Planetary Bearing Fault Diagnosis for a CH-46E Helicopter Main Gearbox

Abstract

Helicopters provide versatilities and conveniences in military, transportation, rescue and many other aspects. To ascertain a reliable, airworthy flight and reduce overall maintenance cost, condition monitoring techniques for helicopter main gearbox (MGB) has always been a key technology. Although current helicopter health and usage monitoring system (HUMS) is deployed on large size helicopters and proven to be effective, it still remains one of the most challenging tasks to detect and identify MGB defects occur on planetary bearings due to the structural and operational noise issues. This paper presents a study of diagnosing planetary bearing fault, utilizing valuable vibration data collected from a CH-46E helicopter main gearbox. The present study focuses on using frequency domain analysis techniques to detect defects in planetary bearings, and the techniques are tested on real-world data collected from a CH-46E helicopter aft MGB. Vibration data was examined in detail before being processed with techniques to mitigate the effects of variant rotational speed, suppress operational noise and enhance the signal-to-noise ratio of the faulty bearing signals. Results prominently reveal decisive indications of the defects for the faulty planetary bearing.