Specifications

SECTION II
AIRPLANE AND SYSTEMS
MODEL 560
A switch on the instrument panel allows the pilot to select antiskid ON or OFF. When the switch is in
the ON position, the antiskid function is operational. With the control switch in the OFF position, the
ANTISKID INOP light on the annunciator panel will illuminate and the pilot will have power braking available
without the antiskid function. If the power system should fail, braking will only be available through the
back-up pneumatic system. The antiskid control module incorporates test circuitry which continually
monitors the antiskid system. If a fault is detected, the ANTISKID INOP light will illuminate on the
annunciator panel. Certain faults in the system are displayed on a “BITE” indicator (fault display unit),
which is located under the removable panel at the aft of the left nose compartment. A white flag may
appear in any of the five circular indicators located in a row on the fault display unit. The faults which may
be displayed are: left transducer failure (LEFT XDCR), right transducer failure (RIGHT XDCR), left and right
squat switch disagreement (SQUAT DISAGREE), control valve failure (VALVE), and control unit failure
(CONTROL).
If hydraulic pressure in the power system drops below 750 PSI, the LO BRK PRESS light will
illuminate.
The brake system receives electrical power through a 20-ampere circuit breaker on the left circuit
breaker panel, which is labeled SKID CONTROL. The brake antiskid system and the power brake
motor/pump receive power through this circuit breaker which, when disengaged, disables the power brake
system. Braking is then available only by means of the pneumatic brake system.
PARKING BRAKE
The parking brake is a part of the normal brake system and employs controllable check valves that
can prevent the return of fluid after the brakes have been set. Parking brakes are set by depressing the toe
brakes and pulling out the black parking brake handle located under the lower left side of the instrument
panel. The parking brake should not be set if the brakes are very hot. This increases brake cool-down
time due to decreased airflow, and may result in sufficient heat transfer from the brakes to cause the
parking brake thermal relief valves to open or to melt the thermal relief plugs in the wheel, causing deflation
of the tire.
EMERGENCY BRAKING
In the event of normal hydraulic braking system failure, a pneumatic system is available. The
pneumatic pressure required is contained in the emergency air bottle and is controlled by a lever with red
knob located to the left of the AUX GEAR CONTROL T-handle. Pulling the lever aft will apply equal
pressure to both main landing gear brake assemblies. Releasing the back pressure on the lever and
allowing it to move forward will relieve the pressure. The air pressure to the brakes may be modulated to
provide any braking rate desired, but differential braking and antiskid will not be available. The emergency
air bottle, when fully charged, contains sufficient pressure for ten or more full brake applications. For the
most efficient use of the system, apply sufficient air pressure to the brakes to obtain the desired
deceleration rate. Maintain that pressure until airplane is stopped. When the handle is released, residual air
pressure from the brakes is exhausted overboard.
NOTE
Normal braking should not be applied while using the pneumatic brakes. Depressing the
pedals will reposition the shuttle valves in the brake lines to open, allowing high pressure
air from the brake housing to enter the brake hydraulic reservoir, which might possibly
rupture it.
Adequate emergency braking for most conditions will be available from a properly serviced air bottle,
even if the landing gear have been extended pneumatically. After stopping and clearing the runway, it is
probably best to shut down the engines and have the airplane towed to the ramp, as there is no warning in
the cockpit when the air bottle is depleted.
I 2-28 Configuration AA 56OMB-01