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cylinders which were leaned past peak with first increase, and then decrease. The key to making it
simple, it to ignore all but the first to peak (the first to go negative). Use this cylinder to adjust mixture
to your desired setting (such as 50 degrees rich of peak).
Note that the leaning page is typically most meaningful while leaning, and for several minutes after
leaning. This is because of the effect of the highest EGT always being re-computed. Consider for
instance the scenario where you leaned a hour ago, but during the last hour you made some power
changes, encountered turbulence, changed altitude, or similarly caused the EGTs to reach new highs.
Once re-stabilized in cruise, even if the EGTs returned to the same temperatures they were at
immediately after leaning, the new highs for the EGTs stored internally will cause the lean page to
show different values than that showed immediately after leaning.
The “PEAK” setting allows you to specify how sensitive the instrument will be to detecting the first
cylinder to go past peak. As you lean, an exhaust gas temperature could go down a few degrees during
the leaning process due to varying engine loads (turbulence) or other factors. The instrument will not
declare a cylinder to be the first to peak unless it is the first cylinder to fall by the amount specified in
the “PEAK” setting from the maximum temperature that cylinder has achieved.
9.2.3
Special leaning functions
Two special functions are provided that are helpful when leaning. These functions are selectable on the
user-definable pages, and are provided on the factory default bar graph pages.
9.2.4
First-Cylinder-to-Peak (FRST2PK)
This function indicates which cylinder peaked first during leaning. This function will display 0 after
selecting “RESET” from the “SAVE LEAN POINT?” page. It will remain as 0 until a cylinder has
peaked (fallen by more than the “PEAK” setting from its highest EGT). Once the first cylinder has
peaked, this function will show which cylinder was the first to peak. It will not change until “RESET”
is selected from the “SAVE LEAN POINT?” page.
9.2.5
EGPk (First-Cylinder-to-Peak Leaning Status)
This function displays the leaning page information for whichever cylinder was the First-to-Peak. The
function will display 0 until a cylinder peaks, and then displays either the current exhaust gas
temperature for this cylinder if it is currently less than the “PEAK” setting of its maximum EGT, or the
number of degrees below the peak EGT detected.
Note that it is perfectly feasible (depending on your leaning preference) to lean the engine using only
the EGPk display. Using this display alone, you can lean until the first cylinder peaks, and enrichen
(or not) as desired.
9.3
Shock Cooling Detection
The cylinder head rate-of-cooling (in degrees/minute) for the cylinder head temperature that is
dropping the fastest is provided by this function. This information is provided on a labeled page above
the “CRate” label. A maximum cylinder head rate-of-cooling limit may also be set. Consult your
engine manual to see if such a limit is published for your engine. If no limit is published, you may
determine a limit by trial and error. While not all agree that shock cooling of the cylinders is a real
problem, there is no doubt that internal stresses in the cylinders can be reduced by avoiding shock
cooling. In addition, some of our customers with glider towing operations are convinced that shock
cooling can cause cylinder cracking.
Summary of Contents for 912 Dragonfly
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Page 79: ...Page 78 Wiring1 jpg Drawing 28a ...
Page 80: ...Page 79 Wiring2 jpg Drawing 28b ...
Page 81: ...Page 80 elecLights jpg Drawing 28c ...
Page 83: ...Page 82 Drawing 29 ...
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Page 92: ...Page 91 Appendix B Brakes Manual for BX1320 BX1000 Appendix B Page 1 ...
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Page 104: ...Page 103 Figure 1a Description of Display Pages ...
Page 105: ...Page 104 Figure 1b Description of Display Pages ...
Page 138: ...Page 137 Appendix C EIS 4000 912 914 ...
Page 139: ...Page 138 Appendix C EIS 4000 912 914 ...
Page 140: ...Page 139 Appendix C EIS 4000 912 914 ...
Page 141: ...Page 140 Appendix C EIS 4000 912 914 End Appendix C ...
Page 155: ...Page 154 Appendix E2 Powerfin Prop Page 2 ...
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