FUELLING METHOD

Abstract

A fuelling method is described which comprises the steps of dispensing an initial quantity of fuel to a fuel tank, waiting for a predetermined settling period for the fuel dispensed to the fuel tank to homogenise and settle, after the predetermined settling period has elapsed, taking a fuel quantity reading using a fuel gauge associated with the fuel tank, calculating a differential volume of fuel between the fuel gauge reading and a desired final fuel quantity, and dispensing to the fuel tank a volume of fuel substantially equivalent to the differential volume using a dispensing apparatus including a fuel volume meter.

Claims

1. A fuelling method comprising the steps of: dispensing an initial quantity of fuel to a fuel tank; waiting for a predetermined settling period for the fuel dispensed to the fuel tank to homogenise and settle; after the predetermined settling period has elapsed, taking a fuel quantity reading using a fuel gauge associated with the fuel tank; calculating a differential volume of fuel between the fuel gauge reading and a desired final fuel quantity; dispensing to the fuel tank a volume of fuel substantially equivalent to the differential volume using a dispensing apparatus including a fuel volume meter; and notifying an officer associated with the apparatus of the total fuel quantity contained within the fuel tank, the fuel quantity comprising a combination of the fuel quantity read using the fuel gauge after dispensing the initial quantity of fuel and waiting for the settling period to elapse, and the differential volume measured using the fuel volume meter.

2. A method according to claim 1, wherein the step of calculating takes into account the density of the fuel being dispensed.

3. A method according to claim 2, wherein the dispensing apparatus includes a fuel density meter.

4. A method according to claim 1, and used in the fuelling of an aircraft.

5. A method according to claim 4, wherein, after dispensing of the differential volume, the pilot or other officer of the aircraft is advised of the fuel gauge readings taken after dispensing of the initial quantity of fuel and after waiting for the settling period to elapse, and the differential volume of fuel that has been dispensed in order to satisfy the pilot or other officer that the aircraft is carrying the desired total quantity of fuel.

6. A method according to claim 5, wherein the quantities of fuel are expressed in weight of fuel.

7. A method according to claim 4, wherein the step of calculating a differential volume of fuel takes into account changes in the quantity of fuel required to be dispensed to the aircraft.

8. A method according to claim 1, wherein the step of calculating includes applying an uplift to compensate for potential metering inaccuracies.

Description

[0018] The invention will further be described, by way of example, with reference to the accompanying drawings, in which:

[0019] FIG. 1, which is a diagram illustrating steps in a method in accordance with an embodiment of the invention; and

[0020] FIG. 2 is a diagram illustrating use of the invention.

[0021] Referring to the accompanying drawings, steps in a refuelling method for use in the refuelling of an aircraft are illustrated.

[0022] At step 10, a refuelling operator 12 receives instructions from a control station 14 to attend an aircraft 16 and to dispense a provisional quantity of fuel thereto. After acknowledging receipt of the instructions, the operator 12 attends the aircraft 16 and, at step 18, connects hoses or the like to the aircraft 16 so as to permit fuel to be dispensed from a fuel tanker 20 or other fuel store such a fuel hydrant or the like to a fuel tank of the aircraft 16. The operator 12 controls a dispensing apparatus 22 associated with the fuel tanker 20 to commence the dispensing of an initial quantity of fuel to the aircraft 16. The initial quantity of fuel will typically be less than or equal to the aforementioned provisional quantity.

[0023] Conveniently, the dispensing apparatus 22 includes a control operable to allow the operator 12 to input an amount of fuel to dispense, and the apparatus 22 then operates to dispense that quantity of fuel to the aircraft 16, stopping the dispensing of fuel when it is determined that the input initial quantity of fuel has been delivered. It preferably further includes backstop controls to prevent overfilling.

[0024] Once the initial quantity of fuel has been dispensed, as indicated at step 24, the operator 12 waits for a predetermined settling period for the fuel dispensed to the aircraft 16 to homogenise and settle in the aircraft's fuel tank. The duration of the settling period may be of the order of, say, 10 minutes. The settling period may be the same, irrespective of the type of aircraft to which fuel is being dispensed, thereby simplifying the fuelling procedure for the operator 12, standardising the procedure for all aircraft. Alternatively, different durations of settling period may be employed with different types of aircraft 16 to take into account characteristics specific to the aircraft that can impact upon how long it takes for the fuel to settle and homogenise. Regardless, the settling period is chosen to be sufficiently long that, after the settling period has elapsed, the fuel gauge or gauges of the aircraft 16 provide an accurate indication of the quantity of fuel present within the aircrafts fuel tank.

[0025] Aircraft fuel gauges typically work by computing from the output of a fuel height or depth sensor, information regarding the shape and characteristics of the fuel tank and information regarding the characteristics of the fuel, a value for the weight of fuel present in the tanks. These calculations rely upon a number of assumptions being applicable. By way of example, one of the fuel characteristics used in the calculation relates to the density of the fuel. A single density measurement is typically made and it is assumed that this measurement applies to all of the fuel present. However, often this is not the case. Accordingly, it is common for the calculated weight of fuel output by the flight deck fuel gauge readings to provide an inaccurate indication of the weight of fuel actually present.

