MIL-HDBK-1022A
piping senses flow rate in the loop and works in conjunction
with a venturi in the return loop. Depending on the flow
demand, the return venturi turns on/off additional pumps as
required. If return flow is below a preset limit (indicating
that fuel is being dispensed), a low flow is sensed and
additional pump(s) are turned on, one at a time, until a
steady flow condition is reached. Conversely, if the return
flow is above a preset limit (indicating less fuel is being
dispensed), the return venturi senses high flow conditions and
turns the pump(s) off, one at a time, until the system is
brought to rest. The continued circulation of the fuel not
only provides a self-cleaning action but when properly
adjusted, the system is able to more closely match the varying
fuel filling rates of aircraft. This provides smooth
operation and eliminates surge pressure spikes that have been
so destructive to aircraft fueling systems of the past. In
order to ensure the highest quality of fuel, contact with bare
carbon steel is limited to an absolute minimum prior to
filtration and is not permitted downstream of the issue
filter/separators, unless specifically authorized by Service
Headquarters.
4.4.2.1
General Requirements. Install aircraft direct
fueling systems only when specifically authorized by Service
Headquarters. Service Headquarters or Air Force MAJCOMs
assist in determining the number and type of stations required
by the activity and with locating hydrant pits in aircraft
parking ramps. Construct new facilities only for issuing
aviation turbine fuels through pressurized single point and
closed circuit fueling nozzles. Locate fueling stations at
the edge of the aircraft parking apron or taxiways or at apron
parking spots for large frame aircraft. Size and configure
these systems based on the types of aircraft to be refueled,
aircraft fuel capacity, and the number and types of aircraft
to be simultaneously refueled. It is important to ensure a
firm aircraft parking plan has been established before
proceeding with the hydrant pit layout design. Some aircraft,
such as fighters and some helicopters, may be refueled with
engines or support equipment running. See Facility Plate Nos.
008 through 010. For additional guidance on Air Force
projects, refer to AFH 32-1084.
4.4.2.2
Fixed-Wing Small-Frame Aircraft. Locate aircraft
direct fueling stations for small-frame aircraft (carrier
aircraft, patrol aircraft, fighter aircraft, and small
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