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.") It's part of what makes aviation
so exciting for all of us... just when you think you've seen it
all, along comes a scenario you've never imagined.
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, and as
representatives of the flying community. 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.
It is our unabashed goal that "Aero-Tips" will help our readers
become better, safer pilots -- as well as introducing our
ground-bound readers to the concepts and principles that keep those
strange aluminum-and-composite contraptions in the air... and allow
them to soar magnificently through it.
Look for our daily Aero-Tips segments, coming each day to you
through the Aero-News Network. Suggestions for future Aero-Tips are
always welcome, as are additions or discussion of each day's tips.
Remember... when it comes to being good pilots, we're all in this
together.
Aero-Tips 02.03.06
In Aero-Tips 1/8/06 we learned
that the peak, or highest Exhaust Gas Temperature (EGT) is the
benchmark for all mixture leaning. But how can we use this
information?
Cylinder Head Temperature
Cylinder Head Temperature (CHT) is probably the most critical
aircraft engine indication for engine longevity (oil temperature
and pressure are more important for short-term engine health). Like
other parameters, CHT follows a temperature curve relative to the
EGT indication. Specifically, from a very rich mixture setting CHT
increases as mixture is leaned, hitting peak CHT
at about the point where EGT is 40°F rich of its own peak.
Perhaps more clearly:
- Carefully lean to find peak EGT.
- Note the indicated temperature (as we’ve said before, the
actual temperature isn’t important; we’re discussing
temperature relative to peak).
- Enrichen the mixture (add fuel) until the EGT is 40°F
cooler than it was at peak.
You’re now at the maximum CHT for the power setting
you’ve chosen.
There is NO advantage to running at peak
CHT. If a cylinder is capable of running so hot that
it wears excessively, this is the mixture setting that does the
most HARM. The CHT curve is fairly flat near its peak, meaning that
too-hot CHTs may result from leaning near this peak
point—including the 25°F rich-of-peak EGT setting
virtually all Pilots Operating Handbooks recommend. To avoid this
potentially damaging (at least at high power settings) CHT range,
lean either much richer or much leaner than the
40°F EGT point…whatever it takes to keep CHTs under
control.
We’ll continue to investigate engine temperature
management in future Aero-Tips. For more information now, see www.advancedpilot.com.
Aero-tip of the day: Know what effect mixture
settings have on CHT, and manage your engine to avoid excessive
cylinder heat.