Frugal Flyer: Free engine overhaul

Saving by buying mogas equal the cost of an overhaul

April 1, 2010

A Watching a fellow pilot heft several five-gallon cans of auto fuel onto the wing of his experimental airplane and pour the contents into the fuel tanks, I couldn’t resist the urge to tease him about being such a cheapskate.

After all, this was a Russian-made aerobat that cost more than $150,000. Wasn’t he willing to part with an extra 15 bucks or so for real avgas?

“That would be convenient,” he admitted. “But this fuel comes with a free engine overhaul.”

My puzzled look encouraged him to elaborate. Premium mogas cost about a dollar a gallon less than avgas at the time. The Russian engine consumed about 15 gallons an hour, so after 1,000 hours of flying, the owner expected to save about $15,000, which happened to be the exact price of an overhaul on the 360-horsepower Vedenyev M-14P that powered his airplane. It was pretty compelling logic, made even more so by the fact that the same engines run just fine on lower-grade fuels in their motherland, and other aircraft with identical engines had reached TBO and beyond on mogas here.

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The problems with mogas additives such as ethanol are significant and well documented. But having watched the Russian aerobat fly year after year with no engine troubles, I envied the savings that mogas provided. Now, the light sport aircraft category, with its Rotax engines, are giving auto gas new life at some U.S. airports—and LSA could encourage the spread of premium unleaded fuel at airports around the country.

Rotax engines are designed to fly on mogas, and it works better in them than 100LL. Pilots who put avgas in their Rotax engines must operate them at higher, less-economical power settings—to avoid lead fouling—and change the oil four times as often (at 25-hour intervals instead of 100).

Fewer than 150 of the 5,000 general aviation airports in the United States sell mogas on their ramps, so pilots flying aircraft with Rotax engines must buy avgas that’s both more expensive at the pump and more costly in terms of ongoing maintenance. I got to experience that situation firsthand recently on a trip from Frederick, Maryland, to Sebring, Florida (750 nm), and back in AOPA’s 2010 “Fun to Fly” Remos GX sweepstakes airplane. Checking for airports along our route that sold mogas, it quickly became apparent there were none.

But when we arrived at Sebring, I caught a glimpse of a self-service fuel pump that Rotax owners—along with those who own experimental aircraft and FAA-certified airplanes with auto-fuel STCs—are sure to love. It offered Jet-A, 100LL, and premium unleaded fuel (without ethanol). The price for mogas, about $3.50 a gallon, was about 70 cents a gallon more than local gas stations—but a full dollar a gallon less than avgas.

After 2,000 hours (the Rotax TBO) of saving $1 a gallon at a fuel burn of about five gph, the LSA owner nets $10,000 in reduced fuel expenses. If the fuel pump is on the field, the hassle of carting gas cans around in the trunk is eliminated.

Gail Moser, vice president of marketing at QT Technologies in Dallas, the company that built the self-service fuel facility at Sebring, said the cost to airports for adding mogas is tiny. “Each of our self-service fuel terminals can handle up to four different kinds of fuel. Adding mogas is not a significant added cost.”

Fewer than 20 of more than 1,000 airports that have purchased self-service fuel stations from QT Technologies have elected to sell mogas. But with the growing popularity of LSAs with Rotax engines, that could change.

E-mail the author at [email protected].

Dave Hirschman

Dave Hirschman | AOPA Pilot Editor at Large, AOPA

AOPA Pilot Editor at Large Dave Hirschman joined AOPA in 2008. He has an airline transport pilot certificate and instrument and multiengine flight instructor certificates. Dave flies vintage, historical, and Experimental airplanes and specializes in tailwheel and aerobatic instruction.