Rear Engine Cooling Fan; Engine Mounts - Cessna SKYMASTER 336 1964 Service Manual

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Figure 10-5. Rear Cowl Flap Rigging (Sheet 2 of 2)
n. Turn on battery switch and operate to "OPEN"
and "CLOSED" positions, checking for interference
between torque tube and linkage.
o. Operate to the "CLOSED" position and turn off
battery switch.
p. Adjust push-pull rods at cowl flap to align at-
taching holes while cowl flap is closed (faired with
upper cowl), and install rods and springs. Check
that the distance between cowl flap leading edge and
fuselage is at least 3.35 inches at centerline, and
readjust push-pull rods if necessary.
q. Check that all rod ends and clevis ends have suf-
ficient thread engagement, all jam nuts are tight,
and all safeties are installed, then reinstall all parts
removed for access.
10-37. REAR ENGINE COOLING FAN.
10-38. A multi-blade, statically balanced, axial flow
cooling fan is concentrically mounted between the en-
gine and propeller at the circular opening of the rear
cowling. The fan decreases air pressure beneath the
engine to increase velocity of the air admitted through
the cowl flap opening above the engine. Appropriate
baffles route the cooling air down through the cylinder
cooling fins, out through the fan, to provide optimum
cooling of the engine.
10-39. REMOVAL AND REPLACEMENT OF THE
REAR COOLING FAN. The rear cooling fan is freed
by removal of the propeller (refer to paragraph 12-5).
Before removal, the fan and associated plates and
fairings should be marked so they can be reinstalled
in exactly the same positions.
No disassembly of
the fan itself is permitted. Figure 10-6 maybe used
as a guide for removal and installation. When parts
are replaced, or if relative positions of parts can-
not be determined, static balance of the assembled
parts must be checked. Section 16 gives balancing
requirements as well as repairs permitted. Inspect
the rear engine cooling fan at each 50-hour inspection
for evidence of cracks at the base of each blade on
the engine side of the fan. Remove engine cowling
and clean the fan blades prior to inspection so that
oil streaks are not mistaken for cracks. It is not
necessary to remove the fan to make this inspection.
Cracked cooling fans must be replaced before the air-
plane is returned to service.
10-40. ENGINE MOUNTS (TUBULAR).
10-41.
The engine mounts are composed of sections
of steel tubing welded together and reinforced with
gussets. Each engine mount forms a truss structure,
fastened to the fuselage at four points, which supports
its engine through a cradle arrangement.
Both en-
gines are attached to the engine mounts with shock
mount assemblies which absorb engine vibrations.
The front engine mount includes provisions for shock
mounts which support the free-floating front cowl,
and the nose gear shock strut is attached to the front
engine mount structure.
The rear engine mount is
so designed that a severe forward impact, as in a
crash landing, will cause the rear engine to fall be-
low the cabin.
10-42. REMOVAL AND INSTALLATION OF ENGINE
MOUNTS. Removal of either engine mount is accom-
plished by removing the engine, then removing the
mount from the fuselage.
Front engine mount bolts
are installed with their heads forward. When tighten-
ing, torque the bolts to 190-225 lb-in. Rear engine
mount bolts are installed with the nuts aft. When
tightening, torque the nuts to 160-190 lb-in.
10-43. REPAIR OF ENGINE MOUNTS. Refer to
Section 16 for engine mount repairs.
The engine
mount should be painted with heat-resistant black
enamel after welding, or whenever the original
finish has been removed.
10-17
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