Beechcraft C-12C Operator And Technical Reference Manual page 83

2-46. RUDDER SYSTEM.
a. Rudder Pedals. Aircraft directional control
and nose wheel steering is accomplished by actuation
of the rudder pedals from either pilot's or copilot's
station, Figure 2-10.
individually adjusted in either a forward or aft position
to provide adequate legroom for the pilot and copilot.
Adjustment is accomplished by pressing the lever
alongside the rudder pedal arm and moving the pedal
forward or aft until the locking pin engages in the
selected position. Toe brake coverage, is provided in
Paragraph 2-9.
b. Yaw Damper.
provided to aid the pilot in maintaining direction
stability and increase ride comfort. The system may
be used at any altitude and is required for flight above
17,000 feet for aircraft without dual aft body strakes. It
must be deactivated for takeoff and landing and below
200 feet above terrain. The yaw damper 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 extended pedestal.
c. Rudder Boost. Rudder boost is provided to
aid the pilot in maintaining directional stability 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 that
actuate the cables to provide rudder pressure to help
compensate for asymmetrical thrust. Rudder boost is
not required for flight.
Rudder boost may be inoperative when
brake deice is on.
(1) During operation, a differential pressure
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 activates the rudder
boost system. This system is designed only to help
compensate for asymmetrical thrust.
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
C D T1 and the ENVIR & PNEU BLEED AIR
the off position will disengage the rudder boost
system.
The rudder pedals may be
A yaw damper system is
NOTE
Appropriate
Condition levers must be in LOW IDLE
position to perform rudder boost check.
(2) The system is controlled by a switch
located on the extended pedestal below the rudder
trim wheel, placarded RUDDER BOOST / OFF, and is
to be turned on before flight. A preflight check of the
system can be performed during the run up by
retarding the power on one engine to idle and
advancing power on the opposite engine until the
power difference 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
system is functioning properly for low engine power on
that side. Repeat the check with opposite power
settings to check for movement of the opposite rudder
pedal. The system is protected by a 5-ampere circuit
breaker on the overhead circuit breaker panel,
placarded RUDDER BOOST.
2-47. FLIGHT CONTROL LOCK.
Remove control locks before towing the
aircraft or starting engines.
damage could result in the steering linkage
if towed by a tug with the rudder lock
installed.
Positive locking of the rudder, elevator and
aileron control surfaces, and engine controls (power
levers, propeller levers and condition levers) is
provided by a removable lock assembly, Figure 2-23,
consisting of two pins and an elongated U-shaped
strap interconnected by a chain.
controls lock is accomplished by inserting the U-
shaped strap around the aligned control levers from
the copilot's side; then the aileron-elevator locking pin
is inserted through a guide hole in the pilot's control
column assembly, thus locking the control wheel. The
rudder is held in a neutral position by an L-shaped pin,
which is installed through a guide hole in the floor aft
of the pilot's rudder pedals. The rudder pedals must
be centered to align the hole in the rudder bellcrank
with the guide hole in the floor. Remove the locks in
reverse order, i.e., rudder pin, control column pin, and
power control clamp.
T2 to
TM 1-1510-218-10
NOTE
CAUTION
Serious
Installation of the
2-67