DTSN-70A

Fuel supply function of the DTSN-70A pump

The main role of the DTSN-70A is to maintain stable fuel flow and pressure before the fuel reaches precision engine fuel-control units. On TV3-117-type installations, fuel supplied from the helicopter tank system first enters the engine fuel path, then passes through the DTSN-70A and goes further to the fine fuel filter and pump-regulator. This helps ensure that the NR-3VM / NR-3VMA fuel pump-regulator receives fuel at the required pressure and flow rate for proper metering into the combustion chamber.

Installation of DTSN-70A on the engine gearbox

The DTSN-70A is installed directly on the engine accessory gearbox / drive gearbox. It does not have its own electric motor. Rotation is transmitted mechanically from the engine drive system, through the gearbox and pump shaft. This makes the pump directly dependent on engine rotation and accessory drive condition. During inspection or replacement, attention should be paid not only to the pump body, but also to the mounting face, drive connection, sealing surfaces, shaft condition and possible signs of leakage around the installation area.

Centrifugal operating principle of DTSN-70A

The DTSN-70A is a rotary centrifugal pump. Its rotor blades accelerate the fuel and create the flow required to move fuel through the engine supply line. The pump is compact, but works at high rotational speed and must maintain stable output across the engine operating range. The condition of the rotor, flow path, inlet line and seals directly affects pump performance. If the inlet pressure is unstable or the pump is worn, fuel delivery to the fuel-control system may become insufficient or inconsistent.

DTSN-70A and connected fuel system components

The DTSN-70A works in close connection with other engine and aircraft fuel-system components. Upstream, fuel is supplied by aircraft booster or transfer pumps such as ETSN-91B or 436B, depending on helicopter configuration. Downstream, fuel normally passes through the fine fuel filter, such as unit 8D2.996.236, and then reaches the NR-3VM / NR-3VMA pump-regulator. The pump-regulator raises pressure further and meters fuel to the combustion chamber. Because of this chain, faults in the DTSN-70A can affect the operation of the entire engine fuel-control system.

Drainage protection of the DTSN-70A pump

The DTSN-70A includes drainage cavities intended to prevent aviation fuel from entering the oil system of the engine accessory gearbox. Any fuel that passes through the sealing area is directed into the drainage path instead of mixing with the gearbox oil. This is important for safety and for maintaining oil quality. During maintenance, technicians should check the drainage cavity, drain connection and signs of leakage. Fuel traces at the drain may indicate seal wear or the need for further inspection before operation.

DTSN-70A in maintenance and fault inspection

During maintenance, the DTSN-70A should be checked by fuel delivery, inlet pressure, outlet pressure, leakage, drainage condition and mechanical drive condition. Since the pump is installed on the engine gearbox, any abnormal noise, fuel leakage, low output pressure or contamination in the downstream fine filter should be treated seriously. The pump is small and light, but it performs an important function in the engine fuel path. Its condition directly affects how reliably fuel reaches the pump-regulator.

Supply and documentation for DTSN-70A

For supply or replacement, the pump should be requested by its full designation: DTSN-70A / ДЦН-70А. The target engine type, aircraft application, condition and available documentation should be confirmed before shipment. Since the pump is an engine fuel-system component, external inspection alone is not enough. Compatibility with the engine gearbox, drive interface, fuel-system layout and maintenance documentation must be checked before installation. Passport or test documentation is recommended whenever the unit is intended for aircraft operation.