For Your Safe Flight
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Expanded Leaning Procedures
Lean Of Peak mode:
During the ‘lean of peak’ process, the EDM hunts
for the last cylinder to peak. This is because, ultimately, you want to have
ALL cylinders operating on the lean side of peak. You will final adjust your
mixture to this cylinder. To provide a unique graphical depiction during
lean of peak operation, the columns become inverted after the first EGT
goes just below peak. Each EGT column then originates from the top of
the display and drops downward. As each subsequent EGT goes past
peak, its column will begin falling. The columns length depicts how far the
EGT has dropped below its original peak. In this mode, each segment is
5° F
. You will continue to lean until the last EGT peaks (note: never lean
to the point where the engine is running rough). When the last EGT
peaks, its respective column will flash and the word
RICHEST
appears
.
The scanner digital readout will now show the current temperature
difference from where peak EGT occurred and also the current fuel flow.
Note: if you hold the
LF
button, the display will show the captured peak
value of the ‘last EGT to peak’ and also the difference in fuel flow
between the first and last to peak (also known as the GAMI Spread). This
can be a good indication of how well your injectors are balanced (the
smaller the FF difference, the better the injector balance). Tapping
STEP
exits the lean find mode and automatic scanning resumes.
Leaning Turbocharged Engines
:
The leaning process for
turbocharged engines is by reference to the first EGT or TIT to
reach peak. Therefore you should use the Rich Of Peak mode. The
factory TIT red line may limit the leaning process, depending on
flight conditions. TIT red line is generally 1650°F to 1750°F. If TIT
exceeds red line (but not by more than 99°), the EDM will allow you
to continue leaning for one minute before a TIT alarm activates,
implying you should enrichen the mixture. NOTE: in some cases,
TIT can read approximately 100°F hotter than the hottest EGT. This
is because of unburned fuel in the exhaust igniting and is not
necessarily abnormal behavior. The reduced size of the JPI
Hastaloy-X-tip probes produce faster response and are more
accurate than the massive factory installed probes. Therefore a JPI
probe may read as much as 100°F higher than the factory installed
probe. However, the certified factory-installed gauge must be
obeyed as the limiting factor when adjusting your engine.