Aviation Fuels: Properties and Usage

• W1 has 7 hours
• W2 has 7 hours
• W3 has 10 hours
• W4 has 10 hours
• W5 has 8 hours
• W6 has 8 hours

Fuel Types and Characteristics:

• Two main fuel types are AVGAS (gasoline) and Jet Fuel (kerosene type).
• Both AVGAS and Jet Fuel are distilled from crude oil and consist of hydrocarbons.
• A distillation process is used to refine the fuel.
• Heavier byproducts from the distillation process include kerosene, diesel fuel, and furnace oil.
• Baffles in fuel tanks and other systems help direct the flow of liquids and gases.

AVGAS:

• Used in reciprocating piston engines
• It is very volatile and extremely flammable with a low flash point.

Turbine Fuel:

• Has a higher flash point, making it less flammable.
• Exhibits higher volatility and higher flammability than AVGAS.

Volatility:

• Is the tendency of a liquid to turn into vapor.
• Low volatility means the liquid vaporizes slowly, potentially causing hard engine starting, slow warm-up, and poor acceleration.

Vaporization:

• Occurs when ambient pressure decreases and ambient temperature increases.
• Fuel that is too volatile can cause detonation and vapor lock.
• AVGAS is blended to limit its tendency to vaporize, especially at high altitudes, ensuring smooth engine performance.
• The Reid vapor pressure tester measures fuel volatility.

AVGAS:

• Can experience problems like vapour lock, carburetor icing, and detonation.

Vapour Lock:

• Is a condition in which AVGAS vaporizes in the fuel line or carburetor.
• Can result from excessively hot fuel, low pressure, or excessive turbulence.
• Vaporized liquid fuel can block the flow to the carburetor.
• The main causes are low atmospheric pressure, high fuel temperature, and excessive fuel turbulence.
• High altitude and low pressure lowers the boiling point.
• Heat from the engine can cause boiling of the fuel in the lines, leading to fuel turbulence as fuel mixes with air.
• Proper maintenance like keeping fuel lines away from heat and using boost pumps will reduce the chance of vapor lock.

Carburetor Icing:

• Occurs when vaporizing fuel extracts heat from the surrounding air.
• More volatile fuels cause more rapid heat extraction.
• The vaporization of fuel primarily happens in the venture(i) throat or throttle valve of the carburetor
• It is especially dangerous when rapid temperature decrease occurs and freezes incoming moisture
• Carburetor icing typically forms between 30°F to 40°F (-1.1°C to 4.4°C).

Detonation:

• A rapid and uncontrolled fuel explosion is caused by over temperature and is heard as an engine knock or ping.
• Can be reduced by increasing the octane rating of the fuel.

Octane Rating:

• Is an anti-detonation or anti-knock quality.
• Fuels with a higher octane rating can withstand more compression without detonating.
• Tetraethyl lead is added to increase octane rating.
• 80/87 grade AVGAS is red.
• 82UL (unleaded) grade AVGAS is purple.
• 100/130 grade AVGAS is green.
• 100LL grade AVGAS is blue.

Fuel Mixture:

• Refers to the amount of fuel versus air in the engine mix.
• A lean mixture has more air, while a rich mixture has more fuel.
• Lean mixtures tend to burn hotter then rich mixtures
• Octane ratings are lower for lean mixture settings

Numbers:

• 80/87 has two numbers, the first indicating lean mixture rating, and the second indicating rich mixture rating.
• 80/87-octane fuel is for low compression engines.
• 100/130-octane fuel is for higher compression engines.
• 100LL stands for low lead

Flash Point:

• The lowest temperature at which a volatile liquid can vaporize.
• Flammable fuels have a flash point below 38°C, while combustible fuels have a flash point above 38°C.
• AVGAS has a flashpoint of -27°C.
• Jet A has a flashpoint of 38°C.
• Jet A-1 has a flashpoint of 38°C.
• Jet B has a flashpoint of <38°C.

Turbine Fuel Properties:

• Have more sulfur and use heavier hydrocarbons than AVGAS.
• Jet A/Jet A-1 is a kerosene blend.
• Jet B is a kerosene and gasoline blend used in cold weather.

Turbine Fuel Volatility:

• High volatility is need ed for cold weather starts but high volatility can create Vapour Lock
• Turbine is less volatile than avgas.
• JET A has freezing point of -40°C for USA and Canada)
• JET A-1 has freezing point of -47°C for is used everywhere)
• JET B has freezing point of -50°C (alaska, russia and northern Canada)

Turbine Fuel Problems:

• Can be caused by water and micro-organisms.
• Water can condense out of air in storage tanks, airline fuel trucks and aircraft fuel tanks.
• Dissolved water is water that dissolves in aviation fuels.
  • Dissolved water cannot be removed.
• Free water;
  • Appears as slugs or droplets around the fuel.
  • Entrained water has a cloudy appearance
  • Large water slugs can cause engine failure
  • Ice from entrained water can restrict fuel flow by blocking fuel filters
• Low fuel temperature can be preheated before going into the engine using 'hot bleed air'.
• "Prist" is an anti-icing additive to lower the water freezing point

