NP92A-5

Hydraulic pressure generation by the NP92A-5 pump

The main function of the NP92A-5 is to supply working fluid under pressure to helicopter hydraulic consumers. The pump provides hydraulic power for control and service systems where stable pressure is required during flight and ground operation. Since the pump is driven from the main gearbox, it can continue supplying hydraulic pressure while the rotor transmission is rotating, including autorotation conditions if this is provided by the helicopter system design.

Variable delivery control of NP92A-5

The NP92A-5 is a variable-delivery pump. It changes output according to hydraulic system demand and pressure conditions. When hydraulic consumers require flow, the pump supplies fluid into the pressure line. When pressure reaches the regulated level, delivery is reduced to avoid unnecessary load, overheating and excess circulation of AMG-10 hydraulic oil. This automatic regulation is important for helicopter systems where hydraulic load changes during control input, landing gear operation, braking, or other actuator movement.

Axial plunger design of the NP92A-5

The NP92A-5 is built as an axial plunger pump with a rotating cylinder block. This construction is used in aviation systems where compact size, stable pressure and reliable high-speed operation are required. The plunger group generates pressure by repeated displacement of hydraulic fluid inside precision working chambers. For this reason, the pump is sensitive to fluid cleanliness, correct inlet conditions and proper hydraulic tank pressurization. Contamination, air in the suction line or insufficient anti-cavitation pressure may lead to noise, heating and accelerated wear.

NP92A-5 installation on the main gearbox

The NP92A-5 is driven mechanically from the accessory drive section of the helicopter main gearbox. Depending on helicopter type, the pump is mounted on the gearbox flange and connected to the hydraulic system through suction, pressure and drain lines. The drive interface, mounting flange, seals, shaft condition and port cleanliness must be checked before installation. Since the pump is installed on the main reducer drive system, correct mounting is important for both hydraulic performance and mechanical reliability.

NP92A-5 on Mi-26 and Ka-family helicopters

The NP92A-5 is used in hydraulic systems of heavy and multi-purpose helicopters, including Mi-26 and Ka-family helicopters such as Ka-27, depending on configuration and documentation. On these platforms, the pump may feed main and backup hydraulic systems and work together with the helicopter’s hydraulic tanks, filters, accumulators, control valves and actuators. The exact installation, pressure settings and gearbox interface must always be verified by the helicopter parts catalog and maintenance documentation.

Working fluid and anti-cavitation conditions for NP92A-5

The NP92A-5 operates with AMG-10 aviation hydraulic oil according to GOST 6794-75. The hydraulic system may use pressurized reservoir conditions to prevent cavitation at high pump speed and high demand. Air pressure for tank pressurization can be taken from engine compressor stages depending on helicopter design. Correct fluid temperature, cleanliness and inlet pressure are critical. If the pump is noisy, overheats or loses delivery, the inlet line, tank pressurization, filters and fluid condition should be checked together with the pump itself.

Supply and inspection of NP92A-5

For supply or replacement, the exact designation NP92A-5 should be stated. The pump may be supplied new, from storage, repaired, overhauled or bench-tested depending on availability. Before installation, the unit should be inspected for housing condition, drive shaft, flange surfaces, sealing areas, hydraulic ports, corrosion, leakage traces and preservation state. For aircraft use, bench testing is recommended to confirm pressure, delivery, regulation, leakage level and stable operation with AMG-10 hydraulic oil.