UFC 3-460-03
21 JANUARY 2003
Chapter 5
HYDRANT FUELING SYSTEM, TYPE II (PRITCHARD)
5.1. General Information. The Type II Pritchard System was developed in 1955 to improve operating
characteristics in conventional hydrant fueling systems. It can service multiple hydrant outlets per
control pit, so allowing more flexibility in parking aircraft and reducing the need to tow aircraft to
refueling positions. The Type II pumphouse is similar to the Type I except the separate defuel tank is no
longer needed. Instead, one Type II operating tank is designated as the defuel tank for the day. The
filter/meter pit of the Panero system is now the lateral control pit (LCP), and a defueling pump with four
different automatic valves has replaced the dual-purpose 302AF valve. The MH-2 hose cart is standard
equipment for connecting the hydrant outlet to the aircraft, so there is no need for filtration or meters in
the LCP. Figure 5.1 shows the layout of a typical system. The following is a simplified description of
operation:
5.1.1. Refueling. Like the Type I system, when fuel is required at a hydrant outlet, the operator
places a magnet on the refueling magnetic control assembly (KISS switch). This causes a preselected
pump in the pumphouse to start and energizes the solenoid on the refueling control valve (90AF-8) in
the hydrant lateral control pit. Fuel moves from the pumphouse into the fueling manifold and to the
LCP. It enters the refueling control valve and causes it to open. The 90AF-8 valve provides five
functions: pressure reduction; nonsurge; pressure relief; excess flow shutoff; and emergency shutoff.
Fuel flows through the hydrant adapter and the MH-2 hose cart to the aircraft. During refueling, the
relief valve relieves excess pressure from the upstream side of the 90AF-8 into the defuel line.
39
Previous Page
