Amateur-built IV N9259M accident near North Canaan, Connecticut

Probable cause

The pilot's mismanagement of the airplane's altitude, airspeed, and course during a forced landing following a partial loss of engine power, which resulted in collision with trees and terrain. Contributing was the pilot’s inadvertent omission of stowing the carburetor choke before takeoff and in-flight after experiencing a partial loss of engine power.

NTSB analysis

The pilot reported that shortly after takeoff during climbout, the engine began to sputter. He checked the magnetos, fuel switches, ignition, and fuel pressure. He did not notice any abnormalities; however, full engine power did not return. He subsequently performed a 180° turn back to the runway, but the airplane was too high and fast to land. The airplane overflew the runway toward a wooded area, and as the pilot attempted to increase power, the engine again sputtered. The pilot maintained a safe airspeed and flew into the tops of the trees. The airplane momentarily was suspended in the trees but then fell vertically and impacted muddy and swampy terrain in a nose-low attitude.

Examination of the airplane did not reveal any evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation.

The pilot reported that he utilized full carburetor choke to start the engine and partial carburetor choke to warm-up the engine. He could not recall stowing the lever prior to takeoff (as was required for this type of choke) nor did he recall checking the lever during the troubleshooting in-flight. The pilot reported the partial loss of power would worsen only when he attempted to add full power and that the engine would run normally at idle power.

Weather conditions in the area at the time of the accident flight were conducive to serious carburetor icing at glide power; however, the description of the partial loss of engine power and the phase of flight at which it occurred were not indicative of carburetor icing.

Given the circumstances described by the pilot, it is likely that the carburetor choke remained partially applied during the takeoff and climbout, which flooded the engine at high power settings. Although the spring-loaded choke lever was photographed in the stowed position shortly after the accident, it is possible that the choke switch was moved to that position during the impact sequence or during the pilot’s evacuation after the accident.

The pilot reported that he turned back toward the departure runway while he was troubleshooting the engine issue, but the airplane was too high and fast to land and overflew the runway. Had the pilot managed the altitude, airspeed, and course toward the runway better, the collision with trees likely could have been avoided and a safe landing likely could have been made at the airport.

Text from the NTSB. Open the NTSB docket for ERA22LA016 for the full record.