NP-92A-4

NP-92A-4 aircraft plunger hydraulic pump

NP-92A-4 is an aircraft plunger pump used in hydraulic systems of aircraft and helicopters. The unit belongs to aviation hydraulic equipment and is intended to generate high-pressure flow of working fluid for onboard hydraulic consumers. In the supplied context, NP-92A-4 is described as an axial-piston hydraulic pump with variable displacement, used in hydraulic systems installed on aircraft gearbox drive pads.

Function of NP-92A-4 in the hydraulic system

The main function of NP-92A-4 is to pump hydraulic fluid into the aircraft high-pressure hydraulic system. The pump supplies working pressure for hydraulic circuits that may include main, backup or auxiliary hydraulic systems, depending on aircraft type and configuration. The unit automatically adjusts its output according to system pressure, reducing flow when the hydraulic system reaches maximum operating pressure. This regulation helps limit unnecessary power consumption from the gearbox drive.

Application on helicopter gearbox drives

According to the supplied context, NP-92A-4 and related NP-92-series pumps are installed on accessory drive gearboxes of main helicopter gearboxes, including VR-24 on Mi-24 and VR-14 on Mi-8MT-type helicopters, depending on configuration and documentation. The pump is mechanically driven by a splined shaft connected to the gearbox drive. Exact applicability must be confirmed through the aircraft parts catalogue, gearbox documentation and hydraulic system maintenance manual.

Variable-displacement axial-piston design

NP-92A-4 is described as an axial-piston pump with adjustable output. In this type of pump, working fluid is displaced by pistons arranged along the pump axis. Flow regulation is achieved by changing the working displacement through a swash plate / cradle-type mechanism or by changing piston stroke through a pressure-responsive control mechanism. When system pressure rises to the upper operating limit, the pump transitions toward a low-flow or near-zero-flow mode.

Working fluid and pressure context

The pump is intended for aviation hydraulic fluid service. The supplied data specifies AMG-10 hydraulic oil according to GOST 6794-75 as the working medium. In the context of helicopter hydraulic systems of this class, the nominal operating pressure is stated as 21 MPa, with maximum pressure or valve adjustment level around 24–25 MPa. These values should be checked against the exact aircraft documentation and the individual pump passport before maintenance, installation or bench testing.

Identification and supply of NP-92A-4

When ordering NP-92A-4, the buyer should specify the complete designation, aircraft type, gearbox application and required condition. It is also important to confirm whether the requested item is a serviceable pump, overhauled pump, as-stored unit or pump for repair / exchange. Exact dimensions, mounting flange geometry, splined shaft data and flow characteristics at rated speed should be confirmed through the product passport, technical conditions and certified repair documentation.

Product Type: Aircraft plunger hydraulic pump / axial-piston variable-displacement pump
Designation: NP-92A-4
Alternative Designations: НП-92А-4, NP92A-4, НП92А-4
Related Modifications: NP-92A-5 / НП-92А-5 according to supplied context
Function: Generation of hydraulic pressure and flow for aircraft hydraulic systems
Application / Where Used: Main, backup or auxiliary aircraft hydraulic systems depending on aircraft configuration
Compatible Aircraft / Equipment: Mi-24 with VR-24 gearbox and Mi-8MT-type helicopters with VR-14 gearbox according to supplied context and documentation
Installation Area: Accessory drive pad of main gearbox / hydraulic drive unit area
Pump Type: Axial-piston plunger pump
Displacement Type: Variable displacement / adjustable output
Flow Regulation: Automatic reduction of pump output as system pressure approaches maximum working pressure
Drive Type: Mechanical drive from gearbox through splined shaft
Working Fluid: AMG-10 aviation hydraulic oil according to GOST 6794-75
Nominal Operating Pressure Context: 21 MPa / 210 kgf/cm²
Maximum Pressure / Valve Setting Context: Approximately 24–25 MPa / 240–250 kgf/cm²
Approximate Dimensions: Length 240–280 mm, body diameter / cross-section around 130–140 mm according to supplied context
Approximate Dry Weight: 8–10 kg according to supplied context
Technical Conditions Context: TU1-041-0053-1999 according to supplied context
Mounting: Flange-mounted pump installation on gearbox accessory drive, exact geometry according to technical documentation
Condition: New / As-Stored / Overhauled / Serviceable, depending on availability
Technical Documentation: Product passport, test report, serviceability certificate, overhaul records, aircraft maintenance documentation and bench test documentation if available

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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.