PRESS (Passive RFID Embedded Stress Sensor) system

Critical hardware located on Naval aviation helicopters undergo regular torque checks are performed based on number of days between maintenance cycles and flight hours. It is imperative this hardware is correctly torqued to provide the right preload necessary to a bolted joint, preventing unwanted vibrations, slipping, and further loosening of the hardware. The majority of the critical hardware most frequently checked is located in the rotor, engine, and driveline of the helicopter. Current methods for performing these torque checks involves using a torque wrench, however some hardware requires multiple other components to be removed to get the wrench in place increasing time to do the task, or required an extension and/or universal socket joint, which reduces the accuracy of the set torqued value. Both methods of completing the torque check process burns a significant amount of time and resources. In the Phase II effort of this project, Lynntech will further develop the PRESS (Passive RFID Embedded Stress Sensor) system. The PRESS system will be in the formfactor of a washer and will directly replace the washers which are currently used without the need to modify the current system. PRESS will have an embedded strain sensor that will detect the load applied by the bolt. The value measured by the strain sensor will then indicate the preload value experienced by the bolted joint. The preload valve can also be calculated into a torque value to ensure the hardware is within the original equipment manufacturer’s (OEM) specification. PRESS will have an integrated passive RFID tag which will communicate with an RFID reader when it is placed within range. The RFID reader will provide enough power for both the sensor portion and the RFID portion of PRESS. This will allow the user to determine the load the bolted joint is experiencing without having line of sight or needing to have physical contact with the bolt.