For Your Safe Flight
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Lean Find Procedure
—General Explanation
Lycoming and Continental have established specific restrictions on
leaning that must be followed, such as percent power, climb leaning,
and TIT limits. Lycoming recommends operation at peak EGT at 75%
or less power only. Continental recommends operation at peak EGT
at 65% or less power only. This guide does not supersede specific
recommendations of the engine or airframe manufacturer
. It is your
responsibility to know your aircraft’s limitations.
Pre-leaning:
The leaning process typically begins with ‘pre-leaning’ by
leaning the mixture until you see the hottest cylinder peak. Ensure all
cylinders are operating rich of peak EGT (note: you can optionally
activate ‘Normalize’ - hold LF until
NRM
appears - making it easier to
confirm all EGT’s decrease). Now enrichen the mixture to achieve a 50°
drop on the hottest EGT. Insure that all EGT’s decrease. Wait one minute
to allow temperatures to stabilize.
Lean Find
-
Initiation:
Initiate the EDM leaning mode by tapping the LF
button. Note that the EDM displays its current leaning mode momentarily:
‘
ROP’
for operating Rich of Peak or ‘
L
OP’
for operating Lean of Peak. To
change, simply hold STEP and LF until the display shows the other
mode. The EDM is now waiting for a 15° rise on any EGT (this feature
significantly reduces false peaks). Lean the mixture
without pausing
to
achieve about a 10 deg per second change. With a Vernier mixture
control, turn the knob about a quarter turn every second. With a non-
Vernier or quadrant mixture control, lean slowly and smoothly about 1/16
inch every five seconds (note: leaning accurately with a quadrant system
is difficult due to its mechanical linkage).
