246-3904-000 Series 01

Yaw control function of the 246-3904-000 assembly

The 246-3904-000 assembly uses variable blade pitch to change the amount of lateral thrust generated by the tail rotor. When the pilot applies pedal input, the control system changes the pitch angle of the tail rotor blades through the hub and related control mechanism. This allows the helicopter to counter main rotor torque, maintain heading and perform controlled yaw movements. The tail rotor must respond smoothly across normal flight regimes, including hover, climb, cruise, descent and low-speed maneuvering. Any defect in the hub, blades, pitch mechanism or mounting interfaces can affect control response.

246-3904-000 Series 01 three-blade rotor design

The 246-3904-000 Series 01 is a three-blade, variable-pitch tail rotor assembly. This configuration combines a central hub with three tail rotor blades installed around it. The hub provides blade attachment, transmits control forces and supports blade pitch variation. The blades generate aerodynamic thrust when rotating in the airflow. The complete assembly must maintain correct geometry, balance and blade tracking to operate normally. During maintenance, the rotor should be considered as a complete system, because hub condition, blade condition and control movement are closely connected.

Assembly composition of 246-3904-000 Series 01

The 246-3904-000 assembly includes the tail rotor hub 246-3901-000 Series 01 as the primary load-bearing unit and three tail rotor blades 246-3925-000. The hub carries centrifugal, aerodynamic and control loads from the rotating blade set, while the blades generate the thrust required for anti-torque control. Compatibility between the hub, blade set and aircraft documentation is important. A tail rotor assembly should not be completed from visually similar parts unless the part numbers, series, logbook records and approved configuration match the target helicopter.

Application of 246-3904-000 on Mi-8 family helicopters

The 246-3904-000 Series 01 tail rotor assembly is used on Mi-8 family helicopters and derivative models. Typical applicability includes Mi-8, Mi-171, Mi-172, Mi-17-1V and Mi-171A2 helicopters, depending on the installed tail rotor system and aircraft documentation. The assembly may also appear in different civil and military configurations of the Mi-8 family. Since helicopters can differ by production year, modernization status, service bulletins and installed rotor components, applicability should be confirmed through the aircraft parts catalog, logbook and operational documentation before supply or installation.

Identification and service control of 246-3904-000 Series 01

Before ordering or installing 246-3904-000 Series 01, the complete assembly designation, hub designation, blade part numbers and logbook data should be checked. Service life, time to overhaul and accumulated operating hours are normally recorded in the individual component logbook. The logbook is especially important for assemblies with life limits, because the remaining resource depends on production year, operating conditions, overhaul history and recorded service time. For correct supply, it is useful to specify helicopter type, required condition, completeness, blade set, hub documentation and availability of operational records.