Fuel Systems

Question 1

3 different types of fuel tanks

Answer 1

Integral

Flexible/bag

Rigid/drum/fabricated

Question 2

Integral tank and adv and disadv

Answer 2

Built into the wing

Saves weight and efficiently utilises space

Maintenance might be difficult

Question 3

Flexible/bag tanks and adv and disadv

Answer 3

Rubber and fabricated bags

Self sealing

Easy to maintain

Question 4

Rigid/ drum/ fabricated tanks and adv and disadv

Answer 4

Rigid - made of aluminium, riveted/welded together

Cheap

Adds weight

Can take them out to get to components behind it

Question 5

A vent surge tank is located

Answer 5

Out towards the tip

Question 6

Name microbiological fungus in the fuel and risks

Answer 6

Cladasporium resina

Can grow to block fuel systems

Question 7

Different AVGAS and colours

Answer 7

AVGAS LL = blue

AVGAS 100 = green - high tetchric Ethal lead content

AVGAS 80 = red - low compression ratio engines/ older piston engines - lower octane rating = lower resistance to detonation

Question 8

Different types of AVTUR and the difference in waxing points between them

Answer 8

Jet A1 - has a FSII icing inhibitor - lowers the waxing point to -47C - flash point of 42C

Jet A - waxing point of -40*C

AVTUR is a diesel and a narrow cut fuel

Question 9

Cloudy fuel can indicate

Answer 9

The fuel is contaminated with water or some other form of contaminate

Question 10

Jet B fuel

Answer 10

Wide cut

Low flash point

Waxing point of -60*C

Blend of AVGAS/AVTUR = AVTAG

Question 11

Collector box

Answer 11

Collects fuel in and doesn’t let it out again - allows you to maintain constant fuel while doing manoeuvres

Used in a float type fuel system

Question 12

Booster pump in a light a/c fuel system

Answer 12

Electric - makes user you have a constant fuel to the engine driven pump
Fuel cooled
LP centrifugal pump
Electric motor AC 400hz - switched by DC but powered by AC
Pressure = 25-50psi
High flow rate capacity

Question 13

The gauge on a fuel float tank and when is it most accurate

Answer 13

Of the resistive type

Most accurate - flying straight and level

Question 14

Why are the tanks pressurised

Answer 14

To stop them from boiling at altitude

Ram air gives a slight positive pressure in the tanks and helps reduce vaporisation at high level

Question 15

Purpose of the venting system in the fuel tanks

Answer 15

Allows air to escape during re fuelling

Allows air to enter during fuel usage

Question 16

Purpose of the vent surge tank

Answer 16

Collects droplets of fuel from the vent air and, hence reduces the losses from the vent system by returning this fuel to the tanks

Question 17

If their is a fuel imbalance - pilot actions

Answer 17

Make sure the booster pump is working
Put the crossfeed valve on
Switch off one side of the booster pumps

Will drain from 1 side only

Question 18

Capacitance system operation

Answer 18

Uses a number of low voltage cylindrical capacitor probes

Capacitance depends on how much of the probe is submerged - compensator measures the dielectric

Fuel densitometer measures the density - system knows volume/density so it can work out mass

Question 19

If their is a malfunction with the capacitive gauging system the gauge will

Answer 19

A fail safe circuit is introduced which drives the gauge pointer SLOWLY towards the empty posn

Single sensor failure has no effects - will only get a light on the f/d

Question 20

The needle on the ff meter when push to test is operated will

Answer 20

Drive towards 0 then go to the correct value

Question 21

Fuel flow indicators are fitted

Answer 21

After the engine shut off valve, between the fuel control unit and the engine

Question 22

For fuel jettison - what must be operated in the f/d

Answer 22

Need to open fuel jettison and the master jettison valve

Question 23

Automatic dumping is stopped when

Answer 23

When at low fuel levels

Can be overridden manually

Question 24

Refuelling systems - difference between light and transport a/c

Answer 24

Gravity for light a/c

Pressure for large transport a/c

Question 25

SG of AVGAS and Jet. A1 and B at 15*C

Answer 25

AVGAS = 0.72

Jet A1 = 0.8

Jet B = 0.77