NR-30KU-4

Fuel supply function of the NR-30KU-4 pump-regulator

The main task of the NR-30KU-4 is to deliver aviation kerosene under pressure to the engine fuel nozzles. The pumping section generates high-pressure fuel flow, while the regulating section meters the required amount of fuel. Fuel delivery changes according to throttle position, compressor pressure, rotor speed, flight altitude, airspeed and engine control laws. Correct operation of the NR-30KU-4 is critical during start, acceleration, cruise, takeoff and transient regimes, where the engine must receive fuel accurately without overtemperature, surge or rotor overspeed.

Multiplunger pumping unit in the NR-30KU-4

The NR-30KU-4 uses a rotary multiplunger pumping unit with a variable swash plate angle. This design allows the pump-regulator to create high fuel pressure and regulate delivery according to system demand. The working medium is aviation kerosene such as TS-1, T-1 or RT. Because the unit contains precision plunger and spool elements, fuel cleanliness and correct inlet pressure are essential. Contamination, air in the fuel line, poor filtration or unstable feed from the booster pump can affect metering accuracy and engine operation.

Automatic fuel metering laws of NR-30KU-4

The regulating section of the NR-30KU-4 operates through different fuel-metering laws depending on engine mode. During start and low-idle operation below approximately 84% high-pressure rotor speed, fuel delivery is controlled by the built-in starting fuel automatic unit according to compressor discharge pressure with correction for ambient pressure. At higher operating speeds, around 84–86% high-pressure rotor speed and above, fuel control transfers to the centrifugal high-pressure rotor speed regulator. This allows the engine to move from start scheduling to normal automatic speed regulation.

NR-30KU-4 compressor guide vane and bleed valve control

The NR-30KU-4 also supports engine compressor control functions. It supplies fuel pressure to the CNA-30K guide vane actuator, which turns compressor guide vanes according to the engine operating schedule. The pump-regulator also participates in hydraulic control of compressor bleed valves, helping protect the engine from surge during start and acceleration. These functions connect fuel metering with compressor airflow management, making the NR-30KU-4 a central unit of the D-30KU / D-30KP hydromechanical control system.

Associated fuel and control units of NR-30KU-4

On the low-pressure fuel side, the NR-30KU-4 works with the DTSN-44S-PZT centrifugal booster pump, which supplies fuel from the aircraft tanks at stable inlet pressure. It is also associated with the TsVS-30K centrifugal air separator with filter-signalizer, which removes air and filters fuel before it enters the high-pressure pumping section. On the electronic limiting side, the unit can interact with the IMT-3 temperature actuator and RT-12 type temperature regulator. If turbine gas temperature exceeds the limit, the actuator shifts the metering element inside the pump-regulator to reduce fuel delivery.

Mechanical drive and installation of NR-30KU-4

The NR-30KU-4 is mounted on the aircraft accessory gearbox located on the lower accessory reduction gearbox of the D-30KU / D-30KP / D-30KU-154 engine separation case. The unit is driven mechanically from the high-pressure rotor through a splined torsion shaft. It is connected to the cockpit throttle levers through mechanical linkage, including cables, bellcranks and rigid rods depending on aircraft installation. During installation, the drive interface, mounting flange, seals, control linkage and fuel connections must be checked carefully.

Supply, repair and inspection of NR-30KU-4

The NR-30KU-4 is an aviation fuel-control unit and should be supplied with documentation whenever possible. Available conditions may include new production, storage stock, repaired, overhauled or bench-tested serviceable units. Before installation, the unit should be inspected for housing condition, drive interface, fittings, seals, adjustment points, corrosion, leakage traces, preservation state and documentation. Bench testing is essential for this type of unit and should confirm fuel delivery, pressure, starting schedule, acceleration behavior, guide vane control, limiting functions and interaction with associated correction equipment.