NTSB Factual Report

On January 4, 2018, about 1600 mountain standard time, a Barnes RV-4 airplane, N83SB, lost engine power and executed a forced landing near Montrose, Colorado. The commercial rated pilot was not injured, and the airplane sustained substantial damage. The airplane was registered to and operated by a private individual under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Day visual meteorological conditions prevailed at the time of the accident, and a flight plan was not filed. The local flight departed the Clifford Field Airport (1CO4), Olathe, Colorado, about 1555.

According to the pilot, he departed 1CO4 and began a 120-mph cruise climb. After clearing some high terrain, the pilot leaned the engine mixture and the engine began to operate rough, so he began to enrich the mixture. Subsequently, the engine began to operate smoothly, and then lost total power. The pilot performed his emergency procedures which included an attempted engine restart. The pilot pumped the throttle twice, the engine responded with "2 small bursts of 500-600 rpms", and then no additional engine power. The pilot executed a forced landing to a nearby private airfield; however, was unable to make the runway, and the airplane impacted terrain and farm equipment.

Examination of the airplane by a Federal Aviation Administration inspector and the pilot revealed the fuel system and fuel lines were clear of contaminants and no issues were noted. The engine carburetor was destroyed during the accident sequence. No mechanical anomalies were noted with the airframe or engine.

NTSB 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.