13.13 Fuel Systems Flashcards
What are the two types of fuel used in aircraft?
Aviation gasolene – piston
Aviation kerosene – turbo–jet and turbo–prop
What qualities should aviation fuel have?
Easy pump and flow under all operating conditions
Enable engine starting at all ground conditions and gives satisfactory relighting characteristics
Efficient combustion under all conditions
High a calorific value as possible
Minimum corrosive effects on the combustion system or the turbine blades
Minimal corrosive effects on the fuel system components
Adequate lubrication for the moving parts of the fuel system
Reduce fire risks to a minimum
What is the identification marking for AVGAS?
Single blue band followed by a red rectangle
AVGAS written in white
What is the identification marking for AVTUR?
Two black bands followed by a black rectangle with JET A–1 written in white
How do antioxidants work and what do they prevent the formation of?
Interrupting the chain of oxidation reactions
Peroxides
Soluble gums
Insoluble particulates
What are ‘chelating agents’?
Chemical compounds that form stable complexes with specific metal ions
How is FSII added to fuel?
The additive must be injected at a controlled rate into a flowing stream of fuel
When will cladosporium resinae propagate in a fuel tank?
When water is present and the temperature is between 15°C and 35°C
At what general geographical zone are conditions favourable to fungal growth in fuel tanks?
30° N to 30° S
What other artificial cause might create the ideal conditions for the growth of Cladosporium Resinae?
Modern heated hangars
What might be the cause of erratic, or false, fuel quantity indication?
Microbiological contamination
What should a refueller deliver line contain?
5 micron filter
In order to meet the requirement of delivering a supply in excess of engine demand under the most adverse operating conditions, what are these conditions considered to be?
Full power at sea level with an almost empty tank
What is ‘surge’ in relation to fuel?
Mass free movement of fuel within a tank
How is ‘surge’ reduced?
Baffles, which allow flow of fuel but reduce ‘surge’
What is a disadvantage of a rigid removable tank?
Tank must be smaller than the tank compartment to fit into the compartment
Best use of the available space is not utilised
What might baffles be called in an integral fuel tank?
Chordal diaphragms
Why are 3–phase AC fuel pumps mainly used in modern aircraft?
High flow rates that can be achieved from relatively small pumps
Why is a bypass mechanism not necessary in a LP pump?
Fuel can be drawn through a ‘stationary pump’
What are the two types of LP fuel pump location?
Fully immersed (wet bay)
External (dry bay)
What is the advantage of a ‘Canister Type Pump’?
Failure of the pump does not require draining of fuel tanks
Reduces aircraft down time
On light aircraft, where is the booster pump normally fitted?
Between the tank and the engine
What are jet pumps also known as?
Scavenge pump
Venturri pump
Where is a jet pump normally fitted, and what is peculiar about it?
Remote areas of the fuel tank
No moving parts, instead relying on the motive flow from the booster pump to move fuel
What are the conditions which require fuel venting?
Inflow and outflow of air as the aircraft changes ‘altitude’
Changes in fuel capacity as the aircraft is being ‘refuelled and defuelled’
Changes of fuel contents as the fuel is being ‘used by the engines’
Effects of temperature changes which would cause expansion and contraction of the aircraft fuel contents
Allowance to discharge excess fuel to atmosphere should the refuelling valve fail to close when the tank is filled