END OF SAN ANGELO, I STARTED TO LOSE ENG RPM AND ALT. I CONTINUED TO FLY STRAIGHT AND LEVEL (E) WHILE I SURMISED THE SITUATION. MY FUEL PRESSURE GAUGE INDICATED THAT I WAS LOSING FUEL PRESSURE AND WAS NOW DOWN TO 0.5 PSI WHICH WOULD ONLY MAINTAIN ABOUT 3000 ENG RPM. I WAS IN A SLOW CTLED DSCNT WITH THIS PARTIAL PWR, AND AT AN ALT OF AROUND 2400 FT (ABOUT 600 FT AGL) THEN I INITIATED A 180 DEG TURN BACK TO THE W AND AWAY FROM THE CITY. DURING THIS TIME I WAS TRYING TO INCREASE FUEL PRESSURE BY TURNING ON MY AUX FUEL PUMP AND SWITCHING TANKS. MY FUEL PRESSURE INCREASED AS I SWITCHED FROM MY MAIN TANK TO THE WING TANK AND I WAS ABLE TO INCREASE ENG RPM TO FULL (6500 RPM) AND START CLBING AGAIN. I FLEW ON TO DUCOTE FIELD, AN UNCTLED PRIVATE AIR PARK SOME 10 MI W OF MATHIS FIELD, AND LANDED IMMEDIATELY. A PIECE OF SILICONE SEALANT WAS STUCK IN THE SELECTOR VALVE INLET FROM THE MAIN TANK CAUSING THE FUEL FLOW PROBLEM. THIS WAS EASILY REMOVED AND I RETURNED TO MATHIS FIELD AND MY HANGAR WITHOUT INCIDENT. I AM SUBMITTING THIS RPT TO DOCUMENT MY DSCNT AND TURN OVER THE S SUBURBS OF SAN ANGELO.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.