Tyre monitoring

An apparatus for health-monitoring an aircraft wheel comprising a pneumatic tire, the apparatus comprising:

• an internal tire pressure sensor;
• a tachometer configured to measure a rotational speed of the aircraft wheel;
• and
• a processor comprising an input configured to receive data from the internal tire pressure sensor and the tachometer;
• an output configured to send notifications related to a tire condition;
• and
• a machine-readable medium comprising instructions executable by the processor to cause the apparatus to:
• identify a minimum tire pressure following aircraft take-off, when the rotational speed is at, or close to, a maximum;
• identify a stationary tire pressure after said minimum, when the rotational speed indicates the wheel has stopped rotating;
• and
• derive a pressure difference, between the minimum tire pressure and stationary tire pressure, as a function of the rotational speed;
• and
• compare the pressure difference as a function of rotational speed over a plurality of take-off cycles to provide health monitoring of the tire.

An aircraft comprising:

• a pneumatic tire;
• at least one pressure sensor configured to measure an internal pressure within the pneumatic tire;
• at least one speed sensor configured to measure a rotational speed of the pneumatic tire;
• and
• a controller configured to receive data from the at least one pressure sensor and the at least one speed sensor, and output an indicator of a condition of the pneumatic tire, wherein the controller is configured to determine the output indicator by:
• tracking, using the data from the at least one pressure sensor, the internal pressure within the pneumatic pressure with respect to time during use of the pneumatic tire;
• identifying at least one change in the internal pressure during a time interval between a first reference time and a second reference time, the first and second reference times corresponding to points at which the at least one speed sensor indicates different rotational speeds of the pneumatic tire;
• and
• monitoring a pressure change of the internal pressure within the pneumatic tire as a function of rotational speed of pneumatic the tire to provide the indicator of the condition of the pneumatic tire.

A method of monitoring wear in a pneumatic tire, the method comprising:

• using a pressure sensor to measure an internal pressure within the tire;
• using a speed sensor to measure a rotational speed of the tire;
• monitoring the internal pressure with respect to time during use of the tire;
• identifying at least one change in internal tire pressure across a time interval in which the speed sensor indicates a change of the rotational speed;
• and
• monitoring the pressure change as a function of the rotational speed to provide an indicator of tire condition.