Safety & Cleanliness Precautions, Associated Operations during Refuelling, Water Check Operations, Magnetic Fuel Indicator Checks, Aircraft Attitude Indicator Checks, Fuel Loading Regulations and the FQI system
Concorde was pressure-refueled through two refuel control units in the under-wing fairings forward of the main landing gear bays and connected to the trim transfer pipes. Both units are fitted with two 2.5in (63.5mm) self-sealing bayonet-type couplings to which the fuel hoses are connected, permitting refuelling with four hoses at a rate of 450 gal /per minute (Imp.) (540 US gal /per minute) 2,045 litres per minute each. All the tanks can be refuelled simultaneously or each tank separately, for either partial or total filling from the refuel control panel located next to the right-hand refuel control unit. Required quantities can be pre-selected on this refuel control panel.
Part or all of the refuelling procedure is stopped in the event of overfilling, excess pressure, inadvertent opening of the trim valves or adverse rearward movement of the aircraft centre of gravity.
The aircraft was normally refuelled at a pressure of 50 psig (3.45bar) at each hose end. This pressure is however, subject to limitations. During normal refueling as already stated the pressure was 50 psig (3.45bar) at the refuel control unit (RCU) coupling. But when refuelling was being carried out at this pressure, it was essential that the fuel contains a static dissipater additive, and that hose-end pressure controllers are used. If these requirements were not met and therefore the fuel did not contain a static dissipater additive, the refuelling pressure must not have exceeded 30 psig (2.07bar). If it was not practicable to control the refuelling pressure at this reduced rate, the following alternative procedures may have had to been used:-
Check the positions of the refuel valves of the rear tanks (Numbers 2, 3, 6, 7, 5A, 7A and 11) which have been selected open.
The normal refuelling procedures assumes that all the equipment is serviceable and no failure conditions occur. In these circumstances, the refuelling completion time at the normal refuelling pressure is approximately 20 minutes.
The calculation of the aircrafts centre of gravity (C.G) position is derived from the Weight and balance Manual and it would be essential that the aircraft balance is considered at all times during refueling and loading. During a refuelling operation, the order in which the tanks are filled must be carefully monitored, to ensure that the forward tanks are filled first and then the rear fuselage tank (tank 11) is not completely filled until it is established that the aircraft C.G. position is sufficiently far forward.
Safety & Cleanliness Precautions during Refueling
Wheel chocks must be in position but placed clear of the wheels to allow for tyre spread due to increased aircraft weight.
All equipment and vehicles must have sufficient clearance to allow for aircraft sink during refueling.
All persons, equipment and vehicles must be kept clear of the overflow/relief valve outlet in the bottom surface of the rear water fuselage.
All fuel must be clean and when supplied to the aircraft must have been passed through a 5 micron filter.
Refuelling hose-ends must be fitted with suitable covers when not in use.
Associated Operations during Refueling
This subject comprises procedures for checking the water drain valves and reading the magnetic fuel level indicators, together with information on the aircraft attitude indicator.
Precautions must be taken to ensure that the fuel in the tanks has not been contaminated with water. For this purpose, 28 water drain valves are provided, one or more in each tank, at the lowest points. Water checks, using these drain valves must be carried out after refuelling. If the aircraft has been on the ground for more than 8 hours, these checks would then be carried out on the designated drain valves both before and after refueling. If significant quantities of water are found, the water drains in all the remaining tanks must be checked.
Magnetic fuel level indicators (MFLIs) are fitted in all tanks except tank numbers 1, 2, 3, 4, 5A & 7A, which are normally always filled during refuelling. These indicators provide an under-wing method of manually checking the tank content and are used when a fuel quantity indicator has failed.
An aircraft attitude indicator, using a bubble and spirit-level principle, is provided to enable a check to be made of the aircraft attitude in pitch and roll. This must be within prescribed limits to achieve accurate MFLI readings and high level shut-off fuel quantities.
