Aircraft Fuel Systems

Question 1

What is the purpose of a fuel system?

Answer 1

To carry the amount of fuel required for a mission. Including reserves.
To supply the engines with fuel in quantities and with pressure required

Question 2

What is needed to determine the size of a fuel system?

Answer 2

Required volume of fuel (fuel loading capacity)
Limitations in shifting of aircrafts COG
Min and max fuel flow rate
Limitations in pressure differences at engine fuel injection port

Question 3

What % of Mtow is fuel?

Answer 3

Between 30-45%

Question 4

What are the types of fuel tanks?

Answer 4

Rigid Reservoirs (Internal or External)
Flexible Reservoirs (Sacks in a special housing)
Integral Reservoirs (Part of structure)

Question 5

What is the purpose and location of “Tip Tanks”?

Answer 5

Tanks at wing tips

Fitted for extending range/transfer flights

Question 6

Which angular motion affects “Tip tanks” the most?

Answer 6

Roll

Question 7

+ and - of wing fuel tanks?

Answer 7

+: Integral reservoirs utilise already available free volume, Tanks COG is close to planes COG, Acts as counterweight, reduces structural load in wing
-: Increases moment of Inertia in x-axis (Roll), Very little volume available in supersonic aircraft due to thin wing section, Large vulnerable area exposed to projectiles (combat aircraft)

Question 8

How can we refuel an aeroplane?

Answer 8

Ground refuelling

Air Refuelling

Question 9

What should happen to fuel on emergency landing? Which subsystem is responsible for this?

Answer 9

It should be jettisoned using the fuel dumping system

Question 10

How to measure the quantity of fuel in reservoirs?

Answer 10

It is done by checking the volume of the fuel in the reservoirs, inclusive of the temperature effect correction. The volume is indicated by fluid level measurements

Question 11

Describe the working principle of any fuel probe?

Answer 11

They sense the level of the fuel in the tank