7.17 Refuelling and Defuelling

Question 1

What are the 2 main categories of aviation fuels?

Answer 1

• Aviation gasoline
• Turbine fuels

Question 2

What is the short version for Aviation gasoline?

Answer 2

AVGAS

Question 3

What is AVGAS formulated to do?

Answer 3

Burn smoothly in piston engines without detonation or knocking

Question 4

How is AVGAS graded?

Answer 4

By its octane number

Question 5

What does the octane number indicate?

Answer 5

The fuels resistance to knocking, the higher the number the more resistant it is

Question 6

What different gradients are what colour?

Answer 6

80 - Red
100 - Green
100LL (Low Lead) - Blue

Question 7

What are turbine fuels used to power?

Answer 7

Gas turbine engines

Question 8

What are the different types of turbine fuels available?

Answer 8

• Jet A
• Jet A-1
• Jet B

Question 9

What are the different freezing points of turbine fuels?

Answer 9

Jet A – Freeze point -40 °C (-40 °F)
Jet A-1 – Freeze point -47 °C (-52 °F)
Jet B – Freeze point -50 °C (-58 °F)

Question 10

What colour are turbine fuels?

Answer 10

All colourless or a light straw colour

Question 11

What are the 2 types of refuelling methods?

Answer 11

• Gravity or over-wing
• Pressure refuelling

Question 12

What is gravity or over-wing refuelling?

Answer 12

When the aircraft is refuelled from the top of the wing like a car

Question 13

What is pressure refuelling and its advantages?

Answer 13

• Uses receptacles in the leading edge of the wing to fill the tanks
• Decreases time to refuel
• Limits contamination
• Reduces change of static electricity igniting fuel

Question 14

What are the refuelling and defuelling pressures for pressure fuelling?

Answer 14

Refuelling - 50 psi or 1000 gallons (4546 litres) per minute
Defuelling - 11 psi

Question 15

What are the 2 methods of defuelling?

Answer 15

• Gravity
• Pressure

Question 15

What is gravity defuelling?

Answer 15

Draining the fuel into a suitably earthed container

Question 16

Where is gravity defuelling normally done?

Answer 16

On light aircraft

Question 17

How is pressure defuelling achieved?

Answer 17

By utilising negative pressure, which sucks the fuel out of the tanks or by using the aircraft fuel pumps to pump the fuel out

Question 18

What happens with the drained fuel and what can you not do and why?

Answer 18

You cannot put it back into another aircraft as this can cause contamination like microbiological growth, water or debris

Question 19

How would you be able to put drained fuel back into the aircraft?

Answer 19

If the company has a concession allowing the fuel to be put back in an aircraft

Question 20

What is the main priority when fuelling?

Answer 20

The safety of everyone in the area and on the aircraft

Question 21

What must the fuel provider have?

Answer 21

All the necessary PPE and fire-fighting equipment at hand

Question 22

What are 2 of the essential safety precautions when fuelling?

Answer 22

• Grounding and bonding of both the aircraft and the fuel truck
• Respecting the fuelling safety zone

Question 23

Why can a static discharge be dangerous?

Answer 23

Because it’s a potential source of a spark and therefore ignition

Question 24

What is done to prevent static discharges from injuring people?

Answer 24

Electrical bonding and/or earthing

Question 25

How does Electrical bonding and earthing stop static discharge?

Answer 25

It neutralises differences in electrical potential between refuelling components or the aircraft

Question 26

What does grounding do?

Answer 26

Ensures electrical continuity between the aircraft and the earth

Question 27

Where can grounding points be located?

Answer 27

- On the Nose Landing Gear (NLG) - On the Main Landing Gears (MLG) - On the wings - On the engine air inlet - At the High Pressure (HP) connector

Question 28

What does bonding do?

Answer 28

Ensures consistent flow of electricity between the aircraft and the fuel vehicle, preventing any sparks

Question 29

How do you accomplish bonding?

Answer 29

By using a dedicated cable to link the aircraft to the fuel truck

Question 30

What must be established when refuelling?

Answer 30

Safety zones, all personnel need to be aware of them

Question 31

What do safety zones include?

Answer 31

An escape route for the refuelling vehicle

Question 32

In smaller operations and airfields who is it up to to ensure the fuel vehicle has an adequate escape path?

Answer 32

The aircraft engineer

Question 33

How big is the safety zone around a vent duct with an NACA duct and why?

Answer 33

3 metres as fuel can flow out of these

Question 34

How big is the safety zone around overpressure protectors and refuel couplings?

Answer 34

3 metres

Question 35

What are the fuelling safety precautions?

Answer 35

- Approach the aircraft with caution, positioning the fuel truck to allow for quick truck departure in an emergency. Set the hand brake of the fuel truck and chock the wheels to prevent rolling. - Ground (earth) and bond the aircraft and fuel truck - No smoking signs must be displayed at a minimum distance of 15 m (50 ft) from fuelling equipment and aircraft tank vents. - Fuelling zones should be established before fuelling/defuelling commences. These zones should be regarded as extending at least 6 m (20 ft) radially from the filling and venting points on the aircraft and fuelling equipment. - Aircraft must be fuelled in the open and not in a hangar whenever possible. - Fire appliances must be readily available when all fuelling operations are taking place. - The correct type and grade of fuel are required for the fuelling operation. The type and grade of fuel must be marked adjacent to the filler point(s). - Care must be exercised to avoid contamination of the fuel system with water or other sources of contamination. The fuel supply must be regularly checked for water contamination. - The Ground Power Units (GPUs) must be as far as practical from aircraft fuelling points and vents. - Fuel bowsers normally position themselves facing away from the aircraft being refuelled for rapid emergency evacuation. A clear exit must be maintained. - Aircraft engines must not be operated. - People and vehicles within the fuelling zone must be kept to a minimum. - Fuelling is suspended during electrical storms in the vicinity. - If any fuel spillage occurs, it must immediately be cleaned up and the material used for the cleaning must be disposed of correctly. - The connection between the refuelling hose and the aircraft can be either a sealed coupling, as used when pressure refuelling is required, or a hand-operated nozzle similar to a garage pump. They both have a separate earthing lead with either a connector or a crocodile clip attached. - Whilst it can be necessary to have some form of electrical power switched on during the refuelling or defuelling operation, only the minimum necessary for refuelling/defuelling must be switched on. No radio or radar equipment is to be operated whilst refuelling or defuelling is taking place. - Due to the high pressures involved with pressure refuelling, any pre-refuelling checks of the shut-off mechanisms must be serviceable. The operator must also be ready to shut off the flow at the first sign of a problem. - Ground equipment must be moved away from the aircraft to prevent damage as the aircraft settles due to its increased weight. - During refuelling, the tyres expand, and the landing gear oleo struts settle. Therefore, the chocks must be located slightly away from the wheel during the actual refuelling operation. - After refuelling an aircraft, it is usually recommended that the fuel is checked for contamination. - Drain valves are provided in the lowest parts of the fuel tanks and major components to allow small amounts of fuel to be drained into a suitable transparent container. Any contaminants in the fuel must be visible in the container. With turbine fuels having a slow settling rate, it is best to wait for the longest period possible before carrying out a drain check on the fuel. - Perform a water check on the fuel.