Specifications

SECTION II
AIRPLANE AND SYSTEMS
MODEL 560
During descent, the pilot can view the selected landing field altitude by pressing the FL button on the
controller. The display will show cabin altitude, allowing the pilot to set the desired cabin altitude prior to
landing. The controller then controls the cabin pressure rate of change to maintain the displayed cabin
altitude.
In this position, electric power is removed from the controller (and subsequently the climb and dive
solenoids associated with the primary outflow valve). All changes to the outflow valves are now
commanded using differential pressure from cabin and ambient sources. Placing the MANUAL valve in the
UP position will increase cabin altitude, and placing the valve in the DOWN position will decrease cabin
altitude.
The amount of cabin altitude change and the cabin altitude rate of change is controlled by the amount
of time the MANUAL valve is held in the UP or DOWN position. Because the manual valve uses cabin
pressure to open and close the outflow valves, reaction time will increase at low cabin Delta-P. Safety
features in the manual toggle valve will not allow rate selections beyond Delta-P limits.
EMERGENCY DUMP
The EMER DUMP ON switch is stowed in the de-activation position. The EMER DUMP ON switch
may be used for rapid equalization of the cabin and ambient pressures up to approximately 13,000 feet.
When activated, the primary outflow valve climb solenoid is electrically commanded to vent air out of the
control chambers, causing the primary and secondary outflow valves to open and dump cabin pressure.
The PRESS SOURCE selector must be OFF to obtain complete depressurization at altitudes above 13,000
feet. However, limiters in the solenoid will not allow cabin altitude to exceed 14,500 feet regardless of
commands from the EMER DUMP ON switch.
BUILT IN TEST FUNCTIONS
The controller incorporates two sets of built-in diagnostics tests. The first test is an internal check of
the controller and is performed continuously during operation. If an internal fault is detected, power is
removed form the primary outflow valve climb and dive solenoids. The RATE and SET ALT displays will go
blank, providing the pilot with immediate indication of the controller failure. The system is now in the
manual mode of operation, with the outflow valves remaining in the last commanded position. If this failure
occurs in flight, the cabin pressure altitude may then be controlled using the MANUAL toggle valve.
If the controller detects a loss of the air data computer signal, a yellow warning indicator will illuminate
and the controller will automatically switch to the Isobaric Mode of operation. The controller will continue to
operate in Isobaric Mode until the signal is restored. If the signal is restored in flight, the controller will
switch back to the auto schedule mode of operation.
While on the ground, the integrity of the system may be checked by pressing and holding the EXER
button for approximately 2 minutes. The controller will command the outflow valves to the closed position
and pressurize the cabin to 200 feet below current field elevation. Upon release of the button, the controller
will perform a display test and gradually re-open the outflow valves to their full open position, depressurizing
the cabin.
NOTE
In flight, the EXER button provides only a lamp test.
EMERGENCY PRESSURIZATION
In the EMER position, the emergency pressurization valve opens allowing hot bleed air from the left
engine to enter the cabin directly and the EMER PRESS annunciator light will illuminate. The air cycle
machine is bypassed with emergency pressurization selected, cabin temperature will rise, and AUTOMATIC
or MANUAL temperature control will be disabled. Cabin temperature can be controlled to some extent with
the left throttle. Retarding the left throttle will lower bleed air temperature, but excessive reduction will allow
the cabin altitude to climb.
Emergency pressurization will also automatically activate at 14,500 foot cabin altitude regardless of the
bleed air control valve switch position, and will deactivate by 12,000 foot (descending).
I 2-52 Configuration AA 56OMB-01