No abstract

The purpose of this paper is to present the research approach for the development of an algorithm for detection of a failure of the CH-53 swashplate bearing external spacer. The failure causes a lack of support of the swashplate bearing, thus creating a deformation of the outer ring. This study integrates the results of a new 3D dynamic model, developed for assessment of the defect pattern, and results from experiments. The research approach is planned in hierarchical phases. The experimental phases include a small scale specimen, full scale test rig, helicopter blades test facility and finally a CH-53 helicopter. The unique approach gradually simulates the real work environment of the swashplate bearing. The first two experimental phases and their results are presented. The first experimental phase is conducted on a small scale specimen and the second phase on a full scale test rig. Model results indicate that the lack of support has a defect pattern in both the radial and axial directions. These results are validated with the small scale specimen. In the future phases, the algorithm will be validated with data from the helicopter blades test facility and CH-53 helicopter.

No abstract

This paper presents a research of deformations influence on duplex ball bearings dynamic behavior. Despite the common use of duplex ball bearings, bearings subcomponents deformations are not thoroughly investigated. In order to investigate these effects, this study integrates the outcome of a 3D dynamic model, developed for assessment of the defect pattern and experimental results from a full scale CH-53 Swashplate test rig. The ability to withstand high radial and bi-directional axial loads makes duplex bearings common in aircraft applications and specifically in helicopter rotors. The swashplate of the CH-53 is constructed of duplex angular contact ball bearings. Two spacers, internal between the static inner rings and external, between the rotating outer rings support the bearing rings. A structural defect is formed by a faulty external spacer, thus causing a lack of support to the top bearing and deformation of the outer rings. Model results indicate that the lack of support has a defect pattern in both radial and axial directions. Test rig data acquired by accelerometers was analyzed by several diagnostic techniques including order tracking, envelope analysis and dephased algorithm in order to recognize the simulated pattern.