GA-59/1

GA-59/1 automatic valve in helicopter hydraulic systems

The GA-59/1 is an automatic hydraulic valve used in the main and standby hydraulic circuits of Mi-8 / Mi-17 family helicopters. Its function is tied to pressure loss in the main hydraulic system. Under normal pressure, the standby system remains unloaded and does not feed the hydraulic boosters. When pressure in the main system drops below the set level, the valve changes state and allows the standby hydraulic system to take over. This makes GA-59/1 one of the components that helps preserve flight control operation after a main system pressure failure.

Backup hydraulic engagement through GA-59/1

In operation, the GA-59/1 reacts to hydraulic pressure, not to a manual cockpit command. When the main system pressure is sufficient, the valve keeps the backup circuit in its normal standby condition. If pressure falls to the engagement range, the spring-loaded spool moves and separates the relevant internal ports. The standby hydraulic system then supplies the hydraulic boosters. When pressure is restored above the disengagement range, the valve returns the circuit to its previous condition. The exact behavior should be checked in the hydraulic system documentation for the aircraft.

Hydraulic circuit work with GA-59/1 installed

Inside the hydraulic system, GA-59/1 works with pumps, hydraulic tanks, pressure lines, return lines, check valves, hydraulic boosters, pressure switches, and related fittings. The valve does not generate pressure and does not repair a failed hydraulic line. It only switches the supply path when main system pressure is no longer sufficient. If the standby system fails to engage, the cause may be the valve, but it may also be low pump output, leakage, blocked lines, contaminated AMG-10 fluid, or a fault in another hydraulic component.

Mi-8 and Mi-17 application of valve GA-59/1

The GA-59/1 is used in helicopter hydraulic systems where the main and backup circuits jointly support the flight control hydraulic boosters. Open technical references link this valve with the Mi-8 hydraulic system, and equipment lists for Mi-171E identify it as an emergency power supply valve. Exact installation should still be checked by aircraft parts catalog and maintenance documentation, because Mi-8 / Mi-17 family helicopters can differ by modification, overhaul history, and hydraulic system layout. A visually similar valve should not be selected without checking the designation.

Identification and ordering checks for GA-59/1

Before ordering, the marking on the installed valve should be compared with the aircraft documentation. In English-language supply documents the unit is usually written as GA-59/1. In Russian documentation it appears as ГА-59/1. For a clear request, it is better to provide the helicopter type, system location, full part number, and a photo of the marking if available. The product is also known under alternative designation ГА-59/1.

Product Type: Automatic backup hydraulic system valve
Function: Automatic switching to backup hydraulic system upon pressure drop
Application / Where Used: Aircraft hydraulic systems
System / Installation Area: Main and standby hydraulic circuits
Compatible Aircraft / Equipment: Mi-8, Mi-17 helicopter family
Working Medium: AMG-10 hydraulic fluid
Backup System Engagement Pressure: 3.0 ± 0.5 MPa
Backup System Disengagement Pressure: 3.5 ± 0.5 MPa
Design Features: Spool valve with spring loading and built-in pressure damping throttle
Housing Material: Cast aluminum alloy
Internal Elements: Steel sleeve, spool, spring, throttle
Filtration: Mesh filter in fluid inlet fitting
Technical Documentation: GA-59/1 Technical Description and Operating Documentation

All shipments are carried out from our international warehouse in Dubai (UAE), as well as from our partners’ remote warehouses.

In Stock — items available in stock at the Dubai warehouse are dispatched within 5–10 business days after receiving 100% prepayment.

Remote Stock — items available at our partners’ remote warehouses are supplied within an average of 30–45 business days after receiving 100% prepayment.

Pre-Order — made-to-order products are manufactured and delivered within an average of 45–60 business days. Payment terms: 50% advance payment to start production, with the remaining 50% paid before dispatch from the Dubai warehouse after full readiness for shipment.

Returns & Changes (Restocking Fee)
For selected items, a RESTOCKING FEE of 10% may apply in case of return, order cancellation, or changes to the order specifications. This condition applies only to certain products and is confirmed at the order approval stage.

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.