Electronics International US-8A - Manual (Page 19)

Operating Information
For the Ultimate Analyzer to diagnose problems it is important the limits be set properly. The golden rule for
setting the limits on the Ultimate Analyzer is “No Red Light During Take-Off, Climb or Cruise.” If your
engine is operating properly and you’re getting a red light, see “Selecting the Proper Limits” section of this
manual.
4. Climb:
Leave the Ultimate Analyzer in the scan operating mode during the entire climb. The Ultimate Analyzer will
automatically diagnose your engine during the climb. A red “Temp Prob” light will alert you if the Ultimate
Analyzer detects a problem. One situation that may occur on non-turbo charged aircraft during a climb is a
low EGT warning. As the aircraft climbs the air gets thinner and the engine will run richer. When this
happens the EGT temperatures will drop and may violate the Lower EGT Limit. Many Ultimate Analyzer
pilots look for this warning to enable them to properly lean during the climb. If you use this method, do not
allow the EGT temperatures to exceed 1300’F for throttle settings above 75% power. Refer to the engine
and aircraft operator's manual for proper leaning information for your aircraft.
5. Cruise:
In cruise you will want to lean your engine. A rich running engine wastes fuel needlessly and tends to run on
the rough side, thereby creating vibration, which causes deterioration of engine accessories and engine
mounts. Also, proper leaning at cruise and during descent means less spark plug fouling, longer life for the
plugs, reduced maintenance costs and a considerable fuel savings. Furthermore, good leaning techniques
result in cleaner combustion chambers with fewer lead salt deposits on the pistons and exhaust valves. Under
certain conditions, these deposits invite preignition and higher maintenance costs. Proper leaning at cruise
during cool or cold weather aids in raising engine and oil temperatures to desirable minimums in order to
evaporate the water and acids out of the oil. Water and acids attack the insides of an engine, causing rust and
corrosion.
To properly lean your engine perform the following steps:
A) Rough Leaning: Set the Ultimate Analyzer in the Manual Operating Mode and push the “Peak”
button below the EGT display. This feature only functions if you are set up to monitor all of your
EGT's. Adjust the mixture control from the full rich position to a leaner setting that results in a slight
drop in engine RPM or to a setting near lean, as dictated by experience. The mixture control should be
left at this setting until the EGT’s stabilize. It will take about 20 seconds for the temperatures to stabi-
lize within 1`F. This lag is due to the combustion walls and piston domes increasing in temperature and,
therefore, affecting the combustion and exhaust gas temperatures. To correctly lean an engine you must
wait for the engine to thermally stabilize. Less sensitive gauges will not pick up these subtle changes,
which are important in leaning and diagnosing problems.
B) Precision Leaning: Again press the “Peak” button on the Ultimate Analyzer to find the hottest EGT
cylinder. This cylinder may be different than the one you started with. This is the cylinder on which
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Operating the Ultimate Analyzer in Your Aircraft