2-37. CONTROL WHEELS
Elevator and aileron control surfaces are oper-
ated by manually actuating either the pilots or copi-
lots control wheel. Switches are installed in the out-
board grip of each wheel to operate the elevator trim
tabs. A microphone switch, a chaff dispense switch,
and an autopilot/yaw damp/electric trim disconnect
switch are also installed in the outboard grip of each
wheel. A transponder ident switch is installed on top
of the inboard grip of each control wheel. These con-
trol wheels (fig. 2-17) are installed - on each side of
the instrument subpanel. A manually wound 8-day
clock is installed in the center of the pilots control
wheel, and a digital electric clock is installed in the
center of the copilots control wheel. A map light
switch, and a pitch synchronization and control
wheel steering switch are mounted adjacent to the
clock in each control wheel.
2-38. RUDDER SYSTEM.
Rudder Pedals. Aircraft rudder control and
nose wheel steering is accomplished by actuation of
the rudder pedals from either pilots or copilots sta-
tion (fig. 2-8). The rudder pedals may be individu-
ally adjusted in either a forward or aft position to
provide adequate leg room for the pilot and copilot.
Adjustment is accomplished by depressing the lever
alongside the rudder pedal arm and moving the
pedal forward or aft until the locking pin engages in
the selected position.
Yaw Damp System. A yaw damp system is
provided to aid the pilot in maintaining directional
stability and increase ride comfort. The system may
be used at any altitude and is required for flight
above 17,000 feet. It must be deactivated for takeoff
and landing. The yaw damp system is a part of the
autopilot. Operating instructions for this system are
contained in Chapter 3. The system is controlled by
a YAW DAMP switch adjacent to the ELEV TRIM
switch on the pedestal extension.
Rudder Boost System. A rudder boost sys-
tem is provided to aid the pilot in maintaining
directional control resulting from an engine failure
or a large variation of power between the engines.
Incorporated in the rudder cable system are two
pneumatic rudder boosting servos which actuate the
cables to provide rudder pressure to help compen-
sate for asymmetrical thrust.
(1.) During operation, a differential pres-
sure valve accepts bleed air pressure from each
engine. When the pressure varies between the bleed
air systems, the shuttle in the differential pressure
valve moves toward the low pressure side. As the
pressure difference reaches a preset tolerance, a
switch closes on the low pressure side which acti-
vates the rudder boost system. This system is
designed only to help compensate for asymmetrical
thrust. Appropriate trimming is to be accomplished
by the pilot. Moving either or both of the bleed air
valve switches on the overhead control panel to
PNEU & ENVIRO - OFF position will disengage the
rudder boost system.
Condition levers must be in LOW IDLE
position to perform rudder boost check.
The system is controlled by a switch
located on the extended pedestal placarded RUD-
DER BOOST (on) - OFF (fig. 2-7), and is to be
turned on before flight. A preflight check of the sys-
tem can be performed during the run-up by retard-
ing the power on one engine to idle and advancing
power on the opposite engine until the power differ-
ence between the engines is great enough to activate
the switch to turn on the rudder boost system.
Movement of the appropriate rudder pedal (left
engine idling, right rudder pedal moves forward) will
be noted when the switch closes, indicating the sys-
tem is functioning properly for low engine power on
that side. Repeat the check with opposite power set-
tings to check for movement of the opposite rudder
pedal. The system is protected by a 5-ampere circuit
breaker placarded RUDDER BOOST, located on
the overhead circuit breaker panel (fig. 2-26).
With brake deice on, rudder boost may be
2-39. FLIGHT CONTROLS LOCK.
Remove control locks before towing the
aircraft or starting engines. Serious dam-
age could result in the steering linkage if
towed by a tug with the rudder lock
Positive locking of the rudder, elevator and aile-
ron control surfaces, and engine controls (power
levers, propeller levers, and condition levers) is pro-
vided by a removable lock assembly (fig. 2-18) con-
sisting of two pins, and an elongated U-shaped strap
interconnected by a chain. Installation of the control
locks is accomplished by inserting the U-shaped
strap around the aligned control levers from the