Fuel Systems Flashcards
two types of aviation fuel
AVGAS - Aviation Gasoline
Turbine Fuels - Jet fuel
what were the four available grades of AVGAS
RED - 80/87
BLUE - 91/96
GREEN - 100/130
PURPLE - 114/145
the new and most commonly available types of AVGAS are
RED - 80
GREEN - 100
BLUE - 100LL (Low Lead)
what are the three types of jet fuel? how are they identified?
Jet A - black box with black outline
Jet A1 - Black box with gray outline
Jet B - black box with bright yellow outline
what are the main ways fuel can be identified
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
what does the numerical value in AVGAS represent?
The octane rating or the fuels willingness to burn.
what is the difference between Jet A and Jet A1
different freezing points. Jet A freezes at -40 whereas Jet A1 freezes at -47
octane
willingness to burn. higher octane rating means a higher resistance to detonation
vapor lock
when fuel vaporizes in the lines causing a blockage of fuel flow. can starve engine of fuel leading to stoppage
what are the different types of contaminations
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
what is the most common use for Jet B fuel? what makes it so undesirable
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).
what is defueling
when an aircrafts fuel system is completely flushed out. usually due to a contamination
what are the different types of fuel pumps
mechanically driven
piston type - high pressure
diaphragm type - low pressure
different types of fuel valves
hand operated
motor operated
solenoid operated
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?
Crossfeed. funnels fuel from full tank directly into effected engine to allow for propper operation while preventing any further fuel loss
Volatility
measure of a fuels ability to change from liquid to a vapor
Viscosity
measures a fuels resistance to flow. fuels with higher viscosity retain contaminants.
entrained water
water that has become suspended within the fuel. only happens to more viscus fuels
what causes fuel fitler clogging? how can it be prevented?
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
Surfactants
Surface Active Agents - Soapy detergents that form naturally in fuel. appears as a tan to dark brown liquid
When dealing with Volatile fuels such as AVGAS and Jet B, what is a good safety precaution to follow?
always bond fuel to the truck and ground both vehicles to earth
what class of fire extinguisher is best for fighting fuel fires
Class B - Combustible liquids
what would be the most common reasons to defuel an aircraft?
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.
what common practices are used to deter misfueling
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.
AVGAS can be used in a turbine engine with minimal consequences however jet fuel can not be used in a turbine engine. why not?
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.
