By AOPA Pilot Information Center staff
A top concern among AOPA members is the rising cost of avgas.
Although alternate fuel sources are being explored all over the world,
it will be some time before any of them have a direct impact on general
aviation.
You can minimize the hit to your wallet by practicing a few simple
fuel management techniques. Proper leaning combined with a lower
economy cruise setting and a cruise descent profile can result in
significant savings. Also, remember when you’re planning cross-country
flights to check FBO fuel prices in AOPA’s Airport Directory for the best deals.
Leaning
Leaving the mixture knob forward the entire flight is a big fuel
waster; not to mention that a full rich mixture at cruise power can
actually hurt some engines by causing rougher engine operation and
vibration. When properly done, leaning provides greater fuel economy,
smoother operation, and longer engine life.
Most engine manufacturers recommend leaning when operating at or
below 75-percent power. Above 75-percent power, the engine needs more
fuel to help keep it cool. Flying lean of peak is another step to
maximize your fuel savings. We’ll leave this decision up to you per the
manufacturer’s recommendations.
On longer cross-country flights, adjust the mixture to account for
pressure and weather changes and changes in altitude to maintain the
best economy fuel/air ratio. On the ground, at lower power settings,
you don’t have to worry about over-leaning. You can save fuel by
leaning aggressively during taxi.
Economy cruise
In combination with proper leaning techniques, consider bringing the
throttle lever farther back during cruise. A best-economy power setting
will provide the most miles for the gallon.
For instance, on a 200-nm cross-country flight in a Piper Archer,
bringing the power to 65 percent at best economy will save 3 gallons (6
gallons round trip) when compared to flying at 75-percent best power. AOPA’s Real-Time Flight Planner
shows the flight arriving nine minutes later when flying at 65 percent.
Time is valuable, but nine minutes is likely worth the $18 savings on
each leg of the flight.
Aircraft manufacturers provide best-power and best-economy fuel flow
based on proper leaning technique, so fly at the recommended power
setting. Simply leaning at a random power setting or only reducing
power without touching the mixture won’t yield the desired fuel burn
and may lead to serious fuel mismanagement.
Cruise descent
The most poorly managed segment of a flight is the descent. Instead
of flying straight to the airport traffic pattern, leave the power
setting where it is and prepare for a gradual 500-fpm descent to the
airport.
If, for example, you are cruising at 5,500 feet msl and want to
descend 3,500 feet to the traffic pattern altitude, start your descent
about 15 miles out to achieve a smooth cruise descent profile. No need
to touch the power, just lower the nose slightly with a trim
adjustment. The passengers in the back will also enjoy this smooth and
well-planned descent. Compared to the alternative practice of arriving
at the airport high and adding time in flight by circling down to the
proper altitude, you can save $6 in fuel costs.
Over the course of a 200-nm cross-country in the Archer, a pilot can
save a gallon by leaning when taxiing on the ground, 4 gallons in
flight with proper leaning and economy power settings, and another
gallon with a cruise descent.
At a total of 6 gallons and $6 per gallon, that’s $36 one way and
$72 round trip! Over the course of a dozen flights, investing a few
minutes of your time each leg of your trip will yield a savings of
hundreds of dollars. Not a bad way to fight back against inflated fuel
costs.