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Run-up
The GEM makes on the ground engine diagnostics practical and easy.
Simultaneous display of EGT and CHT for all cylinders provides a detailed look at your engine during run-up. This illustration is typical of GEM display during run-up.
Magneto Check
EGT is often a better indicator of ignition problems that have been traditionally diagnosed by observing RPM drop during run-up. Switching to a single mag operation should cause uniform rise in EGT. All columns should rise by two bars or 50 degrees. If both mags don't produce a uniform result, you may have a serious ignition problem. If one spark plug or ignition wire on each mag is defective the single mag check would indicate an equal RPM drop on each. Such a double failure would go undetected. The Graphic Engine Monitor (TM) will not only identify the problem but pinpoint the affected cylinders.
Mixture Check
GEM displays a uniform EGT rise of all cylinders during mixture control check. An abnormally large exhaust gas temperature differential in one or more cylinders in fuel injected engines may warn of a fuel injector constriction.
Take-off
During critical phases of the flight, there is no time to scan or switch from cylinder to cylinder, memorize and interpret numbers to identify a problem.
The Graphic Engine Monitor will instantly identify a very serious class of problems that result from improper fuel or poor fuel distribution at high power settings. Pre-ignition could result in extensive engine damage in a few seconds if left unattended. A quick glance will show a dramatic nearly full scale rise in EGT of the affected cylinder. A significant rise in CHT will also be evident.
Leaning During Takeoff
Leaning during takeoff is desirable for best performance at high density altitudes. Use of the full rich mixture, intended for sea level takeoff, results in an over rich condition that seriously reduces engine performance at high altitudes. The Graphic Engine Monitor may be used to set the mixture using manufacturer's guidelines or by leaning to produce EGT indications typical of sea level takeoff.
Climb
During climb, your engine must run at maximum performance for an extended period of time. High power output and low airspeed are a challenging combination.
Leaning in Climb
Most aircraft benefit from mixture leaning during climb with less plug fouling, increased engine performance, smoother operation and better economy. As the aircraft ascends, the air density decreases causing an enrichment of the mixture. The same fuel/air ratio used for takeoff can be restored by observing GEM during the climb and leaning mixture to maintain EGT.
CHT Management
GEM makes it easy to monitor all CHT's simultaneously. One glance shows each cylinders actual CHT. Adjust cowl-flaps and airspeed as necessary to control CHT's.
Cruise
Leaning in Cruise
The goal of leaning in cruise is to select the optimum mixture for the engine at the current density altitude and power setting for best efficiency.
After establishing cruise power, use lean mode to find peak EGT. Press and hold the reset button for two seconds till the Annunciator blinks. Lean the mixture until a column blinks. The blinking identifies the leanest cylinder and that it has just gone past peak EGT. When you push the Reset Button to stop the blinking the instrument returns to Monitor Mode.
The mixture is now slightly too lean and should be enriched until the leanest cylinder's EGT drops one bar (25F°). This procedure sets the mixture to peak EGT or "best economy" setting.
For "best power" enrichen to produce a 3-4 bar (75° to 100°) temperature drop.
Normalize Mode
Once power mixture have been set for cruise, hold RESET and SELECT buttons to switch to normalize mode.
Descent
Mixture control during the descent. As the engine descends into denser air, EGT will rise unless Fuel-Flow is increased. Enrichen the mixture to maintain cruise EGT's.
CHT Management
The GEM's 25F° CHT bars give you immediate and obvious visualization of your engine temperature trend. Adjust power and airspeed to maintain CHT's in normal operating range.
Post Flight
The advanced GEM automatically datalogs every flight. Insight's powerful data-compression encryption system allow many flights to be stored in the GEM's on-board memory. Periodically transfer these valuable files from the GEM to your palmtop computer.
Simply turn on the palmtop computer, start the GEM software program, point it at the GEM and retrieve that vital information.
Once transferred to the palmtop computer, data can be viewed immediately or copied to a desktop/laptop computer for sophisticated graphical analysis.
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