An Investigation of Legacy Vibration Checks on Modern H-47 Chinook Systems via Seeded Fault Testing

Vibration monitoring of dynamic components is an important part of ensuring aircraft safety and has been used to determine the health of rotating components since the inception of the modern day helicopter. Some vibration checks have not changed from the time that a specific helicopter was placed into service and others have been modified with the addition of Health and Usage Monitoring Systems (HUMS) with the goal to improve them. A seeded fault test on an MH-47 aircraft was conducted to directly compare modified vibration checks to the legacy checks, identify a method to decrease vibrations, and minimize maintenance. Data was collected using Modernized Signal Processing Unit (MSPU) which replaced the Aviation Vibration Analyzer (AVA) for rotor smoothing and all drivetrain vibration checks. While this paper will present lessons learned, it will also provide successful HUMS benefits. This paper will demonstrate that HUMS can not only maintain legacy vibration checks but improve them as well with changes that enhance airworthiness and reduce maintenance burden. This is an example of how HUMS continues to evolve as we press forward in the pursuit of providing aircraft users with the best tools possible.