15.11 - Fuel

Question 1

Duplex nozzle

Answer 1

Dual manifold

Question 2

Simplex nozzle

Answer 2

Single manifold.

Question 3

Fuel nozzle mounting

Answer 3

External mounting.
- nozzle to case

Internal mounting
- at the liner dome.

Question 4

Disadvantages of the simplex nozzle

Answer 4

Can only give a good atomisation in a small fuel flow range.
For good atomisation two sets of simplex nozzles are used
- small discharge orifices for engine start up called primary nozzles.

• second set for max power and acceleration called secondary

Modern engines do not have these.

Question 5

What fuel nozzles do modern engines use

Answer 5

Duplex nozzles - dual floe nozzles.

Question 6

Do fuel nozzles have a check valve

Answer 6

Yes, to prevent carbon build up.

Question 7

FADEC

Answer 7

Full authority digital engine control.
Uses electronic sensors
Uses a fuel metering valve
The EEC is a computer that contains the operations of the engine
Cooled by convection
Has 2 electronic channels.
Uses a throttle lever angle resolver
Uses crosstalk logic to compare data from both channels.
Fuel metering unit is on front face of the gear box, attached to the fuel pump.
The programing plug stays with the engine.
The EEC receives feedback.