Bailey Moyes 912 Dragonfly Maintenance Manual Download

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The tracking function may also be activated during climb or descent if desired. This is especially useful when
troubleshooting an intermittent problem. (It may be necessary to re-activate it during this phase of the flight to
account for the change in exhaust gas temperatures resulting from the new power setting.)

9.2

Leaning Functions (Not used with Rotax Engines)

For those with engines having adjustable mixture controls, the leaning functions are probably what
attracted you to the EIS, and you will not be disappointed. The EIS provides a bar graph page for those
who prefer this method, and a digital leaning page (identified by an “L” in the lower right corner). It is
recommended that you try both methods several times to determine which one is your favorite. In
general I prefer the digital leaning pages because they provide finer resolution (1 degree vs. 15 degrees
per bar graph segment), but this can be a matter of taste, as the bar graph page can make it easier to
visualize the EGTs.

9.2.1

Leaning with the Bar Graph

Using the bar graph page to lean is simply a matter of selecting the page, and adjusting the mixture
while observing the EGTs via the bar graphs. You may find it useful to customize the bar graph pages
to include information that could make it easier to lean, such as MAP, RPM, Fuel Flow, or the special
leaning functions, such as the First-to-Peak and EGPk.

9.2.2

Digital Leaning Page

To understand the digital leaning page, (the page with the “L” in the lower right corner), it is first
necessary to understand a few basic rules about the data shown on this page.

a)  When a cylinder is close to its highest EGT, the cylinder’s EGT is displayed.
b)  When a cylinder’s EGT is more than the amount specified on the “PEAK” setting below the highest
EGT, a negative value will be displayed showing how far this cylinder’s EGT is below its highest.
c) The highest EGT for a cylinder is continually updated. That is, whenever an EGT goes above the
internally stored value for the highest EGT, it is updated.
D) Selecting the “Save Lean Point?” page, and selecting “RESET”, will reset the highest EGT for
each cylinder to its current temperature.

In light of these rules, the typical procedure for leaning is as follows:

1) Select the digital lean page. This is the page with the “L” in the lower right corner.
2) Select the “Save Lean Point?” window, and select “RESET”. This resets the highest EGTs to the
current temperatures. You will note that immediately after doing this, the lean page will show all
positive values since all EGTs will be the newly stored highest. This also causes the First-to-Peak
indicator to reset to 0.
3) Slowly lean the engine. As you do, the EGTs should all increase (unless you have a cylinder
already operating past peak EGT, in which case it will decrease, indicating an engine problem exists).
As the EGTs increase, the instrument will be updating its internal highest for each cylinder, and the
numbers on the page will show EGTs.
4) As leaning continues, a cylinder will reach it peak EGT, and then begin to fall. Once it has fallen by
more than your setting for “PEAK” below its highest, the value shown on the screen will switch to a
negative number. The First-to-Peak function will now indicate which cylinder number was the first to
peak.
5) Typically the engine is then enriched to 50 degrees rich of peak (although this is a matter of your
preference). As you enrichen, all EGTs will drop, except those that were leaned past peak. The