MST-25A

MST-25A pressure switch for aircraft systems

MST-25A is a compact heat-resistant aircraft pressure switch used for monitoring gauge pressure in onboard hydraulic, fuel, oil and pneumatic-related systems. The unit is designed to close an electrical circuit when the pressure of the working medium rises to the preset value. It is used as a signalling device in aircraft and helicopter systems where reaching a defined pressure level must be transmitted to an indication, control or monitoring circuit.

Pressure signalling through MST-25A

The switch operates on pressure increase. When pressure in the connected line reaches the setpoint, the internal contact system closes the electrical circuit. This makes the unit suitable for applications where the monitored system must confirm pressure build-up or signal that a specified pressure threshold has been reached. The device does not provide continuous pressure indication like a gauge. It works as a discrete pressure relay with a fixed switching point.

MST-25A in hydraulic, fuel and oil systems

MST-25A can be used in aircraft hydraulic systems, fuel systems and oil systems, depending on the installation and compatibility of the working medium. The controlled media may include neutral gases and liquids, aviation oils, hydraulic fluids and gaseous oxygen. In helicopter applications, the unit is associated with systems installed on aircraft such as Mi-171E, depending on configuration. Exact applicability must be confirmed through the aircraft maintenance documentation or parts catalog.

Construction and operating features of MST-25A

The pressure switch is built for operation in high-temperature aircraft environments. The compact housing, pressure connection and internal contact mechanism allow installation in limited spaces where system pressure must be monitored locally. The heat-resistant version is designed for operation in areas exposed to elevated temperatures, vibration and operating loads typical of aircraft systems. The electrical contacts are rated for both resistive and inductive loads within the specified current limits.

Identification and ordering of MST-25A

Before ordering MST-25A, the full designation and switching logic should be checked. The letter “A” indicates operation on pressure increase, with contact closure when the set pressure is reached. Other MST versions may have different switching logic or setpoints. For correct selection, provide the aircraft type, system of installation, required pressure setting, working medium, electrical circuit parameters and a photo of the existing unit marking. The product is also known under alternative designations MST-25A and МСТ-25А.

Product Type: Aircraft pressure switch / pressure signalling device
Function: Closing of electrical circuit when working medium pressure rises to preset value
Application / Where Used: Aircraft and helicopter hydraulic, fuel and oil systems
System / Installation Area: Pressure monitoring circuits in onboard fluid and gas systems
Compatible Aircraft / Equipment: Mi-171E and other aircraft / helicopters, depending on configuration
Switching Logic: Contact closure on pressure increase
Index Meaning: “A” version operates on pressure rise
Nominal Switching Pressure: 25 kgf/cm²
Controlled Media: Neutral gases and liquids; aviation oils; hydraulic fluids; gaseous oxygen
Compatible Oils / Fluids: MS-8RK aviation oil; NGZh hydraulic fluid, depending on installation
Electrical Circuit Voltage: 27 V DC
Switched Current with Resistive Load: 1.5 A
Switched Current with Inductive Load: 0.5 A
Operating Temperature Range: −60 to +180 °C
Execution: Compact heat-resistant aircraft version
Approximate Weight: 0.18 kg
Service Life / Reliability: Technical life up to 30,000 h; service life up to 30 years
Alternative Designations: MST-25A; МСТ-25А
Technical Documentation: Product passport and aircraft system documentation available upon request

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.