CEN18LA156 · Laminar Lancair 360

The airline transport pilot was conducting a personal flight with a pilot-rated passenger in an experimental, amateur-built airplane. The pilot reported that, during flight at 10,000 ft, the airplane experienced moderate to severe turbulence for a few seconds. Shortly after, the engine stopped producing power without warning. The pilot immediately attempted to restart the engine to no avail. He flew at best glide speed toward the nearest airport, located about 12 nautical miles away, but landed short of the runway in a pasture, during which the airplane encountered sagebrush, which caused the landing gear to collapse as the airplane bounced and skidded to a stop; the fuselage sustained substantial damage.

The examination of the airplane at the accident site revealed that the emergency fuel shutoff valve, which was located on the right side of the center console under the instrument panel, was about 1/4 of the way between the on (horizontal) position and the off (vertical) position. The valve could not be seen by the pilot. Further, the pilot-rated passenger stated that he could not see the emergency fuel shutoff valve. He was not sure if his knee hit the valve handle and shut off the fuel flow from the header fuel tank to the engine during the turbulence event. The onboard flight and engine monitoring system indicated that the airplane was about 10,000 ft mean sea level when it experienced about a 2g vertical acceleration. The engine data indicated a rapid decrease of fuel flow after the 2g acceleration with a coinciding decrease in exhaust gas temperatures and fuel pressure.

About 30 gallons of fuel was drained from the airplane before it was transported to the recovery facility. An engine examination and test run were conducted, and the engine performed satisfactorily. A second test was conducted to determine the effectiveness of the emergency fuel shut off valve and where it needed to be positioned before it cut off all fuel to the engine. There was no indication of a power loss until the valve handle was in the full vertical position, which then caused the engine to stop within about 10 seconds.

The pilot-rated passenger reported that he had recently purchased the airplane and that he and the pilot were flying the airplane to his home base. He stated that although he and the pilot were experienced pilots, neither had any flight time in the airplane except for the orientation flight that the pilot had received.

Given the engine data, it is likely that the pilot-rated passenger's knee inadvertently hit the emergency fuel shutoff valve during the turbulence event and caused it to shut off the fuel flow from the header tank to the engine. Further, had the pilot been familiar with the airplane, he would have known where the fuel selector valve was, regardless of whether it was easy to see, and would have checked it when the engine lost power as a memory item check in the emergency procedures.

Verbatim NTSB analysis and probable cause from the NTSB dataset