LeanFind Mode (730/830 used as example below – EDM-700/800 similar.)
The EDM supports two methods of leaning; Rich Of Peak (ROP)and Lean Of Peak(LOP). Note: you can set the power-up default to LOP or ROP in the Pilot Program Mode but easily change modes during flight. During traditional Rich Of Peak leaning, you’ll finalize the mixture to about 20 to 80° rich of peak (depending on engine operating requirements). However, with the advent of closely balanced injectors (such as GAMI), it is possible to set the mixture lean of peak—thus saving fuel and running the engine cooler. Teledyne Continental recommends lean of peak for the Malibu. Both Rich Of Peak and Lean Of Peak processes are described in detail in this manual.
Upon reaching cruise configuration, use the LeanFind mode to identify the correct cylinder to reach peak EGT (for rich of peak this is the FIRST to peak, for lean of peak this is the LAST to peak). To change from one method to the other, just after activating LeanFind, hold STEP and LF and the other method will be momentarily shown: ROP or LOP. Release buttons after other method appears.
The following charts provide step by step guidelines in leaning your engine, for both rich of peak and lean of peak modes:
Rich of Peak leaning is as simple as:
- Pre-lean your mixture.
- Tap the LF button (verify ROP appears).
- Lean mixture until LEANEST flashes (peak found).
- Enrichen to the desired value ‘Rich Of Peak’.
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R
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Procedure
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Scanner Example
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Comments
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1
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Establish cruise at 65 to 75% power.
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2
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Pre-lean the mixture to 50°F estimated rich of peak on any EGT: _________°F.
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EGT 1490 CHT 370
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*See ‘Pre-leaning’
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3
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Wait one minute
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Let engine stabilize.
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4
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Tap the LF button
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ROP
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Start LeanFind (if LOP appears hold STEP & LF until ROP appears)
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5
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Lean the mixture at approx. 10°/secondwithout pausing. (cylinder I.D. box flashes when a EGT rises 15°F)
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EGT 1520 LF
(Without FF)
– or –
EGT 1520 FF 13.8
(With FF)
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Flashing cylinder I.D. box identifies the hottest EGT and that an EGT has increased at least 15°F which arms the EDM to now look for first EGT to peak.
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6
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Stop leaning when
a column begins flashing. You will seeLEANESTfor one second, followed by:
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EGT 1545 SET
(Without FF)
– or –
EGT 1545 FF 12.4
(With FF)
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Flashing cylinder I.D. box ANDits column indicates leanest cylinder. (SET means Set the mixture.) Due to thermal inertia this will usually be about -15°F down the lean side of peak.
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7
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If you hold LF, peak EGT will be displayed while the LF button is held down.
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EGT 1560 PK
(Without FF)
– or –
EGT 1560 FF 12.9
(With FF)
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Captured peak EGT value (plus peak FF, if FF equipped) is displayed.
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8
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If you tap LF, the difference from peak EGT is shown. Tap again to return to the peaked EGT value.
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EGT -90 SET
(Without FF)
– or –
EGT -90 FF 13.4
(With FF)
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A useful mode for enrichening the mixture to desired degrees below peak. Just set to desired value – no math required! NOTE: Unit remembers view last used.
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9
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Slowly enrich mixture noting that EGT is returns to peak then drops. Stop enriching at the desired EGT. ‘Peak’: best Econ. ‘ROP’ target: best power.
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EGT 1560 SET
(PEAK)
EGT 1460 SET
(100º RICH OF PEAK)
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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 untilNRM 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.
Lean Find-Rich Of Peak Detection: Eventually, one cylinder will reach peak before any of the other cylinders. The EDM will determine this automatically. The EDM will indicate success in finding a peak by displaying the word LEANEST for two seconds and flashing the peaked EGT column. The Scanner® Information Area will also display the current value for the peaked EGT on the left, and the word SET on the right (or fuel flow value, if so equipped), for final adjustment of the mixture. The peak EGT value encountered during leaning is remembered by the EDM and can be displayed by holding the LF button during Lean Find Mode.
Lean Find-Finalizing the Rich Of Peak Mixture: You may now enrichen the mixture to operate at peak or continue enriching to a value of your choice (typically between 50 to 100° rich of peak for best power), consistent with the procedures defined in your aircraft and/or engine manual. Note: tap LF to see the current difference from the peak temperature. This is handy for finalizing mixture. Tapping STEP exits the lean find mode and automatic scanning resumes.
