Fuel ⛽️

Question 1

AVTUR qualities

Answer 1

High calorific value
Low freezing temperature
Flows across a wide range of temperatures
Assists in lubrication

Question 2

AVTUR flash point

Answer 2

38C-60C

Question 3

AVTUR freezing temp

Answer 3

-47C

Question 4

Specific gravity of AVTUR

Answer 4

0.8kg

Question 5

AVGAS freezing temperature and flash point

Answer 5

Freeze -100C
Flash 38C

Question 6

What is bio jet fuel

Answer 6

Renewable fuel derived from biomass (plants, algae, animal shit). Also called sustainable aviation fuel SAF.

Question 7

JP means

Answer 7

Jet propellant

Question 8

Jet A freezing temperature and where it’s used

Answer 8

-40C
Used in USA since 1950s and unavailable outside USA and Canada

Question 9

Jet A-1 freezing point

Answer 9

-47C

Question 10

What is the military equivalent of jet A1 and what additives does it contain

Answer 10

JP-8
It contains corrosion inhibitor and anti icing additives
NATO CODE F-35 and F-34 depending on the additives it contains

Question 11

What is JP-5

Answer 11

The aircraft carrier equivalent of Jet A1
Also known as AVCAT.
It contains no anti static agents
NATO CODE F-44

Question 12

What is the primary difference between JP-5 and JP-8

Answer 12

Flash point difference
JP-5 is 60C
JP-8 is 38C

Question 13

Properties of Jet B and its military code

Answer 13

JP-4
NATO code F-40
Only used in very cold climates as it is very dangerous to handle
Consists of 70% gasoline and 30% kerosene

Question 14

Why won’t AVGAS work in a turbine engine

Answer 14

Lead deposits on the turbine blade causing imbalance and damage through vibration
Doesn’t have the lubricating properties of AVTUR
Will cause detonation due to its high flash point

Question 15

What is the definition of specific gravity (relative density)

Answer 15

The ratio of a substance to water at 4C

Question 16

Auto ignition temperature of AVTUR

Answer 16

210C

Question 17

What temperature is AVTUR kept at in the fuel tank

Answer 17

At least 3C warmer than its freezing point

Question 18

How does entrained water appear in an AVTUR fuel sample

Answer 18

Dull or hazy

Question 19

Where does a fuel flow meter electronically send its readings from

Answer 19

Low pressure part of the fuel system

Question 20

What does the low pressure fuel pump do

Answer 20

Pumps from tank to fuel heater/oil cooler, ensuring constant fuel supply. Generally are a centrifugal type pump

Question 21

What does the high pressure fuel pump do

Answer 21

Follows on from the low pressure fuel pump and sends from the fuel heater/oil cooler to the fuel control unit FCU. Surplus fuel is returned to the pump inlet by the FCU
Usually is a gear type fuel pump

Question 22

Multi plunger /smash plate type fuel pump properties

Answer 22

Is a variable displacement pump
The output depends on rotational speed and reciprocation action of pistons

Question 23

What does the FOHE fuel-oil heat exchanger (fuel heater/oil cooler) do

Answer 23

Warms fuel to prevent freezing while also keeping the oil at a good temperature

Question 24

Coarse fuel filters (>40microns) are fitted between which components

Answer 24

Pump and tanks

Question 25

Fine Filters (>10microns) are placed between which components

Answer 25

Fuel pump and FCU

Question 26

How does the FCU adjust fuel flow

Answer 26

Power lever position
Current Engine rpm
Inlet air pressure and temperature
Combustion chamber pressure

Question 27

Ideal fuel air ratio by weight

Answer 27

15 parts of air to 1 part fuel

Question 28

What does a governor or limiting device do in a turboprop

Answer 28

Uses a gas generator to prevent the core and prop from overspending in a prop pitch failure