Method and device for detecting, on the ground, the obstruction of a pressure tap of a static pressure sensor of an aircraft

A method and device for detecting, on the ground, the obstruction of a pressure tap of a static pressure sensor of an aircraft. The device includes a pressure sensor that measures the pressure inside a probe and a heating system for heating the probe. When the heating system is activated, the sensor carries out a first measurement of a parameter dependent on the pressure inside the probe. After a predetermined duration from the activation of the heating system, the sensor carries out a second measurement of the parameter. A central processing unit calculates the difference between the first and second measurements and compares this difference to a predetermined value. A warning device emits a warning signal indicating the detection of an obstruction if the difference is greater than the predetermined value.

FIELD OF THE INVENTION

The present invention relates to a method and a device for detecting the obstruction of a pressure tap of at least one static pressure sensor of an aircraft, on the ground.

BACKGROUND OF THE RELATED ART

Usually, such a static pressure sensor is part of an anemometric unit which is intended to measure air data and so determine values of parameters such as the altitude of the aircraft, its speed, etc., which are in particular used to pilot the aircraft.

It is known that such a static pressure sensor normally comprises at least:a probe provided with a pressure tap passing through the fuselage of the aircraft;a module that is linked by a pipe to said probe; andan activatable heating system which is provided to heat said probe.

Any failure of such a static pressure sensor must of course be able to be detected quickly and reliably, since otherwise, the measurements taken will provide erroneous values for the abovementioned parameters (used for piloting), which can have very damaging consequences for the security of the aircraft when in flight.

It is known that human errors, in particular on airplane maintenance operations, can lead to the failure of such a static pressure sensor.

For example, the people responsible for washing the airplane often stick a piece of adhesive tape over the pressure tap of the probe, in order to prevent water from penetrating into the pipe linked to said probe during said washing. If the removal of the piece of adhesive tape after washing is forgotten, the pressure sensor will fail on the next flight of the aircraft, since it cannot measure the air pressure outside the fuselage. It will in fact measure the air pressure imprisoned in the pipe which is sealed (at its probe side end) by the piece of adhesive tape, this measured pressure obviously being different in flight from the outside pressure.

Various solutions are known (patent applications FR-2 847 669 and FR-2 857 447, for example) making it possible to detect the failure of a pressure sensor which is part of an anemometric unit of an aircraft. However, the known solutions only make it possible to detect a failure when the aircraft is flying. In the case of such a detection in flight, it is simply possible to stop taking into account during the rest of the flight the measurements taken by the failed pressure sensor, in order not to take account of false measurements (which is obviously important for safety), but repairing the failed pressure sensor is not possible. Although an anemometric unit of an aircraft normally comprises several pressure sensors so that the failure of one of said pressure sensors does not prevent the flight from continuing, the failure to take into account the data from a pressure sensor can, nevertheless, have a negative effect on the accuracy of the values of the parameters used to pilot the aircraft, which are derived from the measurements taken by this anemometric unit.

SUMMARY OF THE INVENTION

The object of the present invention is to remedy these drawbacks. It relates to a method for detecting, on the ground, quickly and reliably, and inexpensively, any obstruction of a pressure tap of a probe of at least one static pressure sensor of an aircraft, in particular of an airplane, said static pressure sensor being provided to measure the pressure inside the probe and comprising, in addition to said probe, at least one activatable heating system provided to heat the latter.

To this end, according to the invention, said method is noteworthy in that:a) on activation of the heating system of at least one static pressure sensor, a first measurement is taken using said static pressure sensor of at least one parameter dependent on the pressure inside said probe;b) a first predetermined duration after said activation of the heating system, a second measurement of said parameter is taken using said static pressure sensor;c) the difference between said first and second measurements is calculated;d) the duly calculated difference is compared with a predetermined value; ande) if this difference is greater than said predetermined value, a warning signal is emitted, indicating the detection of an obstruction.

The present invention therefore takes account of the fact that if the pressure tap of the probe is blocked or obstructed, for example by a piece of adhesive tape, the air imprisoned inside this probe will heat up immediately the heating system of the probe is activated such that the static pressure inside the probe that is measured by the static pressure sensor will then very quickly increase. This increase can be detected by directly monitoring the static pressure or by monitoring another parameter, in particular the barometric altitude or the barometric altitude rate, which depends on this static pressure.

Since usually the heating system of the probe is activated on the ground, normally immediately at least one engine of the aircraft is started up or when the aircraft begins to taxi or on activation of a general heating system, it is possible, thanks to the invention, to monitor the obstruction of a pressure tap of a static pressure probe when the aircraft is still on the ground. Thus, if such an obstruction is detected, the maintenance personnel can quickly unblock the obstructed probe before the aircraft takes off. The failed static pressure sensor is therefore rapidly returned to operation and can be used as early as the scheduled flight, unlike what happens for the abovementioned usual solutions.

