Plane & Pilot
Tuesday, August 9, 2011

Save On Avgas


American avgas is becoming almost as expensive as European petrol. Here’s how to use less of it.


2 Fly Cleaner
If you're like me (and I know I am), you'll forget to use a climb checklist and may leave takeoff flaps down and cowl flaps extended during some portion of the climb. Takeoff flaps obviously need to be retracted as soon as practical. Most airplanes aren't as efficient in climb with flaps extended.

Under some conditions, you'll need full cowl flaps during the climb. Unless it's a really hot day, however, the majority of airplanes can cool the engine sufficiently with cowl flaps in trail. Very hot days may even demand some cowl flaps at cruise, but if you just happen to forget them, fully open cowl flaps can cost you up to three knots on a Skylane. Ask me how I know.

Similarly, make certain you coordinate rudder position for climb and cruise. If you have rudder trim, you can trim the vertical fin for dead center. If you don't, simply releasing the right pedal should allow a properly rigged airplane to fly straight. Flying with the ball half out of center can cost you at least one knot, two on some airplanes. Again, I've learned from experience.

Finally, it can't hurt to keep the airplane clean and well waxed. Cleanliness is next to godliness. You're guaranteed to at least THINK it's faster, even if it isn't. Don't believe everything you read on the bottom of aircraft-wax cans, but it's only logical that a slicker airplane with some of the rough edges smoothed out will be faster than a dirty machine. You might not be able to measure the difference, but aviation is a game of inches.

3 Consider Operating Lean Of Peak
I know, I know, not everyone agrees with running an engine lean of peak (LOP). There are, nevertheless, some astute engineers who endorse the philosophy of George Braly and Tim Roehl of GAMIJectors in Ada, Okla., that running the engine's exhaust gas temperature (EGT) 50-100 degrees on the lean side of peak can save you another 15%-20% in fuel cost, with no ill effects on the engine. I was once a naysayer on LOP operation, but I've gradually been dragged, kicking and screaming, to the lean-of-peak camp. If I'm not in a hurry, that's how I fly.

4 Shop For The Cheapest Fuel
Sadly, Mark Hanna's Fillup Flyer Fuel Finder has long since been shut down, but in this day of $6 (or even $7) avgas, there still are a few options for finding the cheapest fuel in your neighborhood. You can check two websites, www.airnav.com and and www.100ll.com, for current fuel prices in specific areas. While that doesn't mean you should fly out of your way to save a quarter a gallon, you may be able to realize some savings if cheap fuel is available somewhere along your route. Better still, these websites can alert you to the cheapest fuel on a given airport.

5 Fuel Intelligently
When you do find the least expensive place to buy, try to purchase fuel in the morning when temperatures are coldest and fuel is densest. (One pilot of a Piper Navajo, flying around the world pole-to-pole, arranged—at spectacular expense—to have his fuel supercooled at every stop to get more into the tank. He had to depart quickly after fueling, and use fuel from every tank to avoid having it warm up, expand and overflow.) You will, quite literally, get more bang for your buck, even if it's only a very slight amount. At $6/gallon, a half gallon saved on a 50-gallon fillup is worthwhile.

Similarly, remember to shake the wing occasionally during fueling to make certain there are no air bubbles. Once, in Reykjavik, Iceland, in 1989, flying the first Piper Mirage to Europe, I encountered a 10-gallon air bubble. When the airplane is definitely full, it's important to taxi out and run up on one tank, then, depart and climb on the opposite tank. Otherwise, the increased angle of attack in climb may cause one tank to overflow through the filler caps or the vent tubes.



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