Cessna 1969-1976 172 Series Service Manual page 140

9-7B. CLEANING, INSPECTION A N D REPAIR.
(Refer to figure 9- 3. )
a.
DO NOT remove bearing (16) from threaded
rod end (15) unless replacement of bearing is neces-
sary.
b.
Clean all component parts, except bearing (16),
by washing in Stoddard solvent o r equivalent. Do not
clean sealed bearing (16).
tions of damage such as stripped threads, cracks,
deep nicks and dents.
ed rod end (15) for excessive wear and scoring.
Dimensions of the p a r t s a r e
as follows:
c. Inspect all component p a r t s f o r obvious indica-
d. Check bearings (6 and 14), screw (9) and thread-
BEARING (6)
INSIDE DIAMETER O. 373" MIN.
INSIDE DIAMETER O. 380" MAX.
INSIDE DIAMETER
BEARING (14)
I
SMALL HOLE O. 248" MIN.
SMALL HOLE O. 253" MAX.
LARGE HOLE 0.373" MIN.
LARGE HOLE O. 380" MAX.
THREADED ROD END (15)
OUTSIDE DIAMETER
(SHANK) O. 242" MIN.
O. 246" MAX.
SCREW (9)
OUTSIDE DIAMETER O. 367'' MIN.
O. 370" MAX.
NOTE
Relative linear movement between internal
threaded screw (9) and bearing (14) should
be O. 004 to O. O10 inch
at
room temperature.
e. Examine threaded r o d end (15) and screw (9)
f o r damaged threads o r d i r t particles that may
impair smooth operation.
worn teeth.
f .
Check sprocket (5) for broken, chipped and/or
g. Check bearing (16) for smoothness of operation.
h. DO NOT attempt to r e p a i r damaged or worn
p a r t s of the actuator assembly. Discard all defective
items and install new p a r t s during reassembly.
9-7C. REASSEMBLY. (Refer to figure 9-3.)
new parts during reassembly:
a.
Always discard the following items and install
1. Groov-Pins (8 and 10).
2. O-Ring (13).
3. Nuts (2).
b. During reassembly, lubricate collars (7), screw
(9) and threaded rod end (15) in accordance with pro-
cedures outlined in Section 2.
c.
Install collar (7) and bearing (6) on screw (9).
d. Press sprocket (5) into the end of screw (9),
e.
Insert screw (9), with assembled parts, into
align groov-pin holes and install new groov-pins (8).
housing (12) until bearing (6) is flush with end of
housing.
NOTE
When inserting screw (9) into housing (12),
locate the sprocket (5)
at
the end of housing
which is farther away from the groove for
retaining ring (11).
0
The bearings (6 and 14) a r e not pre-drilled
and must be drilled on assembly. The groov-
I
pins (10)
are
1/16 inch in diameter, there-
fore, requiring a 1/16 (O. 0625) inch drill.
f . With bearing (6) flush with end of housing (12),
carefully drill bearing so the drill will emerge
from the hole on the opposite side of housing (12).
DO NOT ENLARGE HOLES
IN
HOUSING.
g. Press new groov-pins (10) into pin holes.
h. Insert collar (7), new O-ring (13) and bearing
i.
Complete s t e p s
"f"
and "g" for bearing (14).
j .
If
a
new bearing (16) is required,
a
new bearing
I
(14) into opposite end of housing (12).
may be pressed into the boss. Be s u r e force b e a r s
against the outer r a c e of bearing.
k. Screw the threaded r o d end (15) into screw (9).
1. Install retaining r i n g s (ll), i f they were re-
moved.
m. Test actuator assembly by rotating sprocket (5)
with fingers while holding threaded r o d end (15).
The threaded rod end should travel in and out smooth-
ly, with no indication of binding.
paragrpah 9-7.
n. Reinstall actuator assembly in accordance with
9-7D. TRIM TAB FREE-PLAY INSPECTION.
a.
Place elevators and t r i m tab in the neutral posi-
tion.
b. Using moderate pressure, move the t r i m tab
trailing edge up and down by hand to check free-play.
c. A maximum o f . 131" (total motion up and down)
measured
at
the t r i m tab trailing edge is permissible.
d. If the t r i m tab free-play is less than .131", the
system is within prescribed limits.
e. I f the t r i m tab free-play is more than .131",
check the following i t e m s for looseness while moving
the t r i m tab up and down.
assembly attachment f o r looseness.
threaded
rod end attachment for looseness.
f o r looseness in the actuator assembly.
e- 1 and e- 2, repair by installing new parts.
e-3, refer to paragraphs 9-6 through 9-7C.
9-8. TRIM TAB CONTROL WHEEL. (Refer to fig-
u r e 9-1.)
I
1. Check push-pull channel to trim tab horn
2. Check push-pull channel to actuator assembly
3. Check actuator assembly threaded rod end
If looseness is apparent while checking steps
If looseness
is
apparent while checking step
f .
g.
9-9. REMOVAL AND INSTALLATION.
a. Relieve cable tension a t turnbuckle (8).
Position a support stand under tail tie-down
ring to prevent tailcone from dropping while
working inside.
9-6 Change 3