[0062] The device 1 in accordance with the invention and represented diagrammatically in FIG. 1 is intended for monitoring a standard air data system 2 of an aircraft, in particular of a civil transport airplane, of which only a part of the fuselage 3 has been represented in this FIG. 1 for reasons of simplification of the drawing.

[0063] It is known that such an air data system 2 is intended for measuring air data making it possible to determine values of parameters such as the altitude, the speed, etc., of the aircraft. To do this, the air data system 2 comprises, in a known manner:

[0064] probes 4 which are mounted, in a feed-through manner, on the fuselage 3 of the aircraft and access the exterior;

[0065] pressure sensors 5 which are each connected by way of a tube 6 to a probe 4 . Generally, such a tube 6 which effects a pneumatic link is connected to the associated pressure sensor 5 by means of a pneumatic connector 7 which makes it possible to disconnect it and reconnect it easily and rapidly. Moreover, with each pressure sensor 5 is associated an analog/digital converter 8 ; and

[0066] a central unit 11 which is connected to the pressure sensors 5 by electrical links 12 , for example in the form of a communication bus complying with the “ARINC 429” standard.

[0067] It is however also conceivable to integrate the pressure sensors 5 into the central unit 11 .

[0068] Generally, a civil transport airplane comprises three air data systems 2 of this type, of which:

[0069] a first provides data which are displayed in the cockpit, for the attention of the pilot;

[0070] a second provides data which are also displayed in the cockpit, but for the attention of the co-pilot; and

[0071] a third is used as backup to cope if necessary with the failure of one of said first and second systems.

[0072] For obvious safety reasons, these three air data systems must be made and must operate in a manner which is completely independent of one another, since otherwise the failure of one would have repercussions on the measurements of the other systems.

[0073] An object of the device 1 in accordance with the invention is to detect any failure of a pressure sensor 5 of such an air data system 2 .

[0074] For this purpose, said device 1 comprises:

[0075] said central unit 11 which is such as specified hereinbelow; and

[0076] a means of display 13 which is connected by a link 14 to the central unit 11 and which is able to display, if appropriate, on at least one display device, in particular a standard display screen 15 , mounted in the cockpit of the aircraft, a failure cue relating to at least one of said pressure sensors 5 (therefore corresponding to a failure cue relating to said air data system 2 ).

[0077] According to the invention, said central unit 11 comprises, as represented in FIG. 2 :

[0078] data acquisition means 16 that are connected (links 12 ) to the two pressure sensors 5 of FIG. 1 and that carry out the acquisition of first and second pressure values relating to the measurements made by said two pressure sensors 5 respectively;

[0079] a means of calculation 17 that is connected by links 18 to said data acquisition means 16 and that calculates the deviation between said first and second pressure values;

[0080] a means of comparison 19 A that compares this deviation received via a link 20 with a recorded predetermined threshold value, for example 30 mbar; and

[0081] a means of selection 21 A that outputs (or otherwise) an order to display a failure cue (which order is transmitted to the display means 13 by the link 14 ), as a function of the result (received via a link 22 A) of this comparison. More precisely, it outputs a display order if said deviation is greater than said threshold value and it outputs no order in the converse case.

[0082] Thus, by virtue of the device 1 , any failure of a pressure sensor 5 of an air data system 2 can be rapidly and reliably detected, without calling upon information external to this air data system 2 , such as for example information output by other air data systems of the aircraft. This therefore makes it possible, should a plurality of air data systems be present on the aircraft, to guarantee the strict mutual independence of the various air data systems.

[0083] In a preferred implementation, the two (or at least two) pressure sensors 5 of the air data system 2 are mounted on either side of the longitudinal axis 23 of the fuselage 3 of the aircraft, as represented in FIG. 1 .

[0084] In a particular implementation, the device 1 moreover comprises, as represented in FIG. 2 :

[0085] a standard means 24 for measuring the speed of the aircraft relative to the air so as to obtain an air speed value; and

[0086] a means 25 which is connected by a link 26 to the means 24 for comparing the air speed value thus measured with a predetermined speed threshold, for example 25 m/s (around 50 knots).

[0087] In this case, the means of selection 21 A which is connected by a link 27 to the means 25 orders the displaying of a failure cue only if, in addition to the aforesaid conditions, said air speed value is greater than said speed threshold.

[0088] In another implementation, the device 1 comprises at least three pressure sensors 5 and the calculation unit 11 comprises as many (three, four, etc.) means of acquisition 16 ( FIG. 3 ) as there are pressure sensors 5 .

