NP25-9

NP25-9 as an aircraft hydraulic pump

The NP25-9 is an aircraft regulated piston / plunger hydraulic pump designed to supply working fluid under pressure to onboard hydraulic systems. It is used to power hydraulic actuators and other aircraft hydraulic consumers that require high-pressure fluid flow. The pump converts mechanical rotation of the drive shaft into hydraulic pressure and works as part of the aircraft hydraulic equipment set. In aviation use, it is installed on engine or APU accessory drive gearboxes, depending on aircraft configuration.

High-pressure function of the NP25-9 pump

The NP25-9 operates with a nominal working pressure of 25 MPa / 250 kgf/cm². It supplies AMG-10 hydraulic fluid to hydraulic circuits used for aircraft control, service systems and other powered mechanisms. The pump is designed for loaded operation in pressure cycles rather than unlimited continuous high-pressure delivery. Under load, it works in impulse mode with pressure in the 170–220 kgf/cm² range, while between activations it remains in standby at lower pressure. This operating pattern should be respected during testing and service.

Operating cycle of NP25-9

The NP25-9 is intended for short loaded operating periods. According to the supplied data, one loaded activation should not exceed 3 minutes. Between loaded cycles, the pump works in standby mode at 15–25 kgf/cm². This matters during bench testing and aircraft troubleshooting. If the pump is held under full load longer than allowed, temperature rise, seal stress and accelerated wear may occur. A correct test should check both loaded pressure response and standby pressure behavior.

Installation of NP25-9 on aircraft gearboxes

The NP25-9 is mounted directly on the aircraft engine accessory gearbox or on the auxiliary power unit drive gearbox, depending on the aircraft installation. The pump receives mechanical rotation through a splined shaft connection. Rotation direction is clockwise when viewed from the drive shaft side. During replacement, the mounting flange, drive splines, shaft seal, inlet and pressure lines, drain path and rotation direction should be checked carefully. Installing the wrong rotation version or using poor inlet conditions can damage the pump.

NP25-9 on Il-62M, Il-18 and Il-38 aircraft

The NP25-9 is used as part of onboard hydraulic equipment on Il-62M long-range passenger aircraft, Il-18 aircraft and Il-38 / Il-38SD maritime patrol aircraft. It may also be used in mobile ground hydraulic units and test installations for aircraft servicing. The exact installation point and hydraulic circuit must be checked by the aircraft maintenance documentation, because the same pump designation may appear in different aircraft hydraulic layouts.

Plunger operating principle of NP25-9

The NP25-9 works through reciprocating plunger movement. During suction, the plunger creates low pressure in the working chamber and draws AMG-10 hydraulic fluid from the inlet line. During discharge, the fluid is compressed and forced into the high-pressure line. This operating principle allows the pump to generate high pressure in a compact body. The condition of plungers, valves, seals and the shaft sealing area directly affects pressure stability, leakage and serviceability.

Working fluid and inlet conditions for NP25-9

The NP25-9 is designed for AMG-10 aviation hydraulic fluid. The pump requires absolute inlet pressure in the range of 200–600 mmHg. Stable suction conditions are important because insufficient inlet pressure can lead to cavitation, noise, unstable delivery and increased wear. The hydraulic fluid temperature range is −40 to +80 °C, with short-term operation up to +120 °C according to the supplied data. Clean fluid and correct filtration are essential for reliable pump operation.

Supply and documentation for NP25-9

For supply or replacement, the pump should be requested by its full designation: NP25-9 / НП25-9. It is also useful to specify the aircraft type, required condition, rotation direction and documentation. For aircraft installation, passport records, storage status, repair history and test results are important. Before installation, the pump should be checked for pressure output, standby pressure, leakage, shaft seal condition, drain leakage, inlet condition, drive interface and compliance with aircraft hydraulic system documentation.

Product Type: Regulated piston / plunger hydraulic pump
Designation: NP25-9
Alternative Designations: НП25-9; NP25-9; НП-25-9; NP-25-9
Function: Supply of working fluid under high pressure to aircraft hydraulic systems and actuators
Application / Where Used: Aircraft hydraulic systems; specialized ground hydraulic units and test equipment
System / Installation Area: Aircraft engine accessory gearbox or APU accessory drive gearbox, depending on configuration
Compatible Aircraft / Equipment: Il-62M, Il-18, Il-38, Il-38SD; mobile ground hydraulic units and test installations depending on application
Pump Type: Regulated piston / plunger high-pressure hydraulic pump
Working Fluid: AMG-10 aviation hydraulic oil, GOST 6794-75
Nominal Working Pressure: 25 MPa / 250 kgf/cm²
Loaded Operating Mode: Impulse mode at 170–220 kgf/cm²
Maximum Loaded Operation per Activation: Not more than 3 minutes
Standby Mode Pressure: 15–25 kgf/cm²
Shaft Speed: 2200 rpm
Direction of Rotation: Clockwise when viewed from drive shaft side
Inlet Pressure: 200–600 mmHg absolute
Hydraulic Fluid Temperature Range: −40 to +80 °C
Short-Term Fluid Temperature: Up to +120 °C
Ambient Temperature Range: −60 to +80 °C
Drain Leakage Through Shaft Seal: Not more than 0.5 cm³/h during operation
Drive Type: Mechanical drive through splined shaft
Dry Weight: 4.7 kg
Inspection / Testing: Working pressure check, standby pressure check, impulse operating cycle check, leakage and drain check, shaft seal and spline inspection

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Warranty
All products are covered by a standard 6-month warranty.
Extended warranty is available upon request and is agreed individually; it may affect the final product price.