Aeronca 65CA N31915 accident near Hardwick, Vermont

Probable cause

The improper maintenance of the carburetor, which resulted in a total loss of engine power due to carburetor flooding.

NTSB analysis

The pilot reported that a preflight inspection and engine run-up revealed no anomalies. Shortly after the airplane lifted off the runway, the engine began "misfiring" and then experienced a total loss of power. The pilot maneuvered the airplane straight ahead, and it subsequently impacted a tree, which resulted in substantial damage to the forward fuselage, engine firewall, and left wing. Although the pilot and passenger were both seriously injured during the accident, both of their seat belts remained intact and firmly anchored to their respective seats; the belts' latching mechanisms operated normally.

The engine sustained extensive impact damage, and the crankshaft could not be rotated by hand during postaccident examination. Several of the spark plugs were loose and could be removed by hand; it could not be determined whether the spark plugs had been improperly installed during the airplane's most recent inspection or sometime thereafter. In addition, the spark plugs exhibited black sooty deposits, which is indicative of the engine operating with an excessively rich fuel/air mixture. Examination of the carburetor revealed that the float needle would not seat properly and that the float level specified by the manufacturer could not be maintained; these conditions would be expected to result in an excessively rich fuel/air mixture at high engine power settings. Therefore, based on the evidence, it is likely that the engine was operating with an excessively rich fuel/air mixture, which resulted in the carburetor flooding and the subsequent loss of engine power. Although the engine maintenance logbooks documented that an overhauled carburetor had recently been installed on the airplane and that a subsequent test run was successfully performed, they did not document when or by whom the carburetor overhaul was performed.

Text from the NTSB. Open the NTSB docket for ERA13LA397 for the full record.