Primary finding
Probable cause
A loss of engine power due to fuel exhaustion because of a leaking fuel drain valve.
Investigator assessment
Analysis narrative
The pilot was flying his experimental airplane from Florida to Alabama. The airplane was equipped with a 15-gallon fuel tank and the engine consumed about 4.5 gallons of fuel per hour. The pilot said he departed with full fuel and then made 4 fuel stops along the route, stopping about every 70 to 90 minutes. At each stop he filled the fuel tank. On his last fuel stop, after he filled the fuel tank, he took a sample of fuel from the tank’s fuel drain valve to check for water and noticed a few drips of fuel coming from the valve, but no major leaks. The pilot then departed on his final leg of the trip. About 90 minutes into the flight, the engine stopped producing power, and the pilot noted that the fuel sight tube was completely empty. The pilot made a forced landing, resulting in substantial damage to the airframe. A postaccident examination of the airplane revealed the fuel tank was intact and empty. No other breaches in the fuel system were observed; however, blue staining was noted around the fuel sump-valve consistent with it having been leaking. Fuel staining was also observed on the right flaperon. The pilot said the fuel valve was leaking a few months before the accident, but he fixed it and had not had another problem with the drain valve until the accident flight. Based on this information, it is likely that fuel leaking from the drain valve decreased the amount of fuel available over the duration of the accident flight, ultimately resulting in fuel exhaustion and a subsequent total loss of engine power.
Source record
Factual narrative
On August 3, 2023, at 1326 central daylight time, N3HH, an experimental amateur-built Long Charles Jackson Avid Flyer airplane, sustained substantial damage when it was involved in an accident near Wetumpka, Alabama. The pilot was not injured. The airplane was operated as a 14 Code of Federal Regulations Part 91 personal flight. The pilot was flying the airplane from Wimauma, Florida, to Wetumpka Airport (08A), Wetumpka, Alabama. The airplane was equipped with a 15-gallon fuel tank located in the wing and the engine consumed about 4.5 gallons of fuel per hour. The pilot said he departed with full fuel and made 4 fuel stops along the route, stopping about every 70-90 minutes. At each stop he filled the fuel tank. On his third fuel stop, he noted that it took 10 gallons to fill the tank when it should have only taken about 7 gallons. He justified the discrepancy by thinking that he had filled the tanks too quickly on the previous stops, causing the fuel to overflow the cap before it had a chance to settle into the other chambers of the tank. The pilot then flew to Dawson, Georgia, which was his last fuel stop before landing at 08A. In Dawson, he purchased 6 gallons of fuel. He looked at the airplane’s fuel sight-gauge and it was “full.” Before departure, the pilot took a sample of fuel via the fuel drain valve located under the right wing and it was absent of water. When he took the sample, he observed a few drops of fuel drip from the valve, but no noticeable leaks. The pilot then departed for 08A. The pilot said that when he was about 6 miles from the airport, about 90 minutes into the flight, the engine began to misfire. The fuel sight tube was completely empty and the clear fuel filter located under the panel was “intermittently gushing fuel.” Seconds later, the engine stopped producing power. The pilot attempted to make a forced landing to a rural gravel road but landed to the right of it and flipped over into a ditch, resulting in substantial damage to the fuselage. A postaccident examination of the airplane revealed the fuel tank was intact and empty of fuel. No other breaches in the fuel system were observed; however, the fuel drain valve did exhibit blue staining consistent with a leak. Fuel staining was also observed on the right flaperon. The pilot said that the fuel drain valve had been leaking a few months before the accident. He fixed it by removing the valve and cleaning the O-ring seal, which had a small piece of debris stuck in it from inside the fuel tank. He also flushed the tank with fuel to be sure there was no debris in it. The pilot said that he had not had another problem with the drain valve until the accident flight.