maintenance instruction manual (MIM) contains
illustrations of and instructions for the pressure fueling
The pressure nozzle shown in figure 5-5 is
permanently attached to the fuel hose. The pressure
nozzle has a ground wire, which is used to drain off
any static electricity that has built up in the nozzle.
Once the nozzle is attached to the aircraft, however, it
acts as a ground.
When the pressure nozzle is connected to the
aircraft, it opens a spring-loaded valve within the inlet
to the fuel tanks. Aircraft that use this system have
automatic equipment for shutting off the fuel flow
when the tanks are full.
Because the controls differ from one aircraft to
another, you should always check the applicable MIM
before pressure fueling an aircraft. The general
procedures for pressure fueling are as follows:
Remove the pressure-fueling receptacle safety
cap by turning it counterclockwise. Pull the
pressure-fueling nozzle dust cover up and to one side of
the outer shell.
Ground the nozzle by inserting the grounding
plug into its receptacle on the aircraft.
3. Visually inspect aircraft adapter for any
damage or significant wear. (A worn or broken adapter
will allow the poppet valve to open and spray or spill
4. Lift the nozzle by its handles into position.
Engage the lower slot over the lower lug on the fueling
receptacle. Tip the nozzle so that the upper slots engage
the upper lugs. Press the nozzle in firmly so that all three
nozzle lock keys are depressed. Lock the nozzle by
rotating the lifting handles clockwise.
Set the refueling panel switches in the proper
position, and apply electrical power to the aircraft.
6. Position the vent monitors, as necessary,
according to the applicable MIM.
NOTE: The vent monitors are assigned to the
various fuel system vents to ensure that the aircrafts
fuel cells are venting properly. If the cells are not
vented properly, there is the possibility that the cell
will rupture and cause major structural damage.
7. When the nozzle is locked in place, the opening
handle is free to turn when fueling is started. Turn the
handle to the FULL OPEN position to start fueling.
Rotating the opening handle more than 180° opens the
poppet valve in the nozzle and locks it in the OPEN
position. Position the appropriate switch on the fuel
panel to the FUEL position. The fuel should shut off
automatically when the ceils are full.
During pressure fueling, the fuel system
should be inspected carefully for leakage. If
any leaks are apparent, fueling should be
stopped and corrective action taken. A fuel
leak may cause injury or death to personnel.
8. When the fueling operation is complete, remove
the pressure nozzle by rotating the lifting handles
counterclockwise until the nozzle is unlocked from the
fueling receptacle. Pull the dust cover up over the nozzle
face immediately. Then replace the safety cap on the
You must take every safety precaution to make
sure that no dirt or foreign matter enters the nozzle.
The nozzle nose should be completely clean before it
is connected to the aircraft. The dust cover must
always be kept on the nozzle except when actually
fueling an aircraft.
The pressure fueling nozzle can be damaged by
careless handling. Do not drop the nozzle or allow it
to swing heavily against structures or equipment
during handling. Never drag the nozzle on the
The operating action of the nozzle should never be
forced. If the unit does not couple freely or open or
close readily, locate and correct the misalignment or
Defueling may be necessary for many reasons,
some of which are fuel cell repairs, removal of external
fuel tanks, failure of fuel system components, and
changing fuel loads. Aircraft that use pressure fueling
are normally defueled from the pressure fueling
adapter. This allows the entire system to be defueled
from a single point. Some older aircraft have one or
more defueling valves. Some residual fuel will often
be left in the bottom of the fuel cell following
defueling. Usually, residual fuel can be emptied or
drained through the fuel cell water drain valves. A
special adapter and appropriate container are used to
catch the fuel. When external fuel tanks are defueled,