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CESSNA AIRCRAFT COMPANY
FOR TRAINING USE ONLY
MODEL 152
7-16
IGNITION-STARTER SYSTEM
Engine ignition is provided by two engine-driven magnetos, and two spark plugs in each cylinder. The
right magneto fires the lower right and the upper left spark plugs, and the left magneto fires the lower
left and upper right spark plugs. Normal operation is conducted with both magnetos due to the more
complete burning of the fuel-air mixture with dual ignition.
Ignition and starter operation is controlled by a rotary type switch located on the left subpanel. The
switch is labeled clockwise, OFF, R, L, BOTH, and START. The engine should be operated on both
magnetos (BOTH position) except for magneto checks. The R and L positions are for checking purposes
and emergency use only. When the switch is rotated to the spring-loaded START position, (with the
master switch in the ON position), the starter contactor is energized and the starter will crank the
engine. When the switch is released, it will automatically return to the BOTH position.
AIR INDUCTION SYSTEM
The engine air induction system receives ram air through an intake in the lower portion of the engine
cowling. The intake is covered by an air filter which removes dust and other foreign matter from the
induction air. Airflow passes through the filter enters an airbox. After passing through the airbox,
induction air enters the inlet in the carburetor which is under the engine, and is then ducted to the
engine cylinders through intake manifold tubes. In the event carburetor ice is encountered or the intake
filter becomes blocked, alternate heated air can be obtained from the muffler shroud through a duct to
a valve, in the airbox, operated by the carburetor heat control on the instrument panel. Heated air from
the muffler shroud is obtained from an unfiltered outside source. Use of full carburetor heat at full
throttle will result in a loss of approximately 150 to 200 RPM.
EXHAUST SYSTEM
Exhaust gas from each cylinder passes through riser assemblies to a muffler and tailpipe on the right
side of the engine. The muffler is constructed with a shroud around the outside which forms a heating
chamber for carburetor heat and cabin heater air.
CARBURETOR AND PRIMING SYSTEM
The engine is equipped with an up-draft, float-type, fixed jet carburetor mounted on the bottom of the
engine. The carburetor has an idle cut-off mechanism and a manual mixture control. Fuel is delivered
to the carburetor by gravity flow from the fuel system. In the carburetor, fuel is atomized,
proportionally mixed with intake air, and delivered to the cylinders through intake manifold tubes. The
proportion of atomized fuel to air is controlled, within limits, by the mixture control on the instrument
panel.
For starting, the engine is equipped with a manual priming system. The primer is actually a small pump
which draws fuel from the fuel strainer when the plunger is pulled out, and injects it into the cylinder
intake ports when the plunger is pushed back in. The plunger knob, on the instrument panel, is
equipped with a lock and, after being pushed full in, must be rotated either left or right until the knob
cannot be pulled out.
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