[0089] In this case:

[0090] the means of calculation 17 calculates all the possible deviations between the various pressure values taken pairwise;

[0091] the means of comparison 19 A compares all the deviations thus calculated with said threshold value; and

[0092] the means of selection 21 A orders a possible displaying of a failure cue, as a function of the various comparisons thus carried out.

[0093] More precisely, said means of selection 21 A orders the displaying of a failure cue:

[0094] in a first variant, if at least one of said deviations is greater than said threshold value; and

[0095] in a second variant, if all said deviations are greater than said threshold value.

[0096] The device 1 can also comprise a means of calculation 28 and a memory 29 that are connected (links 30 to 32 ) between a means of acquisition 16 and the means of comparison 19 B, as represented in FIG. 4 .

[0097] In this case, the device 1 can employ the following process:

[0098] B1) make pressure measurements with the aid of at least one pressure sensor 5 of the air data system 2 , on the aircraft which is on the ground and the cabin of which is not pressurized, so as to obtain a third pressure value;

[0099] B2) on the basis of this third pressure value, calculate a first altitude corresponding to the ground altitude;

[0100] B3) pressurize the cabin (cockpit and passenger cabin) of the aircraft;

[0101] B4) make the aircraft take off;

[0102] B5) at an instant t 0 corresponding to a predetermined time T after takeoff, make pressure measurements with the aid of said pressure sensor 5 so as to obtain a fourth pressure value;

[0103] B6) on the basis of this fourth pressure value, calculate a second altitude corresponding to the aircraft's altitude at said predetermined time T after takeoff (that is to say at said instant t 0 );

[0104] B7) calculate a third altitude corresponding to the aircraft's altitude with respect to the ground, from said first and second altitudes;

[0105] B8) compare said third altitude with a predetermined altitude threshold; and

[0106] B9) if said third altitude is less than said predetermined altitude threshold, order the displaying of a failure cue relating to said air data system 2 on the display device 15 .

[0107] Preferably, said altitude threshold is less than the altitude reached by the aircraft, at said predetermined time after takeoff, should there be a fault with an engine of the aircraft (which is, in this case, fitted with at least two engines).

[0108] By way of illustration, said predetermined time T after takeoff can be substantially equal to 30 seconds, and said altitude threshold can be substantially equal to 30 meters (around 100 feet).

[0109] The device 1 can also comprise standard means 33 for monitoring the engines of the aircraft. These means 33 are connected to the means of selection 21 B by a link 34 so as to inform it of any detection of a malfunction of at least one of the engines of the aircraft. In this case, when a failure of a pressure sensor 5 is discerned, the means of selection 21 B orders the displaying of a failure cue only if no malfunction of an engine is signaled at the same time by the means 33 .

[0110] It will be noted that the elements 19 B, 21 B and 22 B of FIG. 4 can correspond to the elements 19 A, 21 A and 22 A of FIGS. 2 and 3 . However, they may also be means separate from said central unit 11 .

[0111] The mode of implementation of FIG. 4 has the advantage of allowing the detection of the failure of two pressure sensors 5 of the same air data system 2 . For this purpose, it can comprise additional elements 16 , 28 and 29 , as is illustrated by broken lines.

[0112] According to the invention, at least one detector 35 which is able to detect a failed coupling between the corresponding pressure sensor 5 and the probe 4 which is associated with this pressure sensor 5 can also be provided on at least some of the pressure sensors 5 ( FIGS. 1 and 5 ).

[0113] In this case, the central unit 11 moreover comprises, as is represented in FIG. 5 :

[0114] data acquisition means 36 that are connected by links 37 to said detectors 35 and that carry out the acquisition on the ground, before takeoff, of information relating to the coupling, which originates from said detectors 35 ; and

[0115] a means of selection 21 C which is connected by links 38 to said data acquisition means 36 and which orders, if at least one of said detectors 35 signals a failed coupling, the displaying of a failure cue relating to the air data system 2 on said display device 15 .

[0116] In a preferred implementation, at least one of said detectors 35 is integrated into a pneumatic connector 7 intended to join a pneumatic tube 6 associated with a probe 4 to the corresponding pressure sensor 5 . A detector 35 can in particular be a switch actuated by the coupling of the connector 7 , a laser diode, etc.

[0117] Furthermore, the means of selection 21 C can represent the means of selection 21 A and/or the means of selection 21 B, or else be independent of them.