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CARGO HANDLING SYSTEM -OPERATION -CONTROLS
The yellow Bay on LEDs come on to let you know which bays have active PDUs.
The BAY OFF switches are three-position toggle switches spring-loaded to the center position. The up or down position lets you set the PDUs on or off. (Up or down for on, up or down again for off.) The P27 aft cargo handling control panel (not shown) has these bay off switches:
* A, B, C, and G.
Lighting for the cargo handling control panel comes from an area light above the panel. The light shines down on the panel so you can see it when it is dark outside. The light also shows that power is available to the cargo handling system, because it is on when the ground handling bus has power.
The cargo control joystick is not part of the cargo handling control panel.
Cargo Control Joystick
The forward and aft (not shown) cargo control joysticks let you control the longitudinal and lateral movement of ULDs. The joystick has five positions: IN, OUT, FWD, AFT and neutral. It is spring loaded to the neutral position.
Secondary Joystick Panel
This panel has only the secondary joystick. This joystick is a three-position toggle switch that is spring-loaded to the middle position. The switch functions as a joystick because it lets you move cargo forward or aft but not on to the ball panel.
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CARGO HANDLING SYSTEM -OPERATION -CONTROLS
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CARGO HANDLING SYSTEM -FUNCTIONAL DESCRIPTION -POWER
General
The cargo handling system gets power from the ground handling bus. It uses three phase 115v ac for operation and 28v dc for control.
Operation power loads go to two circuits: left system power and right system power. The CSC uses the left and right system relays to control system power.
System Power
The ground handling bus gives power directly to the cargo control panel area light. The light is on when the bus has power.
The CSC turns on system power if you open the cargo door to full open and set the cargo handling system power switch to the ON position. When power is on the system, the CSC turns on the system power ON LED.
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CARGO HANDLING SYSTEM -FUNCTIONAL DESCRIPTION -LATERAL GUIDE
General
For control, the lateral guides have two major groups, forward and aft. Each major group has two minor groups, left and right. Guides in each major group have a number. The numbers increase from right to left.
These are the minor groups and the guides in them:
*
Forward right: FWD 1 and FWD 2
*
Forward left: FWD 2 and FWD 3
*
Aft right: AFT 1 and AFT 2
*
Aft left: AFT 3 and AFT 4.
Only the guides in a single major group operate at a time. Within a major group, the left and right minor groups of guides may operate independently or at the same time. The lateral guides have two positions, up and down.
The CSC uses inputs from these switches to set the position of the lateral guides:
*
Cargo control joystick
*
PDU forward/aft switch
*
PDU left/both/right switch
*
Pallet/container switch.
CSC Control
Power switching circuits in the CSC, get 115v ac single phase voltage from the ground handling bus. The switching circuits control the voltage and monitor for current flow to the lateral guides. The default value for CSC logic is to command (CMD) the guides to up. The down CMD is based on switch inputs.
The power switching circuits give voltage to move the guides up or down. Limit switches in the guides stop the current flow and apply a brake when the guide moves to the desired position. If a guide does not stop the current within three seconds after a up or down CMD is given, the power switching circuit removes the voltage. If no current draw is sensed within seventy-five milliseconds after a CMD is given, the voltage is removed.
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