Advantageously, there is also implemented monitoring of the state of activation of said heating system of the static pressure sensor and, in the step a) , said first measurement is taken immediately the activation of said heating system is detected thanks to said monitoring.

In a particular embodiment, in the step e) , a warning signal is emitted only if said difference is greater than said predetermined value for at least one second predetermined duration.

As indicated previously, said measured parameter can represent the barometric altitude. In this case, preferably, two static pressure sensors are used and each of said first and second measurements of the barometric altitude is taken using air data supplied by these two static pressure sensors.

Said measured parameter can also represent the barometric altitude rate.

obviously, in a simplified variant, said parameter simply represents the static pressure that is present inside the probe and that is measured by the static pressure sensor.

The present invention also relates to a device for detecting on the ground the obstruction of a pressure tap of a probe of at least one static pressure sensor of an aircraft, said static pressure sensor being provided to measure the pressure inside said probe and comprising, in addition to said probe, at least one activatable heating system provided to heat the latter. According to the invention, said device comprises:at least said static pressure sensor to take:on activation of the heating system of said static pressure sensor, a first measurement of at least one parameter dependent on the pressure inside said probe; anda first predetermined duration after said activation of the heating system, a second measurement of said parameter;at least one central processor unit to calculate the difference between said first and second measurements and compare the duly calculated difference with a predetermined value; andwarning means to emit a warning signal indicating the detection of an obstruction, if said difference is greater than said predetermined value.

Said device makes it possible to provide effective and robust monitoring of at least one static pressure sensor of an aircraft.

In a preferred embodiment, the device according to the invention also comprises at least one means for monitoring the state of activation of said heating system of the static pressure sensor.

Furthermore, said central processor unit can be part in particular:of a central alarm computer, of “FWC” (Flight Warning Computer) type; orof an inertial reference and anemometric data unit, of “ADIRU” (Air Data Inertial Reference Unit) type.

Moreover, in a particular embodiment, said warning means comprise a screen for displaying warning messages, of “ECAM” (Electronic Centralized Aircraft Monitoring) type.

DETAILED DESCRIPTION OF THE INVENTION

The device1according to the invention and diagrammatically represented inFIG. 1is intended to monitor at least one static pressure sensor2of an aircraft, in particular of a transport airplane, of which only a part of the fuselage3is shown in thisFIG. 1for reasons of drawing simplicity.

More specifically, said device1is intended to detect any obstruction of a pressure tap4A of a probe4of at least one static pressure sensor2of the aircraft.

It is known that such a static pressure sensor2is normally part of an anemometric unit10which is intended to measure air data, making it possible to determine parameter values such as the altitude, the speed, and so on of the aircraft. These parameters are in particular used to pilot the aircraft. Usually, a static pressure sensor2comprises:a probe4which is fitted transversally on the fuselage3of the aircraft and accesses the outside via a pressure tap4A;a module5which is linked by a pipe6to the probe4. Normally, the pipe6which provides a pneumatic link is connected to the module5by means of an pneumatic connector7which makes it possible to easily and quickly disconnect and reconnect it. Furthermore, an analog/digital converter8can be associated with said module5; anda usual heating system9, which is provided to heat said probe4and which can be actuated manually and/or automatically.

According to the invention, to detect a failure of the static pressure sensor2due to the fact that the pressure tap4A is obstructed (or blocked), said device1comprises:at least said monitored static pressure sensor2.This static pressure sensor2is formed to take:immediately said heating system9is activated, a first measurement of at least one parameter specified below, which depends on the pressure inside said probe4; anda first predetermined duration after this activation of the heating system9, a second measurement of said same parameter;at least one central processor unit11which is linked by a link12to said module5, to calculate the difference between said first and second measurements and compare this difference to a predetermined value specified below; andwarning means13which are linked by a link14to said central processor unit11, to emit a warning signal (visual and/or audible) indicating the detection of an obstruction, if the central processor unit11indicates to the warning means that the abovementioned difference is greater than said predetermined value.

In a particular embodiment, said warning means13emit a warning signal only if said difference is greater than said predetermined value for at least one second predetermined duration, also specified below.

The device1according to the invention therefore takes into account the fact that, if the pressure tap4A of the probe4is blocked or obstructed, for example by a piece of adhesive tape, the air that is imprisoned inside this probe4(and the pipe6) will heat up immediately the heating system9of the probe4is activated so that the static pressure inside the probe4(and the pipe6) which is measured by the static pressure sensor2will then increase very rapidly and significantly. This increase can be detected by the device1, either by directly monitoring the measured static pressure, or by monitoring another parameter (in particular the barometric altitude) which depends on this static pressure and varies abnormally when the latter varies abnormally.

