1. Aircraft Fuel Systems

2. Avgas
• Aviation fuel is a specialized type
of petroleum-based fuel used to
power aircraft.
• Generally of a higher quality than fuels used in
less critical applications such as heating or
road transport, and often contains additives to
reduce the risk of icing or explosion due to
high temperatures, amongst other properties.

4. Avgas
• Avgas (aviation gasoline) is an aviation fuel used
to power piston-engine aircraft.
• It can be distinguished from mogas (motor
gasoline), which is the everyday petroleum
spirit used in cars.
• Avgas is formulated for stability, safety, and
predictable performance under a wide range of
environments.
• Avgas is typically used in aircraft that
use reciprocating or wankel engines.
• Dyes for the fuel are required in some countries.

5. Avgas
• Aviation fuels consist of blends of over a
thousand chemicals:
– primarily Hydrocarbons (paraffins, olefins, naphth
enes, and aromatics) as well as additives such
as antioxidants and metal deactivators, and
impurities.
– Principal components include n-octane, isooctane.
– Like other fuels, blends of Aviation fuel used in
piston engine aircraft are often described by
their Octane rating.

6. 100LL
• The most commonly used aviation fuel is dyed
blue for easy visual identification.
• 100LL, spoken as "100 low lead", contains a small
amount of tetra-ethyl lead (TEL),
a lead compound that reduces gasoline's
tendency to spontaneously explode (detonation
or "knock") under high loads, high temperatures
and high pressures.
• Sustained detonation causes catastrophic engine
failure.

7. Avgas
Table of Aviation Fuel Types
Country Fuel Lead content Status Dye
Phased out,
Worldwide 80/87 Low lead difficult to red
obtain
Not produced
Worldwide 82UL Unleaded purple
since 2008
Most commonly
Worldwide 100LL Low lead used aviation blue
fuel
4 grams of lead In process of
Worldwide 100/130 per US gallon being replaced green
(1.1 g/l) by 100LL
Discontinued
(sometimes
Worldwide 91/96 brown
produced for
races)
Discontinued
Worldwide 115/145 (mainly military purple
use)

9. Don’t Lie About Your Fuel State
• I’ve never overloaded my airplane
• I have the traffic in sight
• Yes, tower, I responded. You didn't hear me?
• You're not picking up my squawk code? Here,
let me recycle the transponder
• I have the check-list memorized
• I broke out of the clouds right at minimums

10. Still????
• http://www.google.com/search?um=1&hl=en
&safe=off&biw=1024&bih=707&q=the%20run
way%20behind%20you&ie=UTF-
8&sa=N&tab=iw#sclient=psy&hl=en&safe=off
&biw=1024&bih=707&source=hp&q=aircraft+
crash+ran+out+of+fuel&aq=f&aqi=&aql=&oq=
&pbx=1&bav=on.2,or.r_gc.r_pw.&fp=a316b5c
db3fe9040

11. Weight & Balance
• Avgas has a density of 6.02 lb/U.S. gal at
15 °C, or 0.721 kg/l, and this density is
commonly used for weight and
balance computation.
• Density increases to 6.40 lb/US gallon at -40
°C, and decreases by about 0.5% per 5 °C (9
°F) increase in temperature.
• As you use fuel, your CG will move.

12. ?Hybrid?

13. Very Important

14. What’s Going In?
• Be present when Fuel is pumped.
– Quantity
– Quality
– Correctness
– Damage to A/C

15. Cases
On March 2, 2008, a turbo-normalized Cirrus
SR22 was destroyed when it crashed shortly
after takeoff in Rio de Janeiro, Brazil, killing all
four people aboard. Shortly after the aircraft
departed from Runway 20, the airplane's engine
lost power, and the aircraft hit a building and
exploded. Further investigation revealed that
the aircraft had been refueled with Jet A instead
of 100LL.

16. Effects of Contamination
• Zero Octane
• Instant destructive detonation
• You will loose the engine

17. The Fuel System
• Tanks
• Lines
• Vents
• Drains
• Primer
• Gauges
• Fuel Pump & Gravity Feed

18. Fuel Pump System
• Usually found in Low Wing Aircraft
• High Performance aircraft with Fuel Injected
engines
• Usually will have a boost pump (Aux Pump)

19. Question
In all fuel injected aircraft, if the engine fuel
pump fails you will still be able to run the engine
if the aux fuel pump is activated?
False

20. Fuel Pressure
Fuel Pressure Gauge Fuel Pump
• Cherokee Six • Lycoming

21. The Relationship

22. Low Wing Design

23. High Wing Gravity Feed

24. Gravity Feed

25. Question
In order to maximize range performance, on
aircraft equipped with more than one fuel tank,
it is common and safe to run a tank completely
dry before switching fuel tanks.
Vapor Lock

26. Question
Once vapor lock is induced, there are steps a
pilot can take while flying to counter it.
False

27. Fuel Tank Venting/Overflow Drain

28. Fuel Gauges

29. The Digital Age

30. More Reasonable

31. Fuel Selector Valve

32. Fuel Cross Feed

33. Question
Using a fuel grade higher than specified can
cause cylinder head and engine temperatures to
exceed normal operating limits.
False

34. Question
You arrive at your aircraft for a flight and realize
you need fuel. The fuel should be drained and
checked immediately following the filling/adding
of fuel to the fuel tanks.
False

35. Fuel Tips
• Infrequently used fuel tanks should have their
sumps drained before filling
• Agitation action of fuel entering the tank may
suspend or entrain liquid water or other
contaminants.
• After fueling, wait at least 15 minutes per foot
of depth of the tank before sumping

36. AC-20-125
• How much fuel says the FAA?
– 10 ounces or more!!
• Cross feed and multiple tanks should be
checked separately.

37. 3 Useless Things in Aviation
The runway behind you
The sky above you
The Fuel in the truck