CEN19LA060

The pilot was conducting a personal flight; while in cruise flight, the engine experienced a momentary and substantial loss of rpm. The pilot moved the mixture to the full-rich position, turned on the carburetor heat, and switched to the right fuel tank. The engine recovered power, and the pilot left the carburetor heat on for about 3 minutes and then slowly turned it off. About 2 minutes later, the engine lost all power. The pilot activated the starter, but it did not engage. The pilot chose to execute a forced landing on a road, during which the airplane impacted trees, bounced, and then came to rest inverted on a snow-covered embankment. Postaccident examination of the engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. The temperature and dewpoint at the time of the accident were not conducive for the formation of carburetor icing. The airplane had an adequate amount of fuel onboard at the time of the accident. Therefore, the reason for the loss of all engine power could not be determined.

On January 19, 2019, about 1125 central standard time, a Stinson 108-1, N97969, sustained substantial damage when it was involved in an accident on the Menominee Indian Reservation near Keshena, Wisconsin. The private pilot sustained serious injuries and the three passengers sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that the purpose of the personal flight was to travel to Ford Airport (IMT), Iron Mountain, Michigan. The airplane had 26 gallons of fuel onboard prior to departure. While in cruise flight, the engine sustained a momentary and substantial loss of rpm. The pilot reported that cruise power settings was about 2,300 rpm and the rpm needle decreased down to about 1,500 rpm. The pilot applied the mixture to the full rich position, activated the carburetor heat, and switched to the right fuel tank. The engine recovered and the pilot left the carburetor heat on for about three minutes and then slowly turned it off. About two minutes after the carburetor heat was turned off, the engine ceased producing power. The pilot reported the propeller did not windmill after the loss of engine power. The pilot activated the starter and it did not engage. The pilot observed an asphalt road surrounded by trees on both sides where he decided to execute a forced landing. During the landing, the airplane impacted the trees and bounced on the road, coming to rest upside down on a snow-covered embankment. The occupants were able to egress without further incident. The airplane sustained substantial damage to the fuselage, both wings, and the empennage. A postaccident examination of the engine by the Federal Aviation Administration (FAA) found no preimpact mechanical malfunctions or failures that would have precluded normal operation. The temperature and dewpoint at the time of the accident were not conducive for the formation of carburetor icing per the carburetor icing probability graph from the FAA Special Airworthiness Information Bulletin CE-09-35 Carburetor Icing Prevention. Although requested, the pilot did not submit the National Transportation Safety Board Pilot/Operator Aircraft Accident/Incident Report Form 6120.1.