Primary finding
Probable cause
The partial loss of engine power for undetermined reasons.
Investigator assessment
Analysis narrative
The pilot was conducting a personal flight. During the flight, he monitored the carburetor temperature gauge and used full, partial, and no carburetor heat settings as appropriate. While landing at his private, high-elevation airport, he initially had partial carburetor heat selected but then turned it off as he typically did to preclude ingestion of unfiltered air into the engine while landing on a dirt runway. During the approach, the airplane drifted left of the runway, so the pilot decided to go around. He advanced the engine power slightly, but the engine did not respond. He then advanced the engine power to full, but the engine still did not respond. The pilot then conducted a steep right turn and applied right rudder to land the airplane on the runway and avoid trees. He was not certain if the airplane stalled, but the right wingtip contacted the ground, and the airplane "pancaked" on the runway. The airplane sustained substantial damage to the fuselage and both wings. After the accident, the pilot stated that he did not “adequately” clear the carburetor during the approach and that it was possible the carburetor had "iced up" during the descent. However, the temperature and dew point at the time of the accident put the airplane outside of conditions conducive for icing; therefore, it is unlikely that carburetor accumulated icing. Thus, the reason for the loss of engine power could not be determined based on the available evidence.
Source record
Factual narrative
On December 23, 2018, about 1510 mountain standard time, a Cessna 182G, N3120S, sustained substantial damage when it was involved in an accident near Norwood, Colorado. The private pilot sustained no injury. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported he was flying his airplane south of Telluride, Colorado, over the San Juan mountain range which is in the San Juan National Forest. He said that the weather conditions at the time were clear visibility, cold temperatures, no visible moisture, and a few scattered clouds. While in a descent profile, he observed "backlit ice crystals" for a short period and noted no airframe icing. During the flight, he utilized full, partial, and no carburetor heat settings while monitoring the carburetor temperature gauge. He stated that the carburetor temperature gauge indicated normal range during operations with partial and full carburetor heat. The pilot decided to perform a straight in approach to his private airport, landing to the northeast. He initially had partial carburetor heat selected but turned the carburetor heat off as he typically did to preclude the ingestion of unfiltered air into his engine while landing on a dirt runway. During the approach the airplane drifted to the west so the pilot elected to go around. He advanced the engine power slightly but the engine did not respond. He then advanced the engine power to full with no response from the engine. The pilot then performed a steep right turn and applied right rudder to put the airplane down on the dry dirt runway and avoid trees. He was not certain if the airplane stalled, but the right-wing tip contacted the ground and the airplane "pancaked" on the runway which resulted in damage to the nose landing gear, the propeller, and wrinkles in the skins of both wings. Various propeller impact marks were made to the dirt prior to the final resting spot of the airplane on the runway. The pilot shut down the engine and egressed without further incident. The airplane sustained substantial damage to the fuselage and both wings. The pilot reported that he did not clear the carburetor "adequately" during his straight in approach. He said it was possible that the carburetor had "iced up." Per the carburetor icing probability graph from the Federal Aviation Administration Special Airworthiness Information Bulletin CE-09-35 Carburetor Icing Prevention, the weather conditions at the time of the accident would have put the flight just outside of conditions conducive for icing at glide and cruise power settings.