UFC 3-460-03
21 JANUARY 2003
for routine operation or 203 millimeters (8 inches) per hour if more detailed information is
required for system troubleshooting.
6.5.7.4. Operator Controls. Controls are mounted on the PCP door panel. There is a three-
position selector switch that allows either Automatic, Off, or Flush mode operation. A second
selector switch allows selection of the lead pump; it has as many choices as there are pumps.
Selecting the lead pump also selects the sequence of pump operation. Selecting #1 as the lead
pump means Nos. 2, 3, and 4 will follow in sequence. By selecting #2 as the lead pump, Nos. 3, 4,
and 1 follow in sequence. Other controls include the Emergency Stop Button, and the Test, Reset,
and Acknowledge buttons of the annunciator panel.
6.5.7.5. Microprocessors. The microprocessor is the brain that actually turns things on and off.
By reading pressure, flow, and status, and relating these signals to the installed program, it
translates signals into action. There are two microprocessors in the PCP. They receive power
from separate but identical power conditioners and battery systems. They operate redundantly and
cycle off and on without interruption. Only one microprocessor actively controls the system at a
time, but the backup is continuously updated with system data. Should the active microprocessor
fail, the system automatically shifts to the backup without affecting system operation. Control can
also be shifted manually with a lockout key system. The operating program is stored in a battery-
backed memory, and is fully capable of cold starts without operator (POL personnel) intervention.
Program cold-start values are permanently installed in the memory, but are adjustable. By using
two thumbwheel switches, two push-buttons, and a twenty-character alphanumeric display, small
changes can be made. Various types of microprocessors are installed in the field. Refer to the
manufacturer's manual for specific details.
6.6. Sequence of Operations.
6.6.1. System in Automatic Mode. The Type III system is intended to stay continuously pressurized
at 75 psi while in the automatic idle mode, or between 100 and 130 psi during refueling operations.
6.6.1.1. Idle Condition. The system is in the idle condition when the system is in automatic mode
and no system pumps are running. Periodically, while in automatic mode/idle condition, the
system pressure may drop below 60 psi even though no aircraft refueling is being conducted.
When PIT 1 or PIT 2 (depending on microprocessor selection) senses that system pressure is
below 60 psi, the control system will cause the following:
6.6.1.1.1. The lead fueling pump will start.
6.6.1.1.2. The BPCV 58AF-9 solenoid will energize to enable (E/E) the valve to modulate open
at its set point (typically between 100 and 130 psi at the furthest hydrant outlet).
6.6.1.1.3. The PCV 58AF-3 solenoid will energize to close (E/C) the valve any time a pump is
running.
6.6.1.1.4. The D/FV 58AF-9-1 solenoid A (defueling) will de-energize to close (D/C) the valve,
and solenoid B (flush) will D/C any time the system is not in the flush mode.
6.6.1.1.5. The lead fueling pump immediately establishes a flow of 2271 liters per minute
(600 gallons per minute) that is sensed by the issue venturi DPT.
6.6.1.1.6. When no fuel is being delivered to an aircraft, the fuel will flow back to the
immediate operating storage tank through the return venturi. With one pump running, when the
67
Previous Page
