Method for monitoring a valve of an aircraft engine

1. A method for detecting first signs of failure in an aircraft engine valve, comprising:

acquiring of output pressure measurements of said valve and command and context data related to said valve,

defining of a set of indicators of first signs of failure as a function of said output pressure measurements and said command and context data,

monitoring a change over time of each indicator of said set of indicators of first signs of failure, and

detecting during said monitoring of a possible deviation of at least one indicator among said set of indicators, said deviation representing the first signs of failure of said valve.

2. The method according to claim 1 , wherein the detecting of a deviation of at least one indicator comprises:

determining for each indicator of a slope, called estimated slope, associated with the observed change over time of the indicator, and

detecting of a possible abnormal behavior of an estimated slope revealing a deviation of the indicator associated with said estimated slope.

3. The method according to claim 2 , wherein the detecting of an abnormal behavior of an estimated slope comprises at least one event among the following events: a break in slope, a slope above a first predetermined threshold value, and a slope below a second predetermined threshold value.

4. The method according to claim 2 , wherein the detecting of an abnormal behavior of an estimated slope comprises:

determining for each indicator of another slope, called expected slope, associated with a natural change over time of each indicator,

calculating for each indicator a guiding discrepancy, between the estimated slope and the corresponding expected slope, and

comparing of said guiding discrepancy related to each indicator with a corresponding predetermined warning threshold.

5. The method according to claim 4 , further comprising:

a learning phase to define the natural change over time of each indicator and to determine the expected slope related to each indicator from its natural change over time.

6. The method according to claim 1 , further comprising:

extrapolating of the observed change over time of each indicator up to a predetermined horizon of number of flights, and

calculating for each indicator a probability of exceeding a predetermined projected threshold by the value of the indicator at the horizon.

7. The method according to claim 1 , wherein the context data comprise ambient pressure data, valve supply pressure data and temperature measurements, and the command data comprise instants of command to open and to close said valve.

8. The method according to claim 7 , wherein said set of indicators of first signs of failure comprises one or more indicators among the following indicators:

a time delay to open said valve determined by the time delay between the instant of command to open the valve and the instant where the output pressure verifies a predetermined function indicative of an open valve,

a time delay to close said valve determined by the time delay between the instant of command to close the valve and the instant where the output pressure is around equal to the ambient pressure,

a state of opening of said valve determined by a comparison between the output pressure and said predetermined function indicative of an open valve, and

a state of closing of said valve determined by a comparison between the output pressure and the ambient pressure.

9. A system for detecting first signs of failure in an aircraft engine valve, comprising:

an acquisition device configured to acquire output pressure measurements of said valve and command and context data related to said valve, and

a processing device configured to define a set of indicators of first signs of failure as a function of said output pressure measurements and said command and context data, wherein

the processing device is configured to monitor a change over time of each indicator of said set of indicators of first signs of failure, and

the processing device is configured to detect a possible deviation of at least one indicator among said set of indicators, said deviation representing the first signs of failure of said valve.

10. An aircraft engine, comprising:

the system for detecting according to claim 9 .