Leaking Fuel Line

Once I started the engine and made it to the runup area, the Dynon D-180 registered about 10 gallons in the selected right tank (I have a Lycoming O-235-L2C engine installed and typically I burn about 5-6 gallons an hour). I thought it was peculiar, but I attributed the loss of five gallons to starting, taxi and runup. I took off and headed the 30 miles to my practice area.

Editorial Staff

Thursday, September 15, 2016 at 12:00 AM ET

Verified

The Kodiak 100 is a versatile turboprop for a number of special applications. Courtesy Daher

Key Takeaways:

A pilot experienced rapid and unexplained fuel loss during a test flight, initially attributing decreasing fuel gauge readings to minor issues before realizing the severity of the problem.
The cause was a hidden leak in a braided stainless steel fuel line under the engine cowl, where the inner rubber line had perforated, spraying fuel directly onto the exhaust stack.
The incident created a significant fire hazard and served as a humbling lesson on critical component failures and the importance of promptly declaring emergencies despite fear of embarrassment.

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I was about halfway through my phase one flight-test program for the Zenith Zodiac 601XL experimental I built. The plane carries 30 gallons of fuel in two 15-gallon wing-mounted tanks. With the dihedral in the wings and the tanks half-full, I can see fuel at the outboard corner of the tank when looking through the filler neck. I clearly remember noting half-full tanks during my preflight inspection, which was confirmed once I turned on the avionics, which reports in tenths of a gallon.