NP-25-5

Hydraulic pressure generation by NP-25-5

The NP-25-5 operates at a working pressure of 25 MPa / 250 kgf/cm². Its nominal delivery is 17 L/min at a nominal shaft speed of 2200 rpm. The pump is designed to work with AMG-10 hydraulic fluid and supply pressure to aircraft hydraulic system lines. Since the pump is used in high-pressure circuits, its condition directly affects the operation of hydraulic actuators, control units and mechanisms connected to the system. Stable suction conditions and clean hydraulic fluid are essential for correct operation.

Plunger operating principle of NP-25-5

The NP-25-5 works through reciprocating movement of plungers. When a plunger moves in one direction, it creates low pressure in the cylinder cavity and opens the suction valve, allowing hydraulic fluid to enter. During the return stroke, the fluid is compressed and forced through the discharge valve into the high-pressure line. This operating principle allows the pump to create high pressure in a compact body. Wear of plungers, valves or sealing elements can quickly reduce pressure and delivery stability.

Installation of NP-25-5 on aircraft engines

In aircraft use, the NP-25-5 is mounted on the aircraft engine accessory gearbox. On Il-76 aircraft, it is associated with D-30KP engines used on Il-76M and Il-76MD modifications. The pump is installed by a mechanical drive connection and receives rotation from the engine accessory gearbox. During installation or replacement, the mounting flange, shaft direction, drive interface, sealing surfaces and hydraulic lines must be checked. The direction of rotation is especially important when selecting the correct version.

NP-25-5 in Il-76 hydraulic systems

The NP-25-5 is used as part of the onboard equipment of Il-76 heavy military transport aircraft. In this role, it supplies pressure to hydraulic system units and supports operation of aircraft hydraulic consumers. The exact consumers depend on the aircraft hydraulic system configuration, but such pumps are generally used to feed hydraulic actuators, control mechanisms and power circuits. For aircraft installation, the pump must be checked against the aircraft maintenance documentation, engine configuration and approved parts catalog.

NP-25-5 and NP-25-5L versions

The pump may appear in documentation and on nameplates as NP-25-5, NP25-5, NP-25-5L or NP25-5L. The “L” suffix usually indicates left-hand shaft rotation. This distinction matters because pumps with different rotation directions are not selected only by physical similarity. If the wrong rotation version is installed, the pump may not provide the required delivery or may be damaged. For procurement, the full designation and required shaft rotation should be confirmed before shipment.

Use of NP-25-5 in specialized ground equipment

Besides aviation, the NP-25-5 and especially the NP-25-5L version may be used in specialized ground machinery. It is found in hydraulic systems of drilling-crane machines and heavy special-purpose equipment, including installations based on Ural or KamAZ truck chassis. In these applications, the pump is valued for its high working pressure and compact design. For non-aircraft use, mounting, shaft rotation, working fluid, filtration and operating mode should still be verified before installation.

Supply and documentation for NP-25-5

For supply, the pump should be requested by its full designation: NP-25-5 / НП-25-5, or NP-25-5L / НП-25-5Л if the left-hand rotation version is required. For aircraft use, passport and aviation technical documentation are important. Before installation, the pump should be checked for pressure, delivery, suction condition, leakage, shaft seal condition, flange condition and drive compatibility. Units supplied from storage or after repair should be accepted only after documentation and performance checks.