Paso Robles Municipal Airport
Aircraft Accident/Incident Report

Paso Robles, California 93446
Friday, October 21, 2011 4:15 PDT

The pilot reported that when he was established inbound on the second instrument approach, after missing the first one, the engine began to make a sound similar to fuel starvation. The pilot checked to ensure that the mixture was at full rich and turned on the fuel pump, but there was no change in the sound of the engine. He then switched fuel tanks, but there was still no change, and the airplane was losing altitude. The pilot stated that he had the throttle at full forward but that the engine was not making full power. He subsequently made a forced landing to an open field. During the postaccident examination, downloaded data from the airplane’s multi-function display (MFD) revealed that when he began the missed approach at 04:01:00, the pilot did not return the engine mixture to a full rich condition; the climb back to 6,000 feet was performed at a setting less than full rich. The data indicated that at 04:06:00, the engine was making full power; however, the fuel flow was at a very lean setting. The data further indicated that the cylinder head temperature (CHT) and the Turbine Inlet Temperature (TIT) were elevated. One of these two elevated temperatures likely tripped a red annunciator on the panel, prompting the pilot to go to the full rich condition at 04:06:30. When the pilot was leveling off, the CHTs started a steady drop along with the oil temperature. The TIT immediately dropped to a more normal value when the pilot advanced the mixture to full rich. At 04:09:30, the manifold pressure dropped, which indicated that the pilot closed the throttle. At 04:10:15, the data revealed that the airplane began a relatively normal descent, and that the MAP continued to decrease in steps. About 2 minutes later, or about 1 minute 45 seconds prior to the end of the data, the descent rate increased to about 1,800 feet per minute and remained there until the end of the data. At this time the MAP indicated that the throttle was closed or nearly closed. Data for MAP and TIT are consistent with the engine running with the throttle closed, or nearly closed, throughout the final descent until the data ended at 04:14:06. Accordingly, the MFD data did not reveal any evidence of a powerplant-related failure. Postaccident testing and examination of fuel samples revealed that two out-of-range results were noted, consistent with aged fuel. The postaccident examination also revealed that spark plug coloration was indicative of an even distribution of fuel to each cylinder and that there was no indication during the examination of a clogged fuel nozzle. Additionally, MFD data did not support the presence of a plugged fuel nozzle during the accident flight. Therefore, the investigation could not definitively determine if the condition of the fuel was contributory to the partial loss of power. During the postaccident examination, the engine was run successfully and no mechanical anomalies or failures were noted that would have precluded normal operation; the loss of engine power could not be duplicated.

A loss of engine power while maneuvering for reasons that could not be determined because postaccident examination did not reveal any anomalies that would have precluded normal operation.