American Aviation AA-1A N7254L accident near Sparta, Tennessee

Probable cause

A total loss of engine power due to an accumulation of carburetor ice, resulting in an off-airport landing and substantial damage to the airplane.

NTSB analysis

An annual inspection had just been completed on the airplane, and the following day the pilot conducted a test flight directly over the airport. Shortly after takeoff, the pilot climbed to 6,500 ft mean sea level (msl) while conducting rectangular patterns directly over the airport for several minutes and then initiated a descent to 4,500 ft msl. During the descent, without any warning, the airplane sustained a loss of engine power. The pilot was unsuccessful in his attempts to restart the engine, resulting in the need to conduct a forced landing. As he entered the airport traffic pattern, the airplane was too high to land on the runway, so he conducted a side slip to lose altitude, but over-corrected and was too low to reach the desired runway. Unable to glide to the runway, the pilot landed short of the runway on rough, hilly terrain, which resulted in substantial damage to the airframe.

Postaccident examination of the engine, fuel system, and induction system revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. The weather conditions reported at the time of the accident were conducive to serious carburetor icing. Examination revealed that the carburetor heat was not in use when the airplane impacted the ground based on damage signatures to the bottom side of the heat box; the carb heat butterfly valve was in the “cold air” position and could not be activated due to the deformation of the box. The pilot also did not report that he used the carburetor heat. Based on the temperature and dew point at the altitude about where the loss of engine power occurred, the conditions were favorable for serious carburetor icing at the glide power setting and very close to the cruise power setting; therefore, it is likely that carburetor ice accumulated while descending and resulted in a loss of engine power.

Text from the NTSB. Open the NTSB docket for ERA23LA059 for the full record.