Aircraft fuel Flashcards
(27 cards)
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