Water Check Operations
The Equipment and Materials that is required to carry out these checks:-
Water Drain Tool – this is used for operating the water drain valves on the aircraft. Another Water Drain Tool with an extended handle will also be required. This allows operation of the valves from ground level.
Plastic Bottle 1.75 pints (1.0 L) – This is required for collection of the fuel sample.
Water Checking Procedure
1. At each water drain valve, depress the valve push-rod or inner valve, using the water drain tool.
2. Drain off approximately 0.9 pints (0.5L) of fuel as a sample.
3. Withdraw the tool
4. Check the sample for freedom from water contamination.
5. If water is evident, take further samples until water-free fuel is obtained.
6. Check the valve for freedom from leakage.
7. Remove contaminated fuel to a safe place for disposal.
8. If sent to a laboratory for analysis, list all known additives to enable sample to be disposed of safely in accordance with local regulations.
Checks for water contamination in the fuel must be carried out in accordance with the following requirements:-
1. If the aircraft has been on the ground for less than 8 hours, checks must be carried out on tanks 1, 2, 3, 4, 5 and 7 after refuelling.
2. If the aircraft has been on the ground for more than 8 hours, checks must be carried out on tanks 1, 2, 3, 4, 5 and 7 both before and after refuelling.
3. If tank 9 is being used for take-off, its water drain also must be checked.
4. If tanks 5 and 7 have not been refuelled, the water drains in tanks 6 and 8 must be checked instead.
5. If significant quantities of water are found, the water drains in all the remaining tanks must be checked for water contamination.
MAGNETIC FUEL INDICATOR
The magnetic fuel indicators (MFLIs), in the wing and fuselage bottom surfaces, are provided to enable a direct measurement to be made of the fuel level in the tanks.
To use the MFLI, the screwdriver slot in the stowage button must be pushed upwards and turned through 90 deg, allowing the calibrated tube (measuring stick) to be partially ejected by spring pressure. The stick has to be then withdrawn manually until resistance to further withdrawal is felt, caused by the linking of the inner and outer magnets.
The stick calibration markings (in millimeters) are read against the lower edge of the contents register, and this measurement is then converted to tank fuel load by reference to conversion tables.
The tank fuel load figure, which is obtained from the conversion table, must be corrected as necessary, by adding or subtracting the specific gravity correction factor.
To stow the measuring stick, the stowage button must be pushed fully upwards, turned through 90 deg, and then released. The button is confirmed as locked when the slot coincides with two makings on the base fitting.
One MFLI is provided in each of tanks 5, 6, 7, 8, 10 and 11. In tank 9, two forward and two aft MFLIs are provided in the wing cells. The forward MFLI sticks are used for tank loads greater than 50%, and the rear sticks for tanks loads less than 50%. With the aircraft at 0 deg roll, only one forward or rear stick is used. If the aircraft is not at 0 deg roll, either forward or rear sticks are used and a average of two readings is taken.
Since tanks 1, 2, 3, 4, 5A and 7A are invariably filled, there are no MFLIs provided.
All MFLIs are similar except that in tank 11, which is 7 feet (2.14M) in length and therefore requires a central support and two floats. This results in a 120mm ‘dead band’, at approximately mid-operation, where no fuel reading can be obtained. If the ‘dead band’ area is presented, the stick must be withdrawn further to engage the lower float. This will check weather the fuel level corresponds with, or is below the central support.
All the sticks are designed to measure between 15% and 90% of tank full level only.
The ground attitude of the aircraft, which affects the accuracy of stick readings, must be checked on the aircraft attitude indicator (SEE PICTURE BELOW) before stick readings are taken. Variations of up to 1 deg in pitch should not give errors in fuel quantity greater than +50 kg.
1. Check that the bubble in the aircraft attitude indicator is within the nominal ground attitude envelope.
NOTE: For the following procedure detailed below, the ‘Fuel Distribution on Departure’ section of a new Refuelling sheet would be required.
