21 JANUARY 2003
HYDRANT FUELING SYSTEM, TYPE I (PANERO)
4.1. General Information. Prior to the development of hydrant fueling systems, aircraft were refueled
from drums of aviation fuel that were hauled to the aircraft. Later, fuel was transferred from storage
tanks into trucks that could pump the fuel into the aircraft. These methods were adequate for over-the-
wing filling of relatively small aircraft, but they proved too inefficient and time consuming for the larger
aircraft being built.
4.2. Original Panero. This was the first hydrant system used by the Air Force and it was built
throughout the 1940s and 1950s. These systems were based on the concept of bringing the aircraft to
the fuel. Fuel was pumped to a single refueling outlet at the edge of the aircraft parking ramp and
aircraft had to be moved to the fueling outlet, refueled, and then moved back to the parking location.
This reduced the need for truck refueling. The Original Panero system had two automatic control valves
in the filter meter pit: one on the refueling line and a separate valve on the defueling line. Since hydrant
systems are constantly improved and upgraded there are few Original Panero systems left. Major
modifications to the Original Panero created the Modified Panero system. The Modified Panero system
is still in use at some military installations today and uses one automatic control valve (302AF
refuel/defuel control valve) in the filter meter pit to perform both refuel and defuel operations. This
chapter includes a description of the Modified Panero's operation, major components, and pressure
settings (see Figure 4.1).