Micro-organisms:

• Additives and elimination of water can prevent algae or other microbial growth
• Water in fuel fuels algae, bacteria and mold

Desirable Turbine Fuel Characteristics:

• Able to be pumped and flows easily under all operating conditions
• Be efficient burn under all conditions
• Permit engine start under all conditions
• Has a high calorific value
• Be minimally corrosive effect on fuel system components
• Provide lubrication for the moving parts of the fuel system
• A minimum fire hazard
• Produce minimal harmful turbine/combustion effects

Fuel Properties

• The "calorific value" is the amount of heat released during its combustion
• Controlled specifically via gravity and volatility factors
• Viscosity indicates resistance to fluid flow
• Relighting, combustion efficiency, carbon formation, engine component life
• Specific gravity measures the ratio of density of turbine fuel to density of water at a specified temperature where high temperature cause the turbine fuel to expand

Other Fuels:

• MOGAS (automotive gas) has looser manufacturing specifications
• Physical/chemical property differences lead to poor fuel distribution, excessive oil-dilution
• More volatile than AVGAS more prone to vapor lock and carb icing ethanol is added
• Ethanol free mogas exists, it is becoming more readily avaliable, and used in diesel aircraft

Fuel Tanks:

• These three type of tank are Welded/riveted metal tanks, Integral/structural (wet wings), and or Rubber bladders

Fuel Tank Requirements:

• Fuel cannot react with aviation fuels.
• Sumps and drains must be at lowest point.
• Vents are required.
• Baffles are required to eliminate surging issues
• Ports hold up to 2% fuel expansion.
• Jettison valves might be incorporated in larger tanks
• Canada has landing gear that can land with full tanks
• You can test tanks with MLI (magnetic level indicator)
• Inclinometer for pitch and roll, used with manual checks

Properties of Fuel Tanks:

• Rigid steel or Alloy with sealant or solder seams
• Structural tanks are wings made of upper and lower skin components
• Bladder tanks are made of neoprene and attach via straps/clips

Filter Caps:

• Located at top of fixed wings and fuselage in helicopters
• The o-rings can cause contamination or spillage
• Vent holes must be kept clear
• Goose necks need to face forward
• Electronically bonding to the airframe and must provide direction
• The non-siphoning cap adapters fuel nozzle pressure

Fuel Lines:

• Can either be rigid or flexible
• 5052 aluminum alloy with AN or MS fitting, stainless steel fittings, and flareless fittings are used.
• Synthetic rubber interiors consist of synthetic exterior wraps fiber

General Fuel Line Rules:

• Separate fuel and electrical lines, no clamps
• Fuel line should not drip on electrical line
• Bonded and grounded to aircraf
• Supported no stains + aligned

Fuel Valves:

• Valves can have 3 main functions; Shut-off valve, selector, and crossfeed
• They are three main types: Manual, motor operated, and Solenoid
• Manual control (plug type) is difficult to use
• Manual gate: Fire controls that need no power
• Manual (poppet) are selector valves that provide feedback
• Most fuel systems must store and deliver clean fuel to the engine at adequate power for conditions
• These must be gravity or pump

Fuel Pumps:

• Low/midwing needs pumps to tanks
• Engine Primary Driven, or auxilarly powered (positive pressure)
• Hand operated (wobble), transfers between tanks
• Centrifugal-Boost is common
• Ejector works off Bernoulli
• Electric pumps use a solenoid
• Vane pumps transfer through reciprocating

Fuel Contaminants:

• Fuel can be contaminated by water, solids, surfactantsm micro-organisms, and other substances
• Water is a common issue that easily freezes, blocks fuel lines, and throws off quantifications.
• Solids cause blockages in meters, injectors, and nozzles.
• Surfactants are naturally liquid.
• Micro-organisms causes slime seals and cap erosion.

Fuel Tank Maintanence:

• Control by testing and filter
• Fuel filters/strainers used to deliver free contamination-free fuels

Types of Fuel Filters:

• Fuel strainers are large-sized to prevent blockage.
• Fuel filters can be fine mesh.
• Turbine engine units are close tolerance
• The filters capture particles of (10-25 microns)
• Some have popout bypass inidcations

Refueling:

• Refueling is accomplished with trucks or Hydrant ground located fuel sources
• Static electricity buildup in clothing is bad
• Bonding or grounding with cables is important

General Rules of Refueling:

• Always fuel outside
• Refuel with over the wing or Pressure
• Over wing is more dangerous

De-Fueling:

• This task is performed via tank boost pumps or pump trucks
• Drained through tank sump drains

Fuel Leakage Classification:

• Surface area is used as leaked classification standard over 30 min
• Less than 1/2" = Stain
• Less than 1 1/2" = Seep
• Area from 1 1/2" to 4" = is heavy
• A running leak is immediate and must be ground

Types of Fuel Systems:

• Piston Engines use Carburetor fuel systems
• Helicopters contains tanks near the main rotor mast and are located near AFT
• Transports carry redundant integral tanks
• EMPTY for fuel storage
• Vent config depends on board direction

Emergency aircraft exits:

• Transports that carry more than 44 people must have crash escapes within 90 seconds.

