J.P. Instruments EDM 740 Pilots Guide - Manual (Page 25)

For Your Safe Flight Page 25
LeanFind Procedure—General Explanation
Lycoming and Continental engines have established specific
restrictions on leaning that must be followed, such as
percentage of power, climb leaning, and TIT limits. Lycoming
recommends operation at peak EGT for power settings of
75% or lower, while Continental recommends operation at
peak EGT for power settings of 65% or lower. This guide is
not meant to supersede any specific recommendations of the
engine manufacturer or airframe manufacturer.
It is your responsibility to know your aircraft’s limitations.
Pre-leaning: The leaning process typically begins with ‘pre-leaning’ to
insure 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 ‘LOP’ 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).
Lean Find-Activation: When a 15° EGT rise occurs, LeanFind activates
(indicated by a cylinder I.D. box flashing over the number of the hottest
EGT). Remember: The LeanFind 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 word ‘LF’ in the right side (note: with the Fuel Flow option
installed, you will see the fuel flow instead of the word ‘LF’). This
information allows you to observe the EGT behavior throughout the
leaning process.