2. For tanks required to be full, you would have to enter the gauge readings in the appropriate spaces, checking that they are within +2% of the nominal full quantities. If the gauge reading is suspect, you would have to confirm that the tank is full, by checking that its refuel inlet valve is shut, and use the nominal full quantity, extracted from the appropriate Refuelling Schedule table.
3. Lower the appropriate stick and note the reading.
4. Convert the stick reading into kilogrammes, using the appropriate conversion table.
5. Apply the specific gravity correction factor
6. Enter the correct quantities on the ‘Fuel Distribution on Departures’ section of the Refuelling sheet.
7. Determine the total fuel on board by addition and compare the quantity with the Refuelling Sheet, Item A.
8. Check the accuracy of the fuel distribution by reference to the appropriate Refuelling Schedule table.
9. Adjust the tank quantities in accordance with the appropriate Refuelling Schedule table.
AIRCRAFT ATTITUDE INDICATOR
The indicator is mounted inboard of the refuel control panel. It is used to determine whether the aircraft ground attitude is within the limits necessary to achieve the required degree of accuracy for –
1. Use of the MFLIs
2. High level fuel shut-off during refuelling.
The requirement is met when the bubble is within the nominal ground attitude envelope, indicated by a black line.
The indicator is horizontal when the bubble is in the E6 graticule, which corresponds to an aircraft attitude of 0 deg 55 min nose-up pitch and 0 deg roll. Each square of the grid represents ½ deg change in aircraft attitude and is identified alphabetically for roll attitude and numerically for pitch attitude.
LOAD LIMIT CONTROL
During the normal mode of fuel trim transfer, fuel is pumped either from tanks 9 and 10 into tanks 11, 5, and 7 to obtain a rearward CG shift, or from tank 11 into tanks 9, 5 and 7 to obtain a forward CG shift. The trim tank contents are pre-selected on two load limit selectors, one for tank 9 and 10 and the other for tank 11. Any fuel in excess of the trim tank requirements is transferred into tanks 5 and 7. The load limit control channels are duplicated and each one automatically continues controlling should the other channel fail.
FUEL QUANTITY INDICATION (FQI)
The FQI system measures the fuel contents of the tanks by means of capacitance type gauging channels, and provides individual indication of each tank content at the Flight Engineers fuel management panel or alternatively, at the refuel control panel for refueling.
THE NORMAL REFUELING OPERATION
NOTE: If the aircraft has arrived with a low fuel state and it is not possible to transfer sufficient fuel to tank 9, the nose landing gear weight switches may have operated, causing the overbalance protection circuit to operate and, therefore, the refuel valves of the rear tanks to remain shut when selected open. As the fuel weight increases in the forward tanks during refuelling, the nose Landing gear weight switches will operate, allowing the refuel valves of the rear tanks to open.
The refueling of the aircraft is carried out to schedules which specify the fuel distribution according to the total fuel load and specific gravity.
When refuelling, the fuel must be distributed in accordance with these instructions.
Refuelling with Passengers on Board
Passengers must not be on board the aircraft when it is being refuelled with fuel which does not contain Shell ASA-3.
This limitation does not apply when “topping-up” Tank 11 to achieve the required fuel load.
Minimum Fuel Load for GO-around/Baulked Landing
A Go-around or baulked landing must not be attempted unless the collector tank total contents are greater than 2,500kg. The total must be divided approximately equal between the four tanks.
A baulked landing with 2 engines inoperative must not be attempted if the fuel quantity in each collector tank supplying operating engines is less than 1,250kg.
The ground crew had to observe the following:-
The Fire Safety Precautions
The Electrical Safety Precautions
The Refuelling Safety Precautions
All persons, equipment and vehicles must be kept clear of the overflow/relief valve outlet beneath the rear fuselage. The equipment and vehicles also had to have sufficient clearance to allow for the aircraft sinking during the refuelling process.
