Late Model Systems • 5
System descriptions are given first for Late Model, and then differences only for
Early Model.
Engine
The 172 R and S models are equipped with a Lycoming, 4 cylinder, normally
aspirated, fuel injected, 360 cubic inch, horizontally opposed, air cooled, direct
drive IO-360-L2A engine. The R model produces 160 HP @ 2400 RPM, and the
S model and R Model with Cessna 72-01 engine modification produces 180 HP
@ 2700 RPM. Ignition is provided by 2 magnetos on the back of engine which
provide spark to 8 spark plugs (2 per cylinder). The engine has an 8 quart oil
sump. ATP minimum oil quantity for takeoff is 6 quarts.
Propeller
The engine drives a McCauley, 75 inch (R- Model) 76 inch (S- Model and R with
Modification), 2 blade, all metal, fixed pitch propeller.
Vacuum System
Two engine-driven vacuum pumps are located on the back of engine, providing
vacuum to the attitude and heading gyros, and have a normal operating
range 4.5-5.5 inches of mercury. Failure of a vacuum pump is indicated by an
annunciator panel light. In most circumstances, failure of one pump alone will
not cause the loss of any instruments because the remaining pump should
handle the entire vacuum demand.
Landing Gear
The landing gear is a fixed, tricycle type gear consisting of tubular spring steel
providing shock absorption for the main wheels, and an oleo (air/oil) strut
providing shock absorption on the nose wheel. The nose strut extends in flight,
locking it in place. The nose wheel contains a shimmy damper which damps
nose wheel vibrations during ground operations at high speeds. The nose
wheel is linked to the rudder pedals by a spring loaded steering bungee which
turns the nose up to 10° each side of center. Differential braking allows for up to
30° of steering either side of center.
SECTION 2
Aircraft Systems
Late Model (R&S)