Engine Cooling; Propeller - Cirrus SR22 Pilot Operating Handbook

S 7: A
ECTION IRPLANE AND
P
ROPELLER

Engine Cooling

Engine cooling is accomplished by discharging heat to the oil and then to
the air passing through the oil cooler, and by discharging heat directly to
the air flowing past the engine. Cooling air enters the engine compartment
through the two inlets in the cowling. Aluminum baffles direct the
incoming air to the engine and over the engine cylinder cooling fins where
the heat transfer takes place. The heated air exits the engine compartment
through two vents in the aft portion of the cowling. No movable cowl flaps
are used.

Propeller

The airplane is equipped with a constant-speed, aluminum-alloy propeller
with a three-blade (78" diameter) propeller and governor.
The propeller governor automatically adjusts propeller pitch to regulate
propeller and engine RPM. The propeller governor senses engine speed by
means of flyweights and senses throttle setting through a cable connected
to the power (throttle) control lever in the cockpit. The propeller governor
boosts oil pressure in order to regulate propeller pitch position. Moving the
throttle lever forward causes the governor to meter less high-pressure oil to
the propeller hub allowing centrifugal force acting on the blades to lower
the propeller pitch for higher RPM operation. Reducing the power
(throttle) lever position causes the governor to meter more high-pressure
oil to the propeller hub forcing the blades to a higher pitch, lower RPM,
position. During stabilized flight, the governor automatically adjusts
propeller pitch in order to maintain an RPM setting (throttle position).
Any change in airspeed or load on the propeller results in a change in
propeller pitch.
7-38
S
YSTEMS
C D
IRRUS ESIGN
SR22
P/N 13772-006
Reissue A