Fuel Systems

Question 1

two types of aviation fuel

Answer 1

AVGAS - Aviation Gasoline

Turbine Fuels - Jet fuel

Question 2

what were the four available grades of AVGAS

Answer 2

RED - 80/87
BLUE - 91/96
GREEN - 100/130
PURPLE - 114/145

Question 3

the new and most commonly available types of AVGAS are

Answer 3

RED - 80
GREEN - 100
BLUE - 100LL (Low Lead)

Question 4

what are the three types of jet fuel? how are they identified?

Answer 4

Jet A - black box with black outline
Jet A1 - Black box with gray outline
Jet B - black box with bright yellow outline

Question 5

what are the main ways fuel can be identified

Answer 5

AVGAS is died to match its grade ( red = 80)

Jet fuel jrucks and hoses are marked with a coloured band (black/gray/yellow) because the fuel is all the same colour

Question 6

what does the numerical value in AVGAS represent?

Answer 6

The octane rating or the fuels willingness to burn.

Question 7

what is the difference between Jet A and Jet A1

Answer 7

different freezing points. Jet A freezes at -40 whereas Jet A1 freezes at -47

Question 8

octane

Answer 8

willingness to burn. higher octane rating means a higher resistance to detonation

Question 9

vapor lock

Answer 9

when fuel vaporizes in the lines causing a blockage of fuel flow. can starve engine of fuel leading to stoppage

Question 10

what are the different types of contaminations

Answer 10

water - build up of moisture located within the fuel tank

Water slug - large volume of water trapped in fuel lines. blocks fuel flow

micro organisms - forms a black or brown sludge within fuel tank

Question 11

what is the most common use for Jet B fuel? what makes it so undesirable

Answer 11

Helicopters and military aircrafts

Jet B is a combination of Kerosene based Jet A (which is mostly stable but reacts to static electricity) and AVGAS (which is very volatile and produces high amounts of static electricity).

Question 12

what is defueling

Answer 12

when an aircrafts fuel system is completely flushed out. usually due to a contamination

Question 13

what are the different types of fuel pumps

Answer 13

mechanically driven
piston type - high pressure
diaphragm type - low pressure

Question 14

different types of fuel valves

Answer 14

hand operated
motor operated
solenoid operated

Question 15

if there is a breach the left wing fuel tank that causes a starvation to the left side turbine, what system is in place to allow that turbine to keep receiving fuel?

Answer 15

Crossfeed. funnels fuel from full tank directly into effected engine to allow for propper operation while preventing any further fuel loss

Question 16

Volatility

Answer 16

measure of a fuels ability to change from liquid to a vapor

Question 17

Viscosity

Answer 17

measures a fuels resistance to flow. fuels with higher viscosity retain contaminants.

Question 18

entrained water

Answer 18

water that has become suspended within the fuel. only happens to more viscus fuels

Question 19

what causes fuel fitler clogging? how can it be prevented?

Answer 19

Water slugs and entrained water that freezes in the fuel system causing ice crystals to build.

use a hydraulic heat exchanger to preheat the fuel and break up ice crystals

Question 20

Surfactants

Answer 20

Surface Active Agents - Soapy detergents that form naturally in fuel. appears as a tan to dark brown liquid

Question 21

When dealing with Volatile fuels such as AVGAS and Jet B, what is a good safety precaution to follow?

Answer 21

always bond fuel to the truck and ground both vehicles to earth

Question 22

what class of fire extinguisher is best for fighting fuel fires

Answer 22

Class B - Combustible liquids

Question 23

what would be the most common reasons to defuel an aircraft?

Answer 23

Contamination in the fuel system or to allow maintenance work to be done on the fuel tanks. contaminated fuel is disposed of whereas all other fuel can be stored in a truck to be reused once maintenance is finished.

Question 24

what common practices are used to deter misfueling

Answer 24

all fuels (Jet or AVGAS) are colour coded and trucks and nozzles are coded to match.

nozzles are also different shapes and sizes to not allow them to fit into an aircraft with an incorrect fuel type.

Question 25

AVGAS can be used in a turbine engine with minimal consequences however jet fuel can not be used in a turbine engine. why not?

Answer 25

AVGAS is very volatile and therefor reacts to sparking caused by spark plugs within the engine. it can also be ignited through extreme heat/pressure which allows it to function without issue in a turbine engine. however, because Jet fuel is Kerosene based and very stable, it will not light when met with a spark and will subsequently cause a turbine engine to seize.