On October 31, 1998, an Ercoupe (eng & Research Corp.) 415-C (registration N99924) was involved in an aviation accident near Hartselle, AL. Investigators recorded the probable cause as: The carburetor float was found stuck in the full needle valve open position due to excessive solder on the float fulcrum contacting the bowl wall, resulting in an excessively rich fuel mixture and engine power loss. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An aircraft experienced engine power loss while turning onto the downwind leg for landing. The pilot attempted a field landing but collided with a power line and then the ground. Postcrash examination revealed an excessively rich fuel mixture due to a stuck carburetor float.
Engine Power Loss and Collision
During the approach to landing, as the pilot turned onto the downwind leg, the engine lost power. The pilot maneuvered the aircraft toward a field for an emergency landing. During the descent, the aircraft struck a power line and subsequently impacted the ground.
Postcrash Examination
After the accident, the engine was examined. The examination showed that the engine had been operating with an excessively rich fuel mixture. The cause was traced to the carburetor: the float was stuck in the full needle valve open position. This condition resulted from excessive solder on the float fulcrum, which contacted the bowl wall and prevented proper movement.
Recent Modification
The carburetor had recently undergone a modification. A new style needle valve had been installed, which required the addition of weight to the float fulcrum using solder. The excess solder on the fulcrum interfered with the float's freedom of movement, leading to the stuck valve and the rich mixture that caused the power loss.
Probable cause
The carburetor float was found stuck in the full needle valve open position due to excessive solder on the float fulcrum contacting the bowl wall, resulting in an excessively rich fuel mixture and engine power loss.