Amateur-built STEVE RV 4 N83SB accident near Montrose, Colorado

Probable cause

The total loss of engine power for reasons that could not be determined because a postaccident examination of the engine did not reveal any mechanical malfunctions or failures that would have precluded normal operation.

NTSB analysis

The commercial pilot departed on a local flight and began a 120-mph cruise climb. After the airplane cleared some high terrain, the pilot leaned the engine fuel-air mixture, but the engine began to operate roughly. The pilot enriched the mixture, and the engine began to operate smoothly but then lost total power. The pilot performed emergency procedures, which included an attempted engine restart. The pilot stated that he pumped the throttle twice and that the engine responded with "2 small bursts of 500-600 rpms," but then there was no additional engine power. The pilot executed a forced landing to a nearby private airfield but was unable to reach the runway, and the airplane impacted terrain and farm equipment.

A postaccident examination of the airplane fuel system revealed no anomalies. The carburetor could not be tested because it was destroyed during the accident sequence. A postaccident engine examination showed no evidence of preimpact mechanical malfunctions or abnormalities. Thus, the reason(s) for the total loss of engine power could not be determined.

Text from the NTSB. Open the NTSB docket for CEN18LA068 for the full record.