Aero-Tips!
A good pilot is always learning -- how many times have you heard
this old standard throughout your flying career? There is no truer
statement in all of flying (well, with the possible exception of
"there are no old, bold pilots.")
Aero-News has called upon the expertise of Thomas P. Turner,
master CFI and all-around-good-guy, to bring our readers -- and us
-- daily tips to improve our skills as aviators. Some of them, you
may have heard before... but for each of us, there will also be
something we might never have considered before, or something that
didn't "stick" the way it should have the first time we memorized
it for the practical test.
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Aero-Tips 11.15.06
The single-engine service ceiling of a multiengine airplane is
the density altitude at which the airplane, at maximum weight in a
clean configuration (gear up, flaps up, inoperative engine's cowl
flaps closed and propeller feathered), is capable of climbing at 50
feet per minute. The published single-engine service ceiling (SESC)
for the most popular light twins is usually in the 3500-5000 foot
range... density altitude. Turbocharging usually raises the SESC to
12,000-15,000 feet.
Why should a multiengine pilot know the SESC of the airplane he
or she is flying?
Climbing up
Lose an engine on takeoff and you'll need to climb to a safe
altitude before you can maneuver to land. If the density altitude
at the departure airport is near the airplane's SESC and the
airplane is near maximum takeoff weight, it may not be possible to
make this safe climb to a maneuvering height. Or if there are
significant obstacles, the plane may be able to begin the climb but
won't have the power to outclimb the obstacle. The pilot of a
multiengine airplane would have no choice but to reduce power on
both engines and land nearly straight ahead if an engine quit under
these conditions. Attempting to climb out runs a very real risk of
colliding with terrain, or the temptation to attempt a turn at too
slow a speed and lose control of the aircraft.
Drifting down
Similarly, if an engine quits above SESC and the pilot flies at
"blue line" speed (maximum single-engine performance, Vyse) the
airplane will descend at the lowest rate of descent until it
reaches approximately SESC. Overflying mountains? Consider that
losing an engine in a twin may not present very many more options
that it would in a single-engine airplane…you should still
plan your route to provide an "out" to lower terrain or an
off-airport landing should an engine quit and the terrain below you
is above your SESC. Even a turbocharged twin could drift down to
ground level over the Rocky Mountains.
Weight
Airplane weight makes a big difference in single-engine
performance, so it will raise the SESC. Whenever possible, fly a
multiengine airplane at the lowest safe weight (that provides
sufficient fuel and reserves) to improve your SESC and
single-engine climb rate.
Aero-tip of the day: Look at the density
altitude, and consciously consider the relationship of takeoff and
terrain density altitude to your airplane's single-engine service
ceiling.