[0026] In step 26, a reading of the quantity of fuel present in the aircraft fuel tank is taken using the aircrafts fuel gauges, and in step 28 the operator receives final fuel quantity information setting out how much fuel needs to be present in the aircraft 16 before it can be signed off as ready for departure. The final fuel quantity information may be supplied via the control station 14 and/or after discussion with the pilot or other officer responsible for the aircraft. At step 30, the operator calculates, using the final fuel quantity information and the readings from the aircraft fuel gauge, a differential volume of fuel that must be dispensed to the aircraft 16 in order to result in the aircraft 16 carrying the desired final fuel quantity.

[0027] As mentioned above, aircraft fuel gauge readings often provide an inaccurate indication of the quantity of fuel actually present. In order to allow for potential inaccuracies, primarily within the aircraft fuel gauges as mentioned before but also potentially within the operation of the dispensing apparatus 22, the calculation of the differential volume may incorporate an uplift to ensure that the final quantity of fuel present on the aircraft (composed of the initial quantity of fuel measured using the aircraft fuel gauges, and the differential quantity including any such uplift) is within acceptable tolerances.

[0028] The calculation of the differential volume preferably takes into account variations in fuel density. In this regard, the dispensing apparatus 22 conveniently includes a fuel density meter, the output of which is used in the calculation of the differential fuel volume. Alternatively, density measurements taken at other points may be used. By way of example, a fuel density measurement may be taken at the point at which the fuel tanker 20 is filled, the measurement being used in all fuel volume calculations until the tanker 20 is next refilled. It will be appreciated, however, that this represents just one of a wide range of possible points at which the fuel density reading may be made. Preferably, the calculation of the differential volume of fuel is undertaken by a handheld computer or the like using information input by the operator 12, or supplied thereto electronically.

[0029] Once the differential volume has been calculated, the dispensing apparatus 22 is set (at step 32) to dispense that volume of fuel to the aircraft 16, preferably stopping automatically once the differential volume has been dispensed.

[0030] It will be appreciated that upon completion of the dispensing of the differential volume of fuel, the aircraft will be carrying the desired final fuel quantity. The pilot or other officer responsible for the aircraft 16 can be provided with an updated indication of the quantity of fuel on board, comprising the initial quantity and the differential volume, for sign-off that the desired final quantity of fuel has been dispensed to the aircraft. As set out hereinbefore, the final quantity of fuel on board is derived from a combination of the fuel gauge readings taken after dispensing of the initial quantity (and after elapse of the settling period) in combination with information provided by the operator 12 of the differential quantity of fuel subsequently supplied. Whilst the dispensing apparatus 22 is configured to control the volume of fuel dispensed to the aircraft 16, the operator 12 instructing the apparatus 22 to dispense the calculated differential volume, and the apparatus 22 provides an indication of the volume of fuel dispensed in, for example, cubic meters or in another suitable volume measurement unit, the operator 12 is able to provide the pilot or other officer responsible for the aircraft with the corresponding, calculated weight of the differential volume dispensed for combination with the fuel weight readings output by the aircraft fuel gauges so that the pilot or officer responsible for the aircraft is able to satisfy himself that the correct, desired fuel quantity is present.

[0031] Once the pilot or other officer responsible for the aircraft 16 is satisfied that the desired final fuel quantity is present, and so signs off that fuelling is complete, the operator 12 can disconnect the fuel tanker 20 from the aircraft 16 ready for aircraft departure.

[0032] It will be appreciated that the method of the invention is advantageous in that the refuelling process can be shortened through avoiding the need to repeatedly wait for the settling period to elapse before taking each fuel reading, instead only including this step after dispensing of the initial quantity. Not only is the refuelling process shortened in length, and so the risk of departure delays is reduced, but also fuelling accuracy can be enhanced through avoiding situations where the step of waiting for the settling period to elapse is omitted in order to make time savings and through permitting the use of metering equipment of greater accuracy. Enhancing fuelling accuracy allows operating efficiencies to be made.

[0033] Where used on aircraft having more than one fuel tank, it will be appreciated that elements of the method will be repeated in relation to each tank to ensure that the fuel level of each tank, and of the aircraft overall, is sufficient.

[0034] Whilst the description hereinbefore relates to the refuelling of aircraft, it will be appreciated that a similar methodology may be used in the fuelling of other forms of vehicle and in other applications, allowing time savings to be made and efficiencies arrived at through achieving better fuelling accuracy to be made.

[0035] The description hereinbefore is of one embodiment of the invention. It will be appreciated that a wide range of modifications and alterations may be made thereto without departing from the scope of the invention as defined by the appended claims.