Bearings for Helicopter Gearboxes and Tail Rotors

The System That Prevents a Helicopter from Spinning on Itself

The tail rotor of a helicopter performs a function that often goes unnoticed: it counteracts the torque generated by the main rotor, preventing the fuselage from spinning uncontrollably around its own axis. RBC Bearings includes the complete tail rotor system within its helicopter applications portfolio, along with dedicated tail rotor linkage components. This system works in conjunction with the gearbox, which transmits engine power to both the main rotor and the tail rotor, as well as the actuator system that controls the blade pitch. RBC's helicopter portfolio also covers complete main rotor systems, engine systems, and landing gear systems. Among the specialized solutions documented by RBC for these applications are swashplate spherical bearings, damper bearings, pitch link bearings, lead-lag bushings, and scissor bearings, all qualified to the AS81819 standard with QPL approval. This standard requires resistance to water, fuels, oils, and solid contaminants. A helicopter remains stable in flight only because dozens of these components—from the main rotor to the tail rotor—operate in perfect synchronization. A single failure point in any one of these bearings can compromise the aircraft's overall flight stability. The same principle of synchronizing multiple power transmission points, although in a very different environment, is one that BIOSA addresses every day in industrial gearboxes and power transmission systems, where a single component outside of tolerance can affect the performance of the entire system. RBC also manufactures specialized fasteners for these systems, including the rotor hub bolt, the swashplate hex bolt, and the pawl-type pitch control rod bolt—small but critical components that hold the entire tail rotor and gearbox assembly together.