Aircraft fuel Flashcards
What is AVGAS or Aviation Gasoline?
- USED IN RECIPROCATING (PISTON) ENGINES
- MORE VOLATILE AND FLAMMABLE THAN TURBINE FUEL BECAUSE OF CONTINUOUS AND REPETITIVE IGNITION USED IN A RECIPROCATING ENGINE
Vaporization increases as:
- AMBIENT PRESSURE DECREASES
- AMBIENT TEMPERATURE INCREASES
THE ________ PRESSURE TESTER IS USED TO MEASURE THE VOLATILITY OF A FUEL
REID VAPOUR
AVGAS IS LIMITED TO ____ PSI ON THE REID TESTER TO LIMIT VAPOUR LOCK
7 psi
NORMALLY FUEL REMAINS IN A LIQUID STATE UNTIL IT IS MIXED WITH THE AIR STREAM, WHERE IT CHANGES TO VAPOUR
UNDER CERTAIN CONDITIONS THE FUEL CAN VAPOURIZE BEFORE IT REACHES THE AIR STREAM
Vapor lock
3 General causes of vapour lock?
Lowering pressure of fuel (High Altitudes)
High Fuel Temperature (Heat from the engine)
Excessive fuel turbulence
How to stop Vapor Lock?
-KEEP FUEL LINES AWAY FROM:
> SOURCES OF HEAT
SHARP BENDS
STEEP RISES
-BOOST PUMPS
> KEEP FUEL UNDER PRESSURE TO ENGINE DRIVEN PUMP
-VAPOUR ELIMINATORS
> INSTALLED IN SOME SYSTEMS AHEAD OF METERING DEVICE ( CARB / FCU)
What is carb icing?
- WHEN FUEL VAPOURIZES IT EXTRACTS HEAT FROM ITS SURROUNDINGS
- THE MORE VOLATILE THE FUEL THE MORE RAPID THE HEAT EXTRACTION
- THE RAPID DROP IN TEMPERATURE AS THE FUEL VAPOURIZES MAY FREEZE THE MOISTURE OF THE INCOMING AIR
How to eliminated carb icing?
-PISTON ENGINES HAVE CARB HEAT AND/OR AIR INLET HEAT, CONTROLLED BY THE PILOT, TO ELIMINATE ICE BUILDUP
What is Detonation?
A RAPID UNCONTROLLED EXPLOSION OF FUEL DUE TO HIGH PRESSURE AND TEMPERATURE
How to prevent detonation?
- IT CAN BE REDUCED BY INCREASING THE OCTANE RATING OF THE FUEL
- THE HIGHER THE OCTANE RATING THE MORE COMPRESSION THE FUEL/AIR MIXTURE CAN STAND WITH OUT DETONATING
What is added to the fuel to increase octane rating?
TETRAETHYL LEAD
Three grades of AVGAS
80/87 identified as 80 RED
100/130 identified as 100 GREEN
100LL identified as 100LL BLUE
80/87 What is the indication of the first number?
Lean mixture rating
80/87 What is the indication of the second number?
Rich mixture rating
WHICH BURNS HOTTER, A LEAN OR A RICH MIXTURE?
A LEAN MIXTURE BURNS HOTTER AND WILL DETONATE SOONER THAT’S WHY THE LOWER OCTANE RATING IS FOR THE LEAN MIXTURE SETTING
What is Turbine fuel?
- TURBINE OR JET FUEL IS MADE FROM THE HEAVIER HYDROCARBONS THAN AVGAS AND HAS MORE SULPHUR IN IT
- COLOURLESS / NO DYE ADDED (yellowish or straw-coloured hue from the sulphur)
- Less volatile that AVGAS and has different volatility ratings
What are the three types of turbine fuels?
Jet A
- Least Volatile (only used in US and Canada, -40)
- Kerosene Blend
Jet A-1
- More volatile (used anywhere)(-47 freezing point)
- Kerosene Blend
Jet B
- KEROSENE/GASOLINE BLEND FOR COLD WEATHER OPERATION
- (used only in ALASKA, RUSSIA and NORTH CANADA, -50)
High volatile is needed for _____.
COLD WEATHER STARTS AND AERIAL RESTARTS
Low Volatile is needed to _____.
reduce vapour lock
Water is always a problem in Turbine fuel, what is a DISSOLVED water?
Water forms part of the fuel just like water vapour and cannot be removed in the fuel.
Water is always a problem in Turbine fuel, what is a FREE water?
Droplets floating on the fuel and gives a cloudy appearance on the fuel.
WHEN FUEL TEMPERATURE DROPS TO BELOW FREEZING, ________ TURNS TO ICE CRYSTALS
DISSOLVED WATER
HIGH FLYING AIRCRAFT HAVE _________ TO LET THE CREW KNOW WHEN THE FUEL IS GETTING TOO COLD.
FUEL TEMPERATURE PROBES
I the temperature is too low, fuel can be preheated before going to the engine BY USING?
Hot bleed air from the engine or Engine oil
FUEL FILTERS MUST HAVE BYPASS AND ________ SWITCH TO WARN FLIGHT CREW OF FILTER CLOGGING
DIFFERENTIAL PRESSURE SWITCH
How to prevent Microbial Growth on the tank?
ADDITIVES AND THE ELIMINATION OF WATER CAN PREVENT ALGAE GROWTH.
