Pump-Fuel Paranoid

It’s really a non-argument. The Rotax engine on our Van’s RV-12 happily runs on high-octane, 10% ethanol unleaded. Pump fuel. And aside from the relative cost savings of buying pump fuel, the engine was really designed to run on mogas and you’ll pay a price in parts and labor if you primarily use 100LL avgas. Oil change and tank cleaning intervals are stretched to 100 hours compared to 50 hours when running the engine on 100LL. If leaded fuel is used more than 30% of the time, you’re changing spark plugs every 200 hours compared to 400 hours with mogas. And that gearbox overload clutch? Inspect it only at 1,000 hours compared to 600 hours when using 100LL.

With home base 100LL priced damned near $8.50 per gallon, we gladly bring our own $5.25 per-gallon 93 from the Citgo around the corner from the airfield. But this BYOF practice is far from foolproof for our shared ownership arrangement. I’ve been paranoid about it from the beginning and turns out there’s good reason.

A recent preflight caught sizable amounts of water in the sample. In fact, it seems the entire sampling was water and it was a learning moment for what water/ethanol absorption looks like. Aside from the annoyance of blowing a planned trip, the fix was an unplanned uncowling of the engine and flushing fuel through the gascolator until it finally came out clean. I admit to some tension on the first takeoff run once it was back together and ground-ran.

But before all that was a tail-chase trying to figure out who fueled the airplane last (every pilot in our group puts it away with a full tank) and where the hell the watery gas came from. I like sourcing from the local Citgo because it’s a busy station that pumps a lot of fuel, but that doesn’t mean there isn’t risk of getting watery fuel. But the real challenge is maintaining control of multiple gas cans and because some in our group fly less frequently, that means the ethanol-mixed gas can go stale unless you properly treat it. And even that might not always work.

Additionally, it’s our responsibility to keep the fire marshal and the neighbors happy by not storing multiple cans of fuel in the hangar. To me, it’s worth the small effort to drive to the Citgo and fill the cans with fresh gas for top-offs after flying. Common sense here, folks. We’re still figuring out where the water came from but it’s possible that the cans used for filling the tank on the last put-away had potentially faulty seals and were stored outside—yes, really.

Roll Your Own Fuel Farm

And so it was timely that I came across the smart-looking little fuel farm in the lead photo. Turns out its builder, Scott McElroy, has a background in risk management and is careful as everyone should be about storing fuel for use in his own Van’s RV. My kind of guy. McElroy’s smart setup was quite affordable and relatively simple to construct and even simpler to use and maintain.

The trailer, a small Harbor Freight folding model, can be sized to the fuel storage cell and his is roughly 3 by 5 feet. The rectangular steel fuel tank is a pretty standard 100-gallon design with a filler cap and a threaded female fitting for the pump. McElroy sourced his on Facebook marketplace for around $400. The pump (with a pickup tube) is a 110-volt Fill Rite that flows 15 gallons per minute. He installed a water/ fuel separator in line after the pump, and then a JDM Speed fuel filter.

Safe storage, effective filtration, convenient pumping.

McElroy marks the filter each time he fills the tank, and replaces it after eight fills—or 800 gallons. Like us, he sources ethanol-mixed pump fuel and eventually the stuff gums up filters. If you have filters in the aircraft, they’ll eventually gum up and McElroy notices the one in his RV-12 is ready for replacement at around 150-hour intervals.

This setup sure beats lifting a heavy gas can to fill the aircraft’s single fuel tank, with a filler neck located up high on the fuselage. The hose is a standard Fill-Rite pump hose and gas nozzle. You can use a wooden dowel with 10-gallon markings for measuring the fuel quantity, but a simple float fuel cap could also be used.

For shared arrangements where you might want to record fuel use and charge individual members for the fuel they pump, you could also install a Fill-Rite fuel meter inline. The company makes a nice variety of digital and mechanical fuel flow displays to choose from.

If you had an airport pickup truck as many do, you could of course skip the trailer and keep a similar setup in the bed. But McElroy doesn’t need one. “I pull my fuel trailer behind my Benz SUV very easily, but any car with a hitch could pull it for fill-up at the local gas station,” he said.

If you have a fuel storage setup that works for you, let’s hear about it.

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