Rockwell Commander 112 - Elevator Trim Tabs

ROCKWELL
COMMANDER
112/B/TC /TCA
MAINTENANCE MANUAL
SECTION VII
FLIGHT CONTROLS
stalled and all jam nuts are tightened. Replace all
parts removed for access.
ELEVATOR TRIM TABS
Controllable trim tabs, located on the inboard trailing
edge of each elevator, are operated by an elevator
trim tab control wheel installed in the center console
(see Figure 7-10). A portion of the trim tab control
wheel extends through the center console, and when
rotated, actuates the trim tab through a mechanical
linkage conSisting of cables, chains, jackscrew as-
sembly and push rods that attach to the trim tab.
Turnbuckles between fuselage stations 179. 98 and
262.75 are utilized for rigging and adjusting cable
tensions. An indicator strip, visible through a slot
in the console, indicates neutral, nose up or nose
down positions.
REMOVAL OF ELEVATOR TRIM CONTROL WHEEL
AND CABLES.
a. Remove front seats, rear seat and floorboard
assembly, console covers and aft baggage curtain
from airplane.
b. Relieve tension and disconnect cables at turn-
buckles (see Figure 7-9).
c. Remove cable guards from elevator trim
pulleys located in aft part of fuselage.
d. Pull left, or nose down cable, down far
enough to gain access to point where cable end is
attached to elevator trim control chain and disconnect
cable. Repeat for right, or nose up cable.
e. Remove cable guard from pulley cluster loca-
ted at station 179.98.
f. Remove screws, nuts and washers attaching
phenolic guide blocks to aileron pulley bracket, loca-
ted aft of main spar. Remove guide blocks.
g. Remove cable guard from pulley cluster loca-
ted beneath trim wheel.
h. Remove trim wheels by disconnecting eleva-
tor trim indicating strip and removing cotter pins
from trim wheel supports.
i. Lift trim wheel up, draw cables out through
console, unwrap cable s from trim wheel drum and
pull cable swage pin out of drum.
INST ALL AT ION OF ELEVATOR TRIM CONTROL
WHEEL AND CABLES.
a. Determine which of two elevator trim cable
ends has right hand threads. This portion of cable
must be used as right elevator trim cable.
b. Find center of cable, (where swage pin is
installed) and insert swage pin into hole in trim
wheel drum (see Figure 7-10).
c. Hold trim wheel up and wrap right portion
of cable clockwise, four wraps, around drum (see
Figure 7-10. Wrap tape around cables to temporar-
ily hold in plac e.
d. Wrap left portion of cable, counterclockwise,
four wraps around drum (see Figure 7-10). Wrap
tape around cables to temporarily hold in place.
e. Install trim wheel and insert cotter pins
through supports.
f. Route cables around trim cable pulleys as
depicted in Figure 7-10 and back through console.
g. Feed cables between aileron pulley bracket
and install phenolic guide blocks.
h. Route cables under baggage compartment
floor and through pulleys at station 179.98.
L With elevator trim tab neutralized, ends of
trim chain should be even. Connect two rear trim
cable s to trim chain. Be sure that right rear cable
has left hand threads on end that screws into turn-
buckle.
j. Be sure cables are not crossed and are in
proper pulley grooves, then clamp trim wheel in
neutral position. (Neutral position is with swage
pin straight up, and four cable wraps on each side).
With elevator trim tab in neutral pOSition, connect
cables at turnbuckles. Adjust turnbuckles to obtain
correct tension on each cable. (Refer to Figure
7 -13 for correct tenSion).
k. If elevator trim indicator strip has been re-
moved, wrap end around trim wheel shaft, counter-
clockwise, three wraps, and install ring to secure.
Hook other end of strip to spring. Assure that trim
wheel is in neutral pOSition; indicator strip should
indicate neutral.
L Check rigging and adjustment per paragraph on
Rigging
and Adjustment of Elevator T rim Controls.
m. Be sure turnbuckle safety clips and cable and
cable guards are properly installed; then replace all
parts removed for access.
REMOVAL AND INST ALL AT ION OF ELEVATOR
TRIM JACKSCREW COMPONENTS
a. Remove aft baggage curtain from airplane.
b. Relieve tension on elevator trim cables by
loosening turnbuckles located in tailcone. (Apply
tape to cable on trim wheel).
c. Remove jackscrew access plates located on
bottom of stabilizer.
d. Disconnect chain from cable by removing
master link and pull chain from around sprocket.
e. Remove stop guard bracket by removing re-
taining bolts.
f. Drive out roll pin, then remove sprocket by
unscrewing.
g. Disconnect push rod from elevator and remove
elevator.
h. Remove internal components of jackscrew by
pulling push rod aft.
i. Clean parts thoroughly with cleaning solvent.
j. After parts have dried, install existing jaCk-
screws in existing elevator trim actuator housing
and operate jackscrews through their entire range of
travel.
k. If any roughness is noted, inspect jackscrews
for nicks or burrs.
1. If nicks or burrs are found on jaCkscrews, re-
move with crocus cloth or if necessary, replace
jackscrews.
m. Before reassembling elevator trim actuator
assemblies, lubricate jackscrew threads with molyb-
7-17
Copyright Commander Owners Group 2013 All Rights Reserved
**unofficial copy**