EPV-50BT Series 2

EPV-50BT Series 2 with the 1919T air damper

A typical application of the EPV-50BT Series 2 is operation together with the 1919T regulating air damper. This damper is used in hot-air lines, including anti-icing systems for engine air intakes on Mi-8 / Mi-171 family helicopters. In that installation, the actuator turns the damper to control the amount of hot air supplied to the required area. The result depends on the whole assembly: the actuator, the damper shaft, limit switches, wiring, and mechanical travel must all match the documentation. A serviceable actuator will not work correctly if the damper is stiff or if the end positions are set incorrectly.

Drive design of the EPV-50BT Series 2

Inside the EPV-50BT Series 2 are a DC collector motor, a multi-stage reduction gear, a microswitch panel, and a four-link lever mechanism. The motor provides rotation, the gearbox reduces speed and increases torque, and the lever mechanism transfers movement to the output shaft. The microswitches are used to control the end positions, so the actuator stops after reaching the required travel. This is important because the connected damper normally works between fixed limits and must not be driven past its mechanical stop.

Tropical execution of the EPV-50BT actuator

The letter “T” in EPV-50BT indicates tropical execution. This version is intended for aircraft operating in humid climates and in conditions where moisture, fungus, and temperature changes can affect equipment. The tropical version is dimensionally interchangeable with the basic EPV-50B by mounting interface, which is useful during replacement when the aircraft documentation allows it. The protection does not mean the unit can be ignored after storage: contacts, brushes, seals, gearbox movement, and external condition still need to be checked before installation.

Series 2 features of EPV-50BT

Series 2 is the later execution of the EPV-50BT actuator. It is used where improved reliability of the internal switching and drive mechanism is required under aircraft vibration and temperature changes. The operating logic remains familiar: power is supplied, the motor turns through the gearbox, the output shaft moves through its working angle, and the limit switches stop the mechanism at the end position. In maintenance, the most practical checks are full travel time, direction of rotation, end-position switching, shaft movement, and absence of abnormal noise or sticking.

Aircraft use of EPV-50BT Series 2

The EPV-50BT Series 2 is used on aircraft and helicopters where small rotary actuation is needed in air, heating, ventilation, conditioning, and anti-icing systems. On Mi-8 and Mi-171 family helicopters, it is commonly linked with the air-thermal anti-icing system and hot-air distribution to engine intake areas. The actuator may also be used with other dampers or valves if approved by the aircraft documentation. Before ordering, the exact designation, series, installation position, output shaft angle, and mating unit must be checked.

Inspection and supply of EPV-50BT Series 2

When ordering or replacing the EPV-50BT Series 2, it is better to specify not only the actuator designation, but also the series and required condition. The unit may be needed separately or as part of an assembly with a 1919T damper. Before installation, technicians normally check the body, connector, output shaft, gearbox smoothness, brush condition, microswitch operation, travel angle, and full operating time. For aircraft supply, the passport, storage condition, repair status, and compatibility with the required damper or valve should be confirmed.

Related system equipment: 1919T, EPV-150MT 2 series, SO-121VM ver. A. These positions are grouped by system function and installation context, not as interchangeable replacements.

Confirmed installation context includes Mi-8 / Mi-17 family helicopters. The exact execution and installation position must be checked against the illustrated parts catalogue and documentation for the specific aircraft.