Health and Usage Monitoring on the International CH-47D

A Health and Usage Monitoring System (HUMS) has been developed for the digital cockpit version of the International CH-47D and is currently being operated by the Royal Netherlands Air Force (RNLAF). The system architecture is unique in that the Air Vehicle signals are digitized for the pilots by dual Air Vehicle Integrated System Processors (AVISPs) which drive cockpit Multi-Function Displays (MFDs) for management of the air vehicle systems. Each AVISP sends many of the digitized signals to the HUMS computer, called a Modular Data Acquisition Unit (MDAU), via a dedicated ARINC 429 data bus. The MDAU reformats the data as required and sends it to a Combined Voice and Flight Data Recorder (CVFDR), as well as to a separate set of internal processing cards which calculate rotor track and balance, exceedance monitoring, usage monitoring, and transmission diagnostics (sensors for transmission diagnostics are not installed on the Digital International CH-47Ds at this time). Digitization of over 200 signals by the AVISPs greatly simplified the HUMS installation, however, unique integration and validation techniques had to be developed due to the signal conditioning, asynchronous sampling, and propagation delays associated with those signals, performed within the AVISPs, which were developed by a different supplier. Extensive rotor track and balance testing was performed to demonstrate the ability of the HUMS to accurately suggest recommended adjustments as required by routine maintenance as well as after major overhaul of the rotor system. Tests were conducted with single and multiple seeded faults on multiple aircraft. The HUMS successfully demonstrated the ability to correct the condition with data collected from a single flight on many occasions. Operational issues associated with record-keeping within a military organization which has an extensive computerized logistic system are being resolved in the field. A maturity plan is the mechanism being utilized to enable progressive utilization of data with the existing deployed system as well as specification and development of additional capabilities which are determined to be desirable.