Ryan L17 N5042K accident near Livingston, Illinois

Probable cause

A total loss of engine power due to fuel injection system contamination from an unknown source.

NTSB analysis

The pilot receiving instruction reported that the purpose of the instructional flight was to practice various flight maneuvers, which were successfully performed. About halfway back to the departure airport, the pilot noticed the engine was “running rough.” The pilot proceeded to lean the airplane’s fuel mixture to correct the problem and noticed that the fuel flow gauge was “pegged.” The pilot continued to lean the mixture and adjusted the throttle, but no response was received from his inputs. The airplane began to lose altitude, and the pilot receiving instruction performed a forced landing to a flat muddy field. During the landing rollout, the nosewheel turned left in the mud, the airplane spun around, both wings and the propeller impacted the ground, and the airplane came to rest upright. The airplane sustained substantial damage to both wings.

The flight instructor, who was also a mechanic, reported that, when the engine was running roughly, he tried to lean the mixture with no response. The flight instructor also reported that the fuel flow gauge needle had advanced into the manifold pressure side of the gauge and that the throttle had no response. The flight instructor assumed that the fuel control unit had a mechanical issue.

Postaccident examination of the airplane found no anomalies that would have precluded normal operation. Testing of the fuel injection system found internal damage to the fuel control valve. The internal damage was likely consistent with fuel injection system contamination.

In addition, the interior of the fuel pump had a dark deposit that was firmly adhered to the surface and could not be removed. When viewed under magnification, the deposit was found to be consistent with corrosion of the surface material. Thus, corrosion was likely present in the contamination.

The engine manufacturer’s guidance stated that fuel injection system contamination may lead to “component damage, erratic engine operation, loss of power, or engine shutdown.” Although the source of the contamination could not be determined based on the available evidence, the contamination likely caused the fuel control system to fail, which led to the total loss of engine power during the accident flight.

Text from the NTSB. Open the NTSB docket for CEN22LA128 for the full record.