U. S. Army Helicopter Rod End Bearing Reliability and Maintainability Investigation
SYSTEMS ASSOCIATES INC LONG BEACH CA
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The investigation was carried out to identify, isolate, and verify the causes of problems with rod end bearings REB used on U.S. Army helicopters and to trace the resulting effects on helicopter availability. Design requirements, quality assurance provisions, maintenance procedures and practices, test requirements, and procurement practices were analyzed to assess their impact upon the current problems. Excessive play between ball and race was found to be the REBs chief failure mode. Design does not adequately contend with a vibratory environment which tends to cause widening of the race. Quality assurance was neither imposed upon the bearing vendors nor demonstrated by airframe manufacturers. A recommendation was made for a specification to be developed to govern existing or new designs, which include a stainless steel ball with a ceramic coating and a graphite race, a slotted spherical bearing, and an elastomeric spherical bearing. The recommended specification for helicopter REBs includes bond and material integrity, loading, vibration, dust, misalignment angle, qualification and conformity requirements. Specific recommendations for improvements to the policies, practices, and procedures are made in the report hardware improvements are also discussed.
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