For Your Safe Flight ............................................. Page 31
Lean Find Procedure—General Explanation
Lycoming and Continental established specific restrictions on leaning
that must be followed, such as percent power, climb leaning, and TIT
limits. Lycoming recommends operation at peak of 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 EGTs decrease). Now enrich the mixture to achieve a 50°
drop on the hottest EGT. Ensure that all EGTs 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 ‘LOP’ for operating
Lean of Peak. Then the current mode will show up in the message bar
white on black, also you will see the alternate mode over the LF button.
You have 10 seconds to choose the alternate mode which will disappear
indicating your chosen mode white on black. To change, simply exit the
mode you are in and re-tap the LF button. 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).
Lean Find-Activation: When a 15° EGT rise occurs, Lean Find activates
(indicated by a cylinder I.D. box flashing over the number of the hottest
EGT). Remember: The Lean Find mode is not active until a cylinder
I.D. box is flashing. To show the progress of the leaning process, the
EDM now displays the hottest EGT in the left side of the digital display
and the fuel flow in the right side. This information allows you to observe
the EGT behavior throughout the leaning process.
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