Rotary-wing aircraft such as helicopters rely on flight controls and drivetrains that contain multiple grease-lubricated components including bearings, swashplates, and splines. Periodic relubrication of these components during established maintenance intervals is the primary method for replenishment of grease prior to degradation, to ensure reliable and safe operation of assets. A project was completed to develop techniques for sampling and analyzing grease from the drivetrain components of rotary- wing aircraft. The project was developed to evaluate the effectiveness of existing maintenance intervals, and to develop engineering data sets to propose interval adjustments. Such adjustments could be made to enhance safety and performance, while finding opportunities to reduce manpower and operational costs. This project incorporates new technologies including the use of sampling tools outlined in ASTM D7718, and new analysis methods that allow for small sample volume evaluation of component wear, as well as grease contamination, oxidation, and consistency changes. This paper will present the progress that has been made: 1) development of means to obtain representative samples from bearings, swashplates and splines; 2) data analysis methods that combine maintenance and operating histories with grease analysis results; and 3) findings that may lead to safer and more economical operation of critical assets.
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