Emergency Exits requirments:

• No obstructions
• Viewable
• Simple open system

Escape:

• No engine hazards, prevent jams from fuselage damage
• Emergency exists depend on PAX

4 Types of Safety

• Exits include
• A = 110 people
• B = 75 People
• C = 55 People
• D = 45 People
• Remove bar, attach cable to door, then aircraft.
• Automatic door springs or remove bar
• All transports have the slides or the doors

Types of Evacuation slides:

• Explosive, inert gas inflation
• Faa in Canada require the aircraft evacuates in 90 secounds
• Slides must be ready in under 6 seconds

Airspeed:

• Airspeed is increased with cylinder tubes
• 750 cylinders fill slides

Emergency Lighting and ELT:

• Oxygen; lost of oxygen can cause sluggish, hypocia is a loss of oxygen
• Only 21% of oxygen
• Overcome reduced with atmospheric pressure; pressure or the air in mixture

Oxygen:

• Pressure transport in the cabin
• Quantity and indicated altitude
• High pressurised cylinders 1800-2400 psi, they are either green or aluminum.
• The tanks often have a relieve valve
• Main types of flow are continuous, alternate or pressures.

Emergency Lighting:

• A crash will trigger illumination in the cabin, the systems MUST be indpendent
• Include an emergency exit.

Crash Lighting:

• Must have read lights @ 1/2 ", ares 21 "
• Electrically brighness 400 microlamberts
• Lighting less than 0.05 foot

More on lighting in an emergency:

• <6" of passenger
• More than aft need guidance
• It must have emergency lighting as well
• They will need power systems and operate independently

Components to an independent power source for Crash System

• Black part in back is battery
• Rechargable during normal.

Emergency Locator transmitter (ELT):

• This is an independent battery powered transmitter that activates by G
• 2009 it changed to 406 MHZ

Emergency Locator transmitter (ELT) Function:

• Digital signal every 50 sec at 5w @ 24 hours
• Triangulation w/ position
• 2nd gerneration GPS data

Emergency Locator transmitter (ELT) Location:

• Located in the aft and should be done w/ avoon shop with the aircraft
• Must tested, it is either located on panel
• The ON position will trigger
• OFF will shut of

Underwater locator:

• Deivce on CVF and FAR
• emits a ultrasound and can be recovered

Fire Detection Principles:

• Fuel, and air

Classes of fire and NFPA:

• A = Wood, paper, cloth
• B = grease oil, paint, solvents etc
• C = Electricity
• D = magnesium
• K = Vegitable oils

Emergency aircraft fire:

• Zone fixed equipment is required
• engines and APU or lavs and electronic
• Classes: A power = section turbine engine. B = aeroclean. C relatively low airflow, APU
• D very little airflow wings and wheels

Detection systems:

• Overheat are Spot continuous; Single switch tube
• Continuous loop; Single switch in the form of a LONG inconel tube instead of several switches

Fire systems:

• Fenwal produces a thermocouple system
• Thermal is one aircraft lighting, is heats up more sensitive relay

Fire Systems metals: HOT junc

• Junction heat quickly reference
• Hot 4 milliamperes the size fire. 5ohms
• Continuous loop sensing elements
• Fenwal wire. Connected in SERIES
• Wire to employ loop. Euteitic out alarms open overheat

Kidde Continuous Loops:

• 2 wires with thermastor
• Decrease indication in flight deck
• TEST integrity w/ 2 fire
• Selectors to use fire at the moment

Pneumatic continuous loop:

• Both cause average gellium. Heat operation
• The fire sensors contain Hydrogen gas and the pressure alarms

Carbon Monoxide alarms:

• Indicate smoke in the cabin with a Photoelectric and Solid state alarm
• These detect gas warnings.
• A chemical tans will go gray. The presence will determine

Flame and Fire:

• Fire detector consistens of a photoelectric with radiation in enclosed
• Fire Extenguinshins. fire extingusing fire
• Car bon dioxide pushes away
• Used with Class b/c. Cannot use magnesium of titanium
• Use Halon
• Aviation grants

Halogenated Hydrocarbons

• Halon 1301 safest total flooding
• All portible need access. Look up yearly must check.
• High rate use, light weight w. Sphere
• Has bonnet multippel agent
• Two shot under std required 2 dump
• CArgo activated can check level

Lav:

• 20 people detector auto trigger. 170' solder.

Explore aviation fuel properties like flammability, vapor lock, and grade determination. Understand the function of additives such as tetraethyl lead (TEL). Learn about identifying appropriate fuel for specific engine requirements and conditions.