S
ECTION
7: A
IRPLANE
AND
S
YSTEMS
C
IRRUS
D
ESIGN
E
NGINE
SR20
7-36
P/N 11934-005
The oil pressure sensor is mounted on the rear engine case and provides a
signal to the Engine Airframe Unit that is processed and transmitted to the
Engine Indicating System for display.
Manifold Pressure Gauge
Manifold pressure is shown in the upper center portion of the ENGINE
page as both a simulated pressure gauge and as a digital value. The gauge
pointer sweeps a scale range from 10 to 35 inches Hg in 1 inch Hg incre-
ments. The digital MAP value is displayed in white numerals below the
gauge. The manifold pressure sensor is mounted on the bottom of the
induction air manifold near the throttle body and provides a signal to the
Engine Airframe Unit that is processed and transmitted to the Engine Indi-
cating System for display.
Percent Power Gauge
Percent power is shown in the upper left corner of the ENGINE page as
both a simulated gauge and as a digital value. The percent power gauge
sweeps a scale marked from 0 to 100 percent in 5 percent increments. The
digital percent power value is displayed in white numerals below the gauge.
The display units calculate the percentage of maximum engine power
produced by the engine based on an algorithm employing manifold pres-
sure, outside air temperature, pressure altitude, engine speed, and fuel flow.
Engine Lubrication System
The engine is provided with a wet-sump, high-pressure oil system for
engine lubrication and cooling. Oil for engine lubrication is drawn from a
seven-quart capacity sump through an oil suction strainer screen, through
the remotely mounted oil cooler, and then directed to a full flow oil filter.
The oil cooler is equipped with a pressure relief and temperature control
valve set to bypass oil if the temperature is below 170 °F or the pressure
drop is greater than 18 psi. Bypass or cooled oil is then directed through a
pressure relief valve, and then through oil galleries to the engine rotating
parts and piston inner domes. Oil is also directed to the propeller governor
to regulate propeller pitch. The complete oil system is contained in the
engine. An oil filler cap and dipstick are located at the right rear of the
engine. The filler cap and dipstick are accessed through a door on the top
right side of the engine cowling.
Ignition and Starter System
Two engine-driven magnetos and two spark plugs in each cylinder provide
engine fuel ignition. The right magneto fires the lower right and upper left
spark plugs, and the left magneto fires the lower left and upper right spark
plugs. Normal operation is conducted with both magnetos (switch in
BOTH position), as more complete burning of the fuel-air mixture occurs
with dual ignition, and two magnetos provide redundancy. A rotary-type
Reissue A