Figure 5-9.Air or nitrogen servicing trailer.
Always know the pressure existing in the system
to be filled and the pressures in all the cylinders to be
used up in the cascading process before beginning a
A malfunctioning pressure regulator should be
disconnected from the line, closing its associated
shutoff valve. The trailer can then be operated with the
The charging hose must never be stretched to
reach a connection. Position the trailer so the hose is not
under tension while servicing an aircraft.
After servicing an aircraft system, stow the
servicing hose in its container to ensure that it is not
damaged by dragging along behind the trailer.
The preoiler (PON-6) is a portable, hand-carried,
hand pump with a 3-gallon capacity. Figure 5-10
shows the major components of the PON-6. It will
deliver oil at a pressure up to 100 psi. A sight glass
(not shown in fig. 5-10) is located on the side of the
reservoir and shows the level of the oil. An oil pressure
gauge indicates oil line pressure. An oil meter records
the amount of oil delivered. The meter is calibrated in
ounces (outer scale) and quarts (inner scale). A
push-button bleed valve relieves pressure on the meter
and service hose and bleeds oil back to the reservoir.
The service hose is 6 feet long. A complete drain bottle
assembly is provided for overflow oil from the aircraft