A method and apparatus for monitoring a pneumatic system. A number of parameters are monitored using a monitoring device connected to the pneumatic system, an energy harvesting unit configured to generate electrical energy from a gas in the pneumatic system, and a controller. The monitoring device comprises a number of sensors configured to detect the number of parameters. The controller is in communication with the number of sensors and the energy harvesting unit and is configured to process measurements for the number of parameters detected by the number of sensors and control operation of the energy harvesting unit. The number of sensors and the controller are powered by the energy harvesting unit. The monitoring device is powered using the electrical energy generated by the energy harvesting unit.