Cessna 172I N46028 accident near Los Angeles, California

Probable cause

A partial loss of engine power due to carburetor ice accumulation.

NTSB analysis

According to the pilot, the purpose of the flight was to conduct a sunrise flight for his passenger. He reported that it was the airplane’s first flight of the morning and after a thorough preflight inspection, engine runup, and departure, he climbed the airplane to about 1,400 above ground level (agl) and completed the level-off checklist. Moments later, the engine began to lose power, and he turned on the carburetor heat and continued the climb. He made a right turn back toward the airport but realized that the airplane’s altitude was insufficient to make it to the runway, and he performed a forced landing to the nearest open area. During the landing roll, the airplane nosed over and came to rest inverted, resulting in substantial damage.

A witness, who was a Federal Aviation Administration (FAA) inspector, observed the accident airplane take off on the accident flight. He stated that the engine was running rough, but it was not emitting smoke or vapor.

Examination of the airframe and engine revealed no evidence of preimpact malfunctions or anomalies. Residual fuel was found in fuel lines and fuel components in the airframe and engine, and there was evidence of fuel spillage at the accident site.

Review of weather information indicated that the conditions at the departure airport were conducive to the development of serious carburetor icing at glide power settings. Based on the lack of mechanical anomalies found during postaccident examination, carburetor ice likely developed while the airplane was operating on the ground at reduced power settings before takeoff, which resulted in the engine roughness during takeoff observed by the witness and the subsequent partial loss of engine power.

Text from the NTSB. Open the NTSB docket for WPR25LA037 for the full record.