Rockwell Commander 112 - Flap Position Indicator; Fuel Quantity Indicators; Rudder Trim Position Gage; Stall Warning System

ROCKWELL
COMMANDER
112/B/TC/TCA
MAINTENANCE MANUAL
SECTION vm
ffiSTRUMENTS
FUEL QUANTITY INDICATORS
The fuel quantity indicators are used in conjunction
with a float-operated variable- resistance transmitter
in each fuel tank. The full tank position of the trans-
mitter float produces a minimum resistance through
the transmitter, permitting maximum current flow
through quantity indicator and maximum pOinter de-
flection. The fuel quantity indicators, located in the
sub-panel, are marked in quarter increments from
empty through full (Figure 8-5).
FLAP POSITION INDICATOR
Wing flap position is electrically indicated by a gage
mounted directly to the right of the flap switch. Posi.-
tion indications are transmitted by a sending unit
which is actuated by the flap motor jackscrew in the
fuselage.
RUDDER TRIM POSrnON GAGE
Rudder trim position is mechanically indicated on a
dual
reading gage installed directly to the right of the
oil temperature indicator in the instrument cluster
unit. The gage indicates both the trim position of the
rudder and nose wheel. This gage is connected by a
cable assembly to the rudder trim control assembly.
Rudder trim indication left or right is proportionately
to the movement of the rudder trim control assembly.
STALL WARNING SYSTEM
A stall warning lift detector switch is located in the
leading edge of the left wing at Station 80.77. The
lift detector switch is slightly spring-loaded to the
open position and is closed while approaching aircraft
stall speed when the air flow stagnation point moves
forward enough to cause a positive pressure on the
aft side of the vane, moving it forward. The lift de-
tector switch is set to close the circuit and sound the
stall warning horn at 5 to 10 knots above air craft stall
speed. The horn is located on the firewall in the cabin
area. External mounting screws located on each side
of the switch cutout, enables the lift detector switch
Change 1
to be adjusted. Loosening the lift detector switch
mounting screws allow s slight fore and aft movement
of the lift detector. MOving the lift detector forward
extends the stall speed indication away from stall
speed. Moving the lift detector slightly aft moves the
switch setting nearer the stall speed of the aircraft.
Operationally check stall warning system during flight
to assure warning horn sounds at 5 to 10 knots above
aircraft stall speed. The stall warning circuit is
supplied electrical power through a 5-amp circuit
breaker on the sub-panel.
NOTE
Lift detector switch replacement is
similar to the following steps; however,
battery cables must be disconnected
before removing detector switch.
a. Trace a light pencil mark on switch, along
edge of cutout in detector switch mounting plate.
This mark will be used to align detector switch dur-
ing reinstallation.
b. Remove screws securing detector and switch
plate, and Withdraw detector switch from wing.
c. Disconnect wiring and slip defective detector
switch out.
d. Install new detector switch and switch plate,
assuring pencil marks on switch align with cutout in
switch plate.
e. Operationally check stall warning system in
flight to assure warning horn sounds at 5 to 10 knots
above actual stall speed. Adjust lift detector switch
if system fails to operate properly (this step applies
to Model 112 aircraft with Serial Numbers 188 through
334, 336 through 371 and 373 through 380).
f. A ground check may be accomplished on Model
112
Serial numbers 335, 372, 381 and subsequent
and Models 112B/TC/TCA.
1 . Place master battery switch ON .
2. Move stall circuit test switch from
normal to test pOsition (test switch is located
in left wheel well).
3. Hold test switch in test position and gently
move lift detector switch forward and up. This
completes electrical circuit and stall warning
horn will sound.
8-14A/8-14B
Copyright Commander Owners Group 2013 All Rights Reserved
**unofficial copy**