Pilot Debrief

AERONCA 7AC near Melrose, TN — 2022-05-29

Final reportERA22LA249
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Date
2022-05-29
Location
Melrose, TN, USA
Aircraft
AERONCA 7AC
Registration
N1294E
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Cruise

Probable cause

A total loss of engine power due to carburetor icing.

NTSB narrative

The pilot reported that he departed from the private grass airstrip on his farm and had been flying for about 25 minutes. He climbed to 2,500 ft mean sea level (msl) before descending to 1,500 ft msl and turning to the northeast. The airplane’s engine then lost all power and the pilot turned northwest toward “river bottoms” that were about 1 mile away to attempt a forced landing. When it was obvious that the airplane could not reach the river bottoms, he maneuvered to an area that did not have any large trees. During the forced landing, the airplane’s right wing struck a tree and the airplane then spun 180° before coming to rest, which resulted in substantial damage to the right wing and rudder. In his written statement, the pilot did not indicate whether he had attempted to restart the engine or had applied carburetor heat after the engine lost all power. The on-site examination of the airplane found the carburetor heat in the OFF position. The pilot reported that he had departed with about 12 gallons of fuel on board. Although only about an inch of fuel was found remaining in the 13-gallon fuel tank the day after the accident, the examination revealed that the gascolator bowl was missing/broken, which likely would have allowed any remaining fuel to drain out. A fuel selector valve had been installed behind the firewall between the fuel tank and the fuel line that led to the gascolator. The installed fuel selector valve was not labeled with ON and OFF locations and the valve was able to be turned 360° with ease, with no apparent detents. The airframe examination also revealed that the original fuel shutoff valve handle located on the engine control panel had been disconnected. A postaccident examination of the engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. It is possible that during the flight the modified fuel selector valve vibrated, or was inadvertently moved by the pilot, to a position that stopped or reduced the fuel flow to the gascolator. However, a weather reporting station located about 8 miles from the accident site indicated that the temperature was 84° F, and the dew point was 61°F. Federal Aviation Administration (FAA) Special Airworthiness Information Bulletin CE-09-35, Carburetor Icing Prevention, indicated that the weather conditions at the time were conducive to serious icing at glide power. Based on the reported conditions and accident scenario, the airplane likely encountered serious carburetor icing conditions during the 1,000 ft descent, which resulted in a total loss of engine power.

Analysis

Primary failure mode
Fuel management
First missed decision gate
Pilot could have checked fuel levels before departure to ensure adequate fuel.

NTSB coding

Evidence available

  • Photos
  • 6 docket documents
View NTSB final reportView NTSB docket

Docket documents6

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