ERA19LA065 · Czech Sport Aircraft AS Piper Sport

While on an extended base leg of the airport traffic pattern, the pilot reduced engine power and turned on the electrical auxiliary fuel pump; the engine then lost all power. He attempted to restart the engine but was unsuccessful. The pilot executed a forced landing to a field. During landing, the airplane struck a fence and utility pole and sustained substantial damage to both wings.

On-site examination of the airplane revealed that fuel was present in both fuel tanks after the accident. Postaccident examination of the airframe and test runs of the engine did not reveal any preimpact electrical or mechanical anomalies that would have precluded normal operation. During multiple engine test runs, the electric auxiliary fuel pump was cycled several times and operated normally.

A review of the recorded data captured by an engine monitor revealed that, during the accident flight, the oil temperature, cylinder head temperature, and exhaust gas temperature were all within the operating limits specified by the manufacturer. The fuel pressure and fuel flow values during cruise were within the normal range. When the engine lost power, the data showed a temporary decrease in fuel pressure below the minimum pressure specified by the engine manufacturer and subsequent decrease in the fuel flow to 0 gallons per hour. After impact, the fuel pressure returned to the normal range.

Because the engine operated satisfactorily after the accident both with and without the electric auxiliary fuel pump activated, it is unlikely that the engine lost power due to a fuel pump failure. During the accident flight, the recorded values for fuel flow were not abnormally high or erratic, and the cylinder head temperatures were below the maximum limit, so it was unlikely that air or vaporized fuel passed through the fuel flow sensor. An obstruction in the fuel system upstream of the fuel pressure sensor (or exhaustion of the fuel supply) could have resulted in a loss of fuel pressure. However, an obstruction was unlikely because there were no indications of an obstruction during the postaccident engine examination, and fuel was present in the fuel tanks during and after the accident flight, and therefore the engine should not have lost power due to fuel exhaustion. Given this information, it is likely that the loss of engine power was due to an interruption of fuel flow to the engine, though the reason for the interruption cold not be determined based on available information.

Verbatim NTSB analysis and probable cause from the NTSB dataset