Description:
Elastomeric thrust bearings on a RotorWay are the laminated rubber-and-metal “donut” style bearings in the rotor head (often called elastomeric bearings) that carry thrust loads and allow small amounts of controlled flexing so the blade grips can change pitch and “flap”/“lead-lag” slightly without using traditional rolling-element bearings that need grease. The elastomer (rubber-like compound) is bonded between metal plates; when the rotor pulls upward in flight or cyclic movement is introduced outside of center position, that stack is compressed and sheared, which both supports the rotor’s lift (thrust) and provides built-in damping, smoothing vibration and helping prevent shimmy and rapid oscillations in the head. When these bearings start to fail—usually from age, heat, UV-light exposure, chemical contamination or bond degradation—you’ll often see cracks, bulging/extrusion, delamination, or “cold flow” of the elastomer, and the helicopter may develop new or worsening 1-per-rev vibration, a roughness that changes with rotor RPM or collective, more noticeable stick shake, tracking that won’t stay consistent, or a “looser”/less-damped feel in the rotor system. It is not recommended to use grease anywhere near the elastomeric bearings as this can degrade the polymer prematurely. Some users have reported pulling of the cyclic that disappears after replacing elastomeric bearings, similar to cases that occur when the slider ball adjustment is too tight. In colder temperatures, it's common to feel a little more feedback than normal but it should not be excessive.

(New on the left, old on the right — Some minimal rubber polymer bulging is normal and not a concern if the rotor system is smooth)

 

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It's important to follow our maintenance manuals and inspect the elastomeric bearings every 100 hours or on every annual condition inspection. Taking the blades off at least annually will help to identify premature wear/remove any surface corrosion and allow for re-greasing of pitch pins and roller bearings. Wear clean gloves when handling elastomeric bearings to prevent oils from making contact with the polymer. Other helicopter designs with protective outer seals are more chemical resistant than our elastomerics.

Recommended Inspection Inverval: 100 hours (Section 13 of the Maintenance Manual)
Recommended Replacement Interval: 3 years (Section 24 of the Construction Manual)
Required Replacement Interval: 10 years or On Condition (Section 13 of the Maintenance Manual)
 

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