NHBB has developed a wear sensor for the INVINSYS® brand of pitch link control bearings that enables helicopter maintenance personnel to easily and quickly determine the operating status of these flight-critical bearings using a wireless scanner. The added value created by NHBB’s patented wear sensor further establishes the INVINSYS brand as the leading bearing innovation within helicopter rotary systems.
Explicitly designed for rotor pitch control applications, INVINSYS bearing technology provides extremely low wear and lasts up to 2.5 times longer than preexisting products. The INVINSYS product with the embedded sensor provides the same performance as the sensor-less product – with the added benefits of bearing condition-signaling and part data storage. These added features support the shift to a condition-based maintenance plan for this critical bearing system, saving helicopter owners time and money in maintenance and repair activities.
This unique bearing monitoring system consists of a wear sensor embedded in the self-lubricating liner connected to a wireless transmitter mounted to the rod end body. The transmitter is a passive, ultra-high frequency (UHF) RFID tag (Class 1 Gen2) that can be read from a distance of six inches to three feet using a remote radio frequency receiver or scanner.
Designed and engineered per the requirements of SAE AS5678 (Passive RFID Tags Intended for Aircraft Use), the sensor's primary purpose is to accurately signal the current operating condition of the INVINSYS pitch link control bearing whenever a maintenance technician scans the tag.
A positive scan indicates the bearing is operating within the normal service life assigned to the bearing. A negative scan, or alarm signal, indicates the bearing has passed the service threshold and is now operating within the bearing’s reserve service life. At this stage, the bearing’s condition necessitates further inspection and possibly replacement during the next maintenance interval.
The sensor enables helicopter owners to extend maintenance intervals on these flight-critical parts, as it reduces the need to adhere to a rigid scheduled maintenance plan, which often leads to the replacement of suitable bearings on too short a timetable. With the sensor, maintenance techs need only to replace worn out parts. The longer-term impact on maintenance budgets could be significant.
The second task the wear sensor is capable of performing is that of part identification. The RFID tag meets the ATA Spec 2000 (Gen 2), the standard which details the asset tracking and management of products, parts, and property owned by the aerospace industry. The sensor's data format is compliant with the electronic product code (EPC), which allows maintenance techs to scan and download the product information stored on the tag.
The wear sensor is the development of the New Product Development Center (NPDC) in Laconia, NH. After conducting in-house testing on various prototypes, the NPDC is working closely with a customer to perform in-flight and field testing of the patented technology to validate the sensor's performance in actual flying conditions. Flight testing is scheduled for the Spring of 2016.
For more information about NHBB’s patented wear sensor technology, please contact the NHBB Astro Division.