If any fuel heater was inoperative, the fuel had to contain an approved icing inhibitor. The ground crew also had to observe the refuelling pressure limitation and in the event of Refuel Control Panel (RCP) caption warnings and/or fuel spillage, take the appropriate action.
The ground crew had to carry out the following preparation
(1) Make available electrical ground power
PRIOR TO OPENING REFUEL CONTROL PANEL ACCESS DOOR, ENSURE THAT THE SCAVENGE PUMP IS SWITCHED “OFF”. FAILURE TO DO THIS COULD RESULT IN FUEL SPILLAGE THROUGH THE OVERFLOW RELIEF VALVE.
(2) Open the refuel control panel access door and set the refuel master switch to “SET UP”.
(3) Check that the refuel control panel fuel quantity indicators (FQIs) register actual fuel contents.
If required, these values may be compared with those obtained from the fuel management panel indicators at the third crew member’s (3CPl) station prior to starting the refuelling procedure.
(4) At the refuel control panel, carry out the following checks:-
(a) Press and release the FILAMENT TEST switch and check that the five amber captions are illuminated and then extinguished.
(b) The green PRV caption should be illuminated continuously if the tank pressure relief valve (TPRV) system is serviceable. If it is not illuminated, check the filament by operating the FILAMENT TEST switch.
(c) Press the FQI TEST switch and check that the FQIs show the appropriate approximate increases
FQI INDICATOR INCREASE IN READING
Tanks 1, 2, 3, 4, 5A, 7A 200 kg each
Tanks 5, 6, 7, 8, 9, 10 500 kg each
Tank 11 3,000 kg
TOTAL FUEL 7,200 kg
FQI Test – Increase in Indicator Readings
(d) Release the switch and check that the indicators return to the original indication.
(e) With the TPRV selector switch at NORMAL, check that the green PRV caption is illuminated.
(f) Press and release the TPRV EARTH TEST switch and check that the caption is extinguished momentarily.
(g) Press the ORV TEST switch and check that its magnetic indicator displays diagonal stripes and then OPEN. Release the switch and check that the indicator displays diagonal stripes and then SHUT.
(5) Ascertain from the Refuelling Sheet the required fuel Load for each tank.
(6) Set the refuel panel controls for fuel loading as follows:-
(a) Tanks 1, 2, 3, 4, 5A and 7A
Set each refuel valve switch to “OPEN” and check that the associated magnetic indicators display yellow.
NOTE: There are no Load Limit selectors for these tanks. Fuel will enter each selected tank until the refuel valve is closed by a signal from the high Level sensor or its switch is set to SHUT. If the aircraft has arrived with a low fuel state and it is not possible to transfer sufficient fuel. To tank 9, the nose Landing gear weight switches may have operated, causing the overbalance protection circuit to operate and, therefore, the refuel valves of the rear tanks (Nos.2, 3, 6, 7, 5A, 7A and 11) to remain shut when selected open. As the fuel weight increases in the forward tanks during refuelling, the nose Landing gear weight switches will operate, allowing the refuel valves of the rear tanks to open.
(b) Tanks 5 and 6
Set the refuel valve switch (2) to “OPEN” for one or both of these tanks, as required; check that the valve magnetic indicators display yellow.
Set the tank selector switch to the tank to be partial loaded and pre-set the required Loading figure on the Load Limit selector
NOTE: If required, these tanks could be refuelled without using the Load limit selector, the procedure being as in operation 6a detailed above.
Tanks 7, 8, 9 and 10
For each pair of these tanks, proceed as in operation 6b as detailed above
Set the refuel valve switch to “OPEN” and check that the valve magnetic indicator displays yellow.
Set the tank selector switch to tank 11, and pre-set the required loading on the load limit selector.
(7) Press the REFUEL VALVE SHUT-OFF CHECK switch and check that all the refuel valve magnetic indicators displaying yellow, change to black. Release the switch and check that these indicators revert to yellow.
(8) Ensure that the aircraft and the refueller are earthed individually and bonded to one another
(1) Set the refuel master switch (15) to “REFUEL”.
