Cessna 1969-1976 172 Series Service Manual page 117

SECTION 7
WING FLAP CONTROL SYSTEM
TABLE OF CONTENTS Page
WING FLAP CONTROL SYSTEM
. . . . . . .
7-1
Description
. . . . . . . . . . . . . .
7- 1
Operational Check
. . . . . . . . . . .
7- 1
Trouble Shooting
. . . . . . . . . . . .
7- 2
Flap Motor and Transmission Assembly
.
7-3
Removal and Installation.
. . . . . .
7-3
Drive Pulleys
. . . . . . . . . . . . .
7-
3
Removal and Installation
. . . . . .
7-3
Repair
. . . . . . . . . . . . . .
7 -8
Repair.
. . . . . . . . . . . . . .
7-
3
I
7-1. WING FLAP CONTROL SYSTEM. (Refer to
figure 7- 1. )
7-2. DESCRIPTION. The wing flap control system
is comprised of
an
electric motor and transmission
assembly, drive pulleys, push-pull rods, cables,
pulleys and
a
flap position indicator. Power from the
motor and transmission assembly is transmitted to
the flaps by a system of drive pulleys, cables and
push-pull rods. Electrical power to the motor is con-
trolled by
a
3-position switch mounted on the instru-
ment panel. The flap position indicator
is
calibrated
to show degrees of extension.
7-3. OPERATIONAL CHECK.
a. Operate f l a p s through their full range of travel,
observing for uneven or jumpy motion, binding and
lost motion in system. Ensure flaps a r e moving to-
gether throngh their full range of travel.
00804 WHEN NOT MODIFIED IN ACCORDANCE WITH
FIGURE 7-2, SHEET 3. Attempt to overrun travel
e x t r e m e s and check f o r transmission free-wheeling
at
full up and full down positions.
c . BEGINNING WITH AIRCRAFT SERIALS 17259905
AND F17200805 AND ALL AIRCRAFT MODIFIED IN
I
ACCORDANCE WITH FIGURE 7-2, SHEET 3. Check
b. THRU AIRCRAFT SERIALS 17259904 AND F172-
I
Flaps
. . . . . . . . . . . . . . . . .
7-8
Removal and Installation
. . . . . .
7-8
Repair
. . . . . . . . . . . . . .
7 -8
Flap Position Transmitter
. . . . . . .
7 -8
Removal and Installation
. . . . . .
7-8
Adjustment
. . . . . . . . . . . .
7 -8
Cables and Pulleys
. . . . . . . . . . .
7-8
Removal and Installation
. . . . . .
7-8
Rigging
. . . . . . . . . . . . . . . .
7 -8
for positive shut-off of motor
at
the flap travel ex-
t r e m e s , FLAP MOTOR MUST STOP OR DAMAGE
WILL RESULT.
d. Check that flaps a r e not sluggish in operation.
In flight
at
100 mph, indicated airspeed, flaps should
fully extend in approximately 9 seconds and r e t r a c t
in approximately 5 seconds. On the ground, with en-
gine running, the flaps should extend o r r e t r a c t in
approximately 6 seconds.
flap and set to 0". Lower flaps to full DOWN posi-
tion and check flap angle
as
specified in figure 1- 1.
Check approximate mid-range percentage setting
against degrees
as
indicated on inclinometer. Repeat
the same procedure f o r the opposite flap.
I
e. With flaps full UP, mount an inclinometer on one
NOTE
An inclinometer f o r measuring control sur-
face t r a v e l
is
available from the Cessna
Service
Parts
Center. Refer to figure 6-4.
f .
Remove a c c e s s plates adjacent to flap drive pul-
l e y s and attempt to rock pulleys to check for bearing
wear.
g. Inspect flap r o l l e p and t r a c k s for evidence of
binding and defective parts.
Change 1 7-1