8A-4101-00B-2

8A-4101-00B-2 in the left main landing gear

The 8A-4101-00B-2 is a hydropneumatic shock absorber installed on the left main landing gear of Mi-8, Mi-17, Mi-171 and Mi-172 helicopters. It is part of the main landing gear assembly and takes the loads that appear when the helicopter lands, taxis, brakes or moves over uneven ground. The shock absorber reduces the force transferred from the wheel and landing gear structure into the airframe. In service, this unit is not just a supporting strut. It is one of the key elements that protects the helicopter structure from repeated impact and vibration loads.

Landing load absorption by 8A-4101-00B-2

When the helicopter touches down, the left main gear receives a strong vertical load. The 8A-4101-00B-2 absorbs this load through controlled movement of the rod inside the cylinder. Hydraulic fluid passes through calibrated passages and valve elements, slowing the movement and dissipating part of the energy. The nitrogen chamber works as an elastic element and helps the shock absorber return to its working position without a sharp rebound. This gives the landing gear a smoother response and reduces peak loads on the fuselage attachment points.

Left-side installation of 8A-4101-00B-2

The final index “-2” in the designation 8A-4101-00B-2 identifies the left-side shock absorber. The matching right-side unit is 8A-4101-00B-1. This difference must be respected when ordering, repairing or replacing the part. The right and left shock absorbers perform the same general function, but they are not always interchangeable because installation fittings and layout may be mirrored. A request for “main landing gear shock absorber” is therefore not enough. The side of installation and the full part number should always be stated clearly.

Hydropneumatic operation of 8A-4101-00B-2

The 8A-4101-00B-2 uses AMG-10 hydraulic fluid and technical nitrogen. During compression, the rod moves into the cylinder, the fluid is forced through internal restrictions, and the nitrogen volume is compressed. This absorbs the landing impact and prevents the load from being transmitted too sharply into the structure. During rebound, the fluid moves back through the return damping path, which prevents the landing gear from extending too abruptly. This two-way damping is important not only during touchdown, but also during taxiing, braking and movement over rough surfaces.

Construction of the 8A-4101-00B-2 shock absorber

The shock absorber consists of a cylinder, rod, bushings, valve elements and sealing parts. Inside the assembly, piston and guide bushings keep the rod aligned, while valve components control the hydraulic flow during compression and rebound. Seals, cuffs, piston rings and sealing rings keep the working fluid inside and maintain pressure stability. During overhaul, the most important inspection points are the rod surface, cylinder condition, bushings, valve group, seals and cleanliness of the hydraulic cavity. Leakage, scoring or corrosion can quickly change the damping behavior of the unit.

Ground operation role of 8A-4101-00B-2

The 8A-4101-00B-2 continues to work after landing, while the helicopter is moving on the ground. Taxiing over concrete joints, prepared soil, rough pads or uneven surfaces produces repeated loads in the landing gear. The shock absorber dampens these movements and helps reduce stress on the landing gear frame and fuselage fittings. If the unit has lost nitrogen pressure, has internal leakage or sticks during movement, the helicopter may sit incorrectly, react harshly to ground loads or show visible fluid leakage. These signs should be checked before further operation.

Supply and documentation for 8A-4101-00B-2

For supply, the full designation 8A-4101-00B-2 should be used together with the left-side installation note. It is also useful to specify the required condition: new, from storage, repaired, overhauled or serviceable with passport documentation. Since this unit has limits by landings, service life and storage period, documentation is not optional for aircraft use. Before installation, the shock absorber should be checked by passport, aircraft parts catalog, maintenance manual and actual landing gear configuration of the helicopter.

Product Type: Main landing gear hydropneumatic shock absorber
Designation: 8A-4101-00B-2
Alternative Designations: 8А-4101-00Б-2; 8A-4101-00B-2
Function: Absorption of landing impact loads and damping of dynamic forces
Application / Where Used: Helicopter main landing gear systems
System / Installation Area: Main landing gear, left side
Part of System / Included in Set: Main landing gear assembly
Side of Installation: Left side
Right-Side Equivalent: 8A-4101-00B-1 / 8А-4101-00Б-1
Compatible Aircraft / Equipment: Mi-8, Mi-17, Mi-171, Mi-172
Operating Principle: Hydropneumatic damping with hydraulic fluid and nitrogen charge
Working Medium: Hydraulic fluid AMG-10
Gas Charge: Technical nitrogen
Operating Pressure: 6.0 MPa / 60 kgf/cm²
Operating Stroke: 0–60 mm
Rod Extension on Parking Under Full Load: 115 mm, according to supplied technical description
Rod Diameter: 85 mm, according to supplied technical description
Operating Temperature Range: −60 to +60 °C
Main Internal Components: Cylinder, rod, piston and guide bushings, valve group, seals and sealing rings
Weight: 26.5 kg
Assigned Resource: 4000 landings
Inter-Repair Resource: 2600 landings
Assigned Service Life: 10 years
Storage Life: 2 years
Scope of Supply: Shock absorber assembly
Technical Documentation: Passport 8A-4101-00B PS

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.