Sub Module 7.17: Fueling of Aircraft

EASA  MODULE 7A
Sub Module 7.17
AIRCRAFT HANDLING AND STORAGE

AIRCRAFT FUELING PROCEDURES

The use of the term ‘fueling’ can include both refueling and defueling procedures and these notes contain examples of the essential points to be considered when refueling and defueling aircraft.
There may, however, be some further, local instructions, regarding the responsibilities of the various personnel involved in fueling procedures and these will always take precedence in conjunction with the relevant Maintenance Manual.

Refueling

When refueling the AMM should always be consulted so that the positions and capacities of the fuel tanks and also the type of fuel, position of the refuelling point(s) and refuelling procedures are known. There are two general re-fuelling methods:

1. Gravity or over-wing refuelling: which is, essentially, the same method as used to refuel a motor car (automobile), with a similar type of refuelling hose being used. As the name suggests, the filler points are, generally, on the upper surface of the wing and the tank is open when refuelling is done.

2. Pressure refuelling: in which the fuel may be pumped into the aircraft via a pressure refuelling coupling at very high rates. The refuelling pressures and the rates of fuel delivery may be quite different for individual aircraft types, so great care must be taken, to ensure no damage occurs to an aircraft through incorrect refuelling settings.
 

Checking fuel contents

This is normally done, using the aircraft fuel gauges, which may be calibrated in kilograms (kg), gallons (Imperial or US) or pounds (lb). If a double check is required, then the contents may be determined, on the ground, by using ‘dip sticks’ (installed into the top of the tanks) or by ‘drip sticks’ (or magnetic ‘drop sticks’) which are installed in the bottom of some aircraft tanks.

The aircraft fuel gauges will normally be positioned on the flight deck, but they can, on some aircraft, be duplicated at a fuelling panel, adjacent to the pressure refuel coupling. The Relative Density (RD) of fuel will vary with temperature and so the weight of a certain quantity of fuel will also vary. For example, ten gallons (Imperial) of fuel, with an RD of 0.8, will have a weight of 80 lb, while ten gallons (Imperial) of fuel, with an RD of 0.78, will weigh 78 lb. It is crucial, for balance purposes, that the weight of fuel is known and this is the reason why many aircraft fuel gauges are calibrated in units of weight rather than in volume.
 

When fueling aircraft, it is essential that the technician is aware of the RD of the fuel, so that the necessary weight calculation may be done, if necessary.

De fueling:

Occasionally, it is necessary to remove fuel from an aircraft, to facilitate fuel tank maintenance, or because the aircraft is too heavily loaded for the next flight. Removing fuel from an aircraft can be accomplished by either the gravity or by the pressure defueling method. The gravity method entails draining the fuel into a suitably earthed container, and this is typical of light aircraft, which are normally ‘gravity’ refuelled. The fuel removed must be disposed of in the correct manner, with regard to local instructions and to the environment. Aircraft that are normally pressure refuelled are normally equipped with a pressure defueling facility. Pressure defueling is achieved by utilising a small negative pressure (suction), which effectively draws the fuel out of the tank and returns it into the fuel tanker (bowser).

Current rules will normally only allow the fuel, removed from an aircraft, to be placed into a dedicated defueller vehicle and the fuel will not be permitted to be used in another aircraft. This
ensures that any contamination such as water or debris will not be transferred to other aircraft.

Fuelling Safety Precautions 

Particular care must be taken when fuelling aircraft, so that the operation may be accomplished in the safest possible manner. Whenever possible, aircraft should be fuelled in the open, and
not in a hangar (although this is, sometimes, necessary as part of a maintenance programme). This will minimise the fire risk from high concentrations of flammable vapours.
Fire appliances should be readily available during all fuelling operations. Carbon dioxide, or foam, extinguishers are recommended but, if there is a perceived increased fire risk,
then fire-fighting vehicles should be standing by. Within the specified danger area, around an aircraft being fuelled, no sources of ignition or sparks should be allowed and no electrical power should be switched on or off during the fuelling operation. It is vital that the correct type and grade of fuel is used for the fuelling operation. Use of a turbine fuel in a piston aircraft will certainly cause an engine malfunction, or failure, that could lead to loss of an aircraft. The correct type and grade of fuel is always detailed in the Maintenance Manual and marked
adjacent to the aircraft’s fuelling point(s).

Care should also be exercised so as to avoid contamination of the fuel system with water or other contaminants. The fuel supply should be regularly checked for water contamination and
a sample of fuel drained off after refuelling, so that a water check may be done. It will sometimes be necessary to filter the fuel during over-wing refuelling, particularly in dusty climates.
 

Electrical bonding of the fuel system is vital during fuelling operations, as when fuel flows through the refuelling hose, static electricity may be generated. This may lead to potential differences at adjacent metal parts and initiate a spark, fire or explosion. To minimise this risk the following actions should be completed before fuelling operations commence

1.The aircraft should be earthed
2.The refuelling tanker should be earthed
3. The nozzle of the fuel hose should be electrically bonded to the fuelling point.

EASA ESSAY QUESTION MODULE 7:

Write down the safety precautions that must be followed for refueling an Aircraft.

(Note: write your answer in the comment section below.)