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Pilot's Handbook of Aeronautical Knowledge
Aircraft Systems
Refueling Procedures

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Pilot's Handbook of Aeronautical Knowledge



Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making




The current method identifies AVGAS for aircraft with
reciprocating engines by the octane and performance number,
along with the abbreviation AVGAS. These aircraft use
AVGAS 80, 100, and 100LL. Although AVGAS 100LL
performs the same as grade 100, the "LL" indicates it has
a low lead content. Fuel for aircraft with turbine engines is
classified as JET A, JET A-1, and JET B. Jet fuel is basically
kerosene and has a distinctive kerosene smell. Since use of
the correct fuel is critical, dyes are added to help identify the
type and grade of fuel. [Figure 6-32]

Aviation fuel color-coding system.
Figure 6-32. Aviation fuel color-coding system.

In addition to the color of the fuel itself, the color-coding
system extends to decals and various airport fuel handling
equipment. For example, all AVGAS is identified by name,
using white letters on a red background. In contrast, turbine
fuels are identified by white letters on a black background.

Fuel Contamination
Accidents attributed to powerplant failure from fuel
contamination have often been traced to:
• Inadequate preflight inspection by the pilot.
• Servicing aircraft with improperly filtered fuel from
small tanks or drums.
• Storing aircraft with partially filled fuel tanks.
• Lack of proper maintenance.

Fuel should be drained from the fuel strainer quick drain and
from each fuel tank sump into a transparent container, and
then checked for dirt and water. When the fuel strainer is
being drained, water in the tank may not appear until all the
fuel has been drained from the lines leading to the tank. This
indicates that water remains in the tank, and is not forcing the
fuel out of the fuel lines leading to the fuel strainer. Therefore,
drain enough fuel from the fuel strainer to be certain that fuel
is being drained from the tank. The amount will depend on
the length of fuel line from the tank to the drain. If water or
other contaminants are found in the .rest sample, drain further
samples until no trace appears.

Water may also remain in the fuel tanks after the drainage
from the fuel strainer has ceased to show any trace of water.
This residual water can be removed only by draining the fuel
tank sump drains.

Water is the principal fuel contaminant. Suspended water
droplets in the fuel can be identified by a cloudy appearance
of the fuel, or by the clear separation of water from the colored
fuel, which occurs after the water has settled to the bottom
of the tank. As a safety measure, the fuel sumps should be
drained before every flight during the preflight inspection.
Fuel tanks should be filled after each flight or after the last
flight of the day to prevent moisture condensation within the
tank. To prevent fuel contamination, avoid refueling from
cans and drums.

In remote areas or in emergency situations, there may be no
alternative to refueling from sources with inadequate anticontamination systems. While a chamois skin and funnel
may be the only possible means of filtering fuel, using
them is hazardous. Remember, the use of a chamois will
not always ensure decontaminated fuel. Worn-out chamois
will not filter water; neither will a new, clean chamois that
is already water-wet or damp. Most imitation chamois skins
will not filter water.

Refueling Procedures

Static electricity is formed by the friction of air passing over the
surfaces of an aircraft in flight and by the .ow of fuel through
the hose and nozzle during refueling. Nylon, Dacron, or wool
clothing is especially prone to accumulate and discharge static
electricity from the person to the funnel or nozzle. To guard
against the possibility of static electricity igniting fuel fumes,
a ground wire should be attached to the aircraft before the fuel
cap is removed from the tank. Because both the aircraft and
refueler have different static charges, bonding both components
to each other is critical. By bonding both components to each
other, the static differential charge is equalized. The refueling
nozzle should be bonded to the aircraft before refueling begins
and should remain bonded throughout the refueling process.
When a fuel truck is used, it should be grounded prior to the
fuel nozzle contacting the aircraft.

If fueling from drums or cans is necessary, proper bonding
and grounding connections are important. Drums should be
placed near grounding posts and the following sequence of
connections observed:
1. Drum to ground
2. Ground to aircraft
3. Bond drum to aircraft or nozzle to aircraft before the
fuel cap is removed
When disconnecting, reverse the order.

The passage of fuel through a chamois increases the charge
of static electricity and the danger of sparks. The aircraft
must be properly grounded and the nozzle, chamois filter,
and funnel bonded to the aircraft. If a can is used, it should
be connected to either the grounding post or the funnel.
Under no circumstances should a plastic bucket or similar
nonconductive container be used in this operation.