Before SB 53-042A
(2) Open the refuel control unit (RCU) access doors. If required by local regulations, connect the fuel supply hose bonding leads to the bonding points on the doors.
NOTE: Normal bonding of the fuel supply hose to the aircraft is achieved by the metal-to-metal contact between the hose-end connectors and the aircraft couplings.
After SB 53-042A
Open the refuel control unit (RCLJ) access doors and ensure that the distance piece is latched by the spring clip. If required by local regulations, connect the fuel supply hose bonding leads to the bonding points on the doors.
NOTE: Normal bonding of the fuel supply hose to the aircraft is achieved by the metal-to metal contact between the hose-end connectors and the aircraft couplings.
Remove the blanking caps from the refuelling couplings and the hose ends and connect the hoses to the couplings.
(3) Remove the blanking caps from the refuelling couplings and the hose ends and connect the hoses to the couplings.
NOTE: If there is only one of the two refuelling hoses connected to an RCU, the other hose must either be disconnected or its hose-end pressure control unit shut off.
THE RCU HANDLE MUST BE TURNED TO “OPEN” OR “SHUT” BY STEADY DIRECT HAND PRESSURE ONLY. NO ATTEMPT MAY BE MADE TO HOLD THE HANDLE IN AN OPEN POSITION DURING REFUELING!
(4) Turn the RCU handles to “OPEN”. (If either RCU fails to open, return the handle of the serviceable RCU to “SHUT” and proceed as detailed in paragraph 5)
NOTE: It is not possible to open the RCU if refuelling pressure is being applied to the aircraft. If excessive resistance to opening is encountered, the possibility of pressure on the RCU due to Leaks in the hose-end controller shut-off device should be checked by disconnecting the hoses and then again attempting to open the RCU.
(5) Open the shut-off valve in each refueling hose end, and, if a hose-end pressure control unit is used, check that the control setting of the unit is correct.
(6) Commence refuelling and check that each selected tank fuel quantity indicator shows a progressive increase.
NOTE: Fuel will enter each selected tank until the refuel valve is closed by a signal from the high level sensor or the Load limit selector.
(7) When refuelling is competed, carry out the Refuelling Sheet Checking Procedure for correct fuel distribution
(8) Switch off the pressure from the refuelled and turn the RCU handles to “SHUT”.
NOTE: A dashpot prvents rapid movement of the handle. If difficulty is experienced in closing the RCU, open tank 11 refuel valve to relieve pressure and then close it.
(9) Set the refuel master switch to “OFF-DEFUEL”.
NOTE: The fuel quantity indicators will~ remain at the ‘end of refuelling’ state until the refuelling master switch is moved to SET-UP at the next refuelling procedure.
(10) Set the refuel valve switches to “SHUT”. Set the tank selector switches to “OFF”.
(11) Close the refuel control panel access door.
(12) Disconnect the fuel SUPPLY hoses and bonding leads. Refit the blanking caps to the refuelling couplings and hose ends.
Before SB 53-042A
(13) Close the RCU access doors.
After SB 53-042A
(13) Close the RCU access doors.
NOTE: It is not necessary to push up the door before closing, as the Link over centre locking system is replaced by a spring clip latch mechanism.
(14) Disconnect the aircraft and refueller earthling and bonding cables.
(1) Switch off and disconnect electrical ground power.
(2) Carry out checks for water contamination at the water drain valves.
(3) Set the right-hand RCU handle to the “SHUT” position; switch off the external power to the RCU and then disconnect the cable.
(4) Remove all external power cables.
Before SB 53-042A
(1) Disconnect the hoses and close the RCU access panels.
After SB 53-042A
(1) Disconnect the hoses and close the RCU access panels.
NOTE: It is not necessary to push up the access panels before closing, as the link over-centre locking system is replaced by a spring clip latch mechanism
(3) Close the refuel control panel access door. When convenient, drain residual fuel via the water drains, using the water drain tool.