Cessna SKYMASTER 336 1964 Service Manual page 87

SECTION 7
FLAP CONTROL SYSTEM
TABLE OF CONTENTS
Page
FLAP CONTROL SYSTEM .........
Operational Checkout...........
Trouble Shooting ............
Removal, Installation and Repair of Flaps. .
Removal and Installation of Position
Transmitter .......
Adjustment of Position Transmitter ....
Removal and Installation of Down
Limit Switch .............
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7-1
7-3
7-6
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7-7
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7-1. FLAP CONTROL SYSTEM.
7-2.
The flap control system is electrically actu-
ated. The system consists of a flap switch, an elec-
tric motor and transmission, a down limit switch,
control cables, push-pull tubes, and three inter-
connected bellcranks in each wing. The transmis-
sion converts the rotary motion of the motor to the
push-pull motion needed to operate the flaps. The
transmission will freewheel at each end of its stroke,
but a down limit switch opens the flap motor circuit
just before freewheeling occurs in the down position.
Overrunning at intermediate flap settings is mini-
mized by a solenoid-released brake at the flap motor.
A three-position, momentary-on flap switch, spring-
loaded to the center "OFF" position, operates the
flap control system. The flap position indicator is
operated electrically by a position transmitter which
is linked mechanically to the left inboard flap bell-
crank. Refer to Section 8 for a description of the
flap/elevator trim interconnect system.
7-3. OPERATIONAL CHECKOUT OF THE FLAP
CONTROL SYSTEM.
a.
Operate flaps through full range of travel, ob-
serving for uneven or jumpy motion, binding, and
lost motion. Make sure flaps move together through
full range of travel.
b. Deliberately overrun motor at full up and full
down flap positions to make sure transmission is
freewheeling and down limit switch is operating.
c.
Check that flaps are not sluggish in operation.
It should take approximately 6 to 8 seconds for the
Adjustment of Down Limit Switch ....
Removal, Installation, and Repair of
Motor and Transmission Assembly. ..
Removal, Installation, and Repair of
Bellcranks ......
Replacement of Cables and Pulleys . . .
Rigging the Flap Control System ....
FLAP/ELEVATOR TRIM INTERCONNECT .
.
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.7-7
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flaps to extend or retract fully.
d.
Stop flaps at various settings during extension
and retraction to check that flaps do not coast.
e. Raise flaps and check that flap position indicator
reads 0°. Check each flap manually to see that it is
fully retracted.
NOTE
Each flap has four rollers which move in four
corresponding slots in the flap tracks. At
least one roller on each flap should contact
the end of its slot in the full up position. Only
the lower rollers are visible when the flaps
are up.
f. With the flaps full up, mount an inclinometer on
one flap and set to 0° . Lower flaps to the full down
position and check flap angle, which should be 30
°
,
± 2° for each flap.
NOTE
An inclinometer for measuring control surface
travel is available from the Cessna Spare
Parts Department. Refer to figure 6-5.
g. Open flap bellcrank access plates and attempt
to rock the bellcranks to disclose internal play.
h. Examine rollers and tracks for defective parts.
i. Check that raising the flaps from full down to
15° down will move the elevator trim tab from full
down to 10° down, + 2° , -0°.
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