Since usually the heating system9of the probe4is activated on the ground, normally immediately at least one engine (not shown) of the aircraft is started or when the aircraft begins to taxi or when the crew engages the probe heating pushbutton (“probe/windows heat pushbutton”), the device1is able to measure the obstruction of the pressure tap4A of this probe4, when the aircraft is still on the ground. Thus, if such an obstruction is detected on the ground, the maintenance personnel can quickly unblock the obstructed probe4, and this before the aircraft takes off. The failed static pressure sensor2is therefore rapidly repaired and returned to normal operation, and it can be used as early as the scheduled flight.

In a preferred embodiment, the device1according to the invention also comprises a means16for monitoring the state of activation of said heating system9of the monitored static pressure sensor2. This means16informs the device1immediately it detects the activation of said heating system9such that the device1can then take the abovementioned necessary measures. For this, said means16can in particular monitor the starting up of a first engine of the aircraft and/or the activation of a general heating system and/or the start of taxiing of the aircraft.

Obviously, the device1according to the invention can simultaneously monitor several static pressure sensors2.

It is known that, normally, an anemometric unit10of an aircraft is linked to at least two static pressure sensors2, the pressure taps4A of which are fitted either side of the longitudinal axis17of the fuselage3of the aircraft, as shown inFIG. 1.

It will also be noted that a civilian transport airplane normally has three anemometric units10of this type, of which:a first supplies data that is displayed in the Cockpit, for the attention of the pilot;a second supplies data that is displayed in the Cockpit, for the attention of the co-pilot; anda third is used as backup to safeguard, if necessary, against the failure of said first and second anemometric units10.

The device1can monitor all the static pressure sensors2of one anemometric unit10or all the static pressure sensors2of all the anemometric units10of the aircraft. For this, each time it comprises the static pressure sensors2that it monitors.

It will be noted that the link12used to link a module5to the central processor unit11is an electrical link, preferably implemented in the form of a communication bus to the “ARINC429” standard. The integration of different modules5directly in the central processor unit11could also be envisaged.

FIG. 2shows an exemplary assembly of a probe4on the fuselage3of an aircraft. For this, this assembly usually comprises, between said pipe6and the fuselage3, the following elements in turn:a screw coupling18;a washer19;the heating system9which is preferably of electrical type;a washer20;the static pressure probe4; anda washer21,
the elements9,4and21possibly being fixed by common bolts to the fuselage3, as illustrated by the chain dotted lines22.

Furthermore, said central processor unit11can be part in particular:of a central alarm computer, of “FWC” (Flight Warning Computer) type; orof an inertial reference and anemometric data unit, of “ADIRU” (Air Data Inertial Reference Unit) type.

Moreover, in a particular embodiment, said warning means13comprise a screen15, in particular a screen for displaying warning messages, of “ECAM” (Electronic Centralized Aircraft Monitoring) type.

In a first embodiment, the parameter measured by the device1represents the barometric altitude of the aircraft. The purpose of the device1is then to detect any significant and sudden barometric altitude variation, on activation of the (or each) heating system9of the (or each) monitored static pressure sensor2. In this case, preferably, the device1monitors and includes two static pressure sensors2, and each of the first and second measurements of the barometric altitude is taken using air data supplied by each of these two static pressure sensors2. The barometric altitude is then calculated each time, in the usual manner, from the static pressure averaged from the static pressure measurements taken by these two static pressure sensors2which are preferably located on the right and left sides of the aircraft.

Furthermore, in this first embodiment, it is possible to use, as an example, the following predetermined values:as first predetermined duration: 60 seconds;as predetermined barometric altitude value, with which the barometric altitude difference between the first and second measurements is compared: 20 feet (approximately 6 meters); andas second predetermined duration: 5 seconds.

Also, in a second embodiment, the parameter measured by the device1represents the barometric altitude rate.

Moreover, in a third simplified embodiment, the device1uses, as monitored parameter, the static pressure which is directly measured by the (or each) monitored static pressure sensor2, that is, the static pressure that exists inside the probe4and the pipe6of each monitored static pressure sensor2.

In this third embodiment, it is possible to use, as an example, the following predetermined values:as first predetermined duration: 75 seconds;as predetermined static pressure value, with which the difference between the first and second static pressure measurements is compared: 1 mbar; andas second predetermined duration: 10 seconds.

The device1according to the invention therefore makes it possible to provide an effective and robust monitoring of at least one static pressure sensor2of an aircraft.