8A-4201-00A

8A-4201-00A in the front landing gear of Mi-8 helicopters

The 8A-4201-00A is a lever-type shock strut used in the front landing gear assembly of Mi-8, Mi-17, Mi-171 and related Mil-designed helicopters. Its main job is to absorb landing impact loads and dampen movement while the helicopter is on the ground. During landing, taxiing, braking or movement over uneven surfaces, the front landing gear receives repeated dynamic loads. The 8A-4201-00A reduces these loads before they are transmitted into the helicopter structure, helping protect the airframe, attachment points and landing gear assembly from excessive stress.

Landing and ground-load damping by 8A-4201-00A

The front landing gear does not only work at the moment of touchdown. It continues to absorb loads while the helicopter moves across concrete, prepared ground, field landing sites or uneven airfield surfaces. The 8A-4201-00A helps smooth out these impacts by combining hydraulic resistance with gas compression. When the strut is loaded, hydraulic fluid moves through internal passages and the gas chamber compresses, taking part of the shock. When the load is released, the strut returns in a controlled way instead of rebounding sharply.

Lever-type design of the 8A-4201-00A strut

The 8A-4201-00A is built as a lever-type front shock strut. This layout is used where the landing gear must handle repeated ground loads and still keep the helicopter stable during movement. The lever arrangement helps the strut work effectively on uneven surfaces, including unprepared or semi-prepared landing areas. For Mi-8 family helicopters, this is important because these aircraft often operate not only from paved airfields, but also from field sites where the landing gear sees sharper and less predictable loads.

Hydraulic fluid and nitrogen charge in 8A-4201-00A

Inside the 8A-4201-00A, hydraulic fluid AMG-10 and technical nitrogen work together as the damping and elastic medium. The fluid controls movement and absorbs part of the energy through hydraulic resistance. The nitrogen charge acts as the spring element and helps the strut return after compression. The correct charge pressure is essential. If the gas pressure is low, the helicopter may sit incorrectly on the front gear or the strut may work too harshly. If the unit leaks, the damping quality and landing gear behavior can change quickly.

Main components of the 8A-4201-00A assembly

The front shock strut assembly includes several major structural and working parts: cylinder assembly, rod assembly, lever assembly, plunger, bracket, protective cover and sealing elements. The cylinder and rod form the main working pair, while the lever and bracket transmit loads through the landing gear geometry. Seals, bushings, piston rings and protective parts keep the hydraulic cavity sealed and protect the moving surfaces from contamination. During repair or overhaul, special attention is paid to the rod surface, bearing areas, sealing condition, lever joints and signs of corrosion or mechanical damage.

8A-4201-00A applicability on Mi-8 series helicopters

The 8A-4201-00A is used on Mi-8 series helicopters, including Mi-8P, Mi-8T, Mi-17, Mi-171, Mi-171E and Mi-172, depending on the specific landing gear configuration. It is installed as part of the front landing gear assembly, not as a separate universal shock absorber for any helicopter type. Before replacement, the unit must be checked against the aircraft parts catalog, maintenance documentation and actual configuration of the front landing gear. This matters because different modifications may have changes in landing gear layout, documentation, or approved component versions.

Supply, overhaul and documentation for 8A-4201-00A

The 8A-4201-00A is an aircraft technical item, so condition and documents matter as much as the physical part. On the aviation spare parts market, such units are usually supplied as new / first-category stock, from storage without operating time, or after overhaul by an approved repair facility. For installation, the product passport should confirm the part number, acceptance status, service life, repair history and remaining limits. If the strut is supplied after overhaul, the repair documentation and test records should be checked before the unit is accepted for aircraft use.

Product Type: Front landing gear lever-type shock strut
Designation: 8A-4201-00A
Alternative Designations: 8А-4201-00А; 8A-4201-00A
Function: Absorption of landing impact loads and damping of dynamic forces
Application / Where Used: Helicopter front landing gear systems
System / Installation Area: Front landing gear
Part of System / Included in Set: Front landing gear assembly
Compatible Aircraft / Equipment: Mi-8, Mi-8P, Mi-8T, Mi-17, Mi-171, Mi-171E, Mi-172
Construction Type: Lever-type hydropneumatic shock strut
Working Medium: Hydraulic fluid AMG-10
Charging Gas: Technical nitrogen
Charging Pressure: 3.2 ±0.1 MPa
Operating Temperature Range: −60 to +60 °C
Main Assembly Components: Cylinder assembly, rod assembly, lever assembly, plunger, bracket assembly, protective cover, seals, bushings and piston rings
Example Component References: 8A-4201-50, 8A-4201-35, 8A-4201-10, 8A-4201-180, 8A-4201-160, 8A-4201-150
Weight: Not more than 39.12 kg
Assigned Resource: 4000 landings
Assigned Service Life: 27 years
Scope of Supply: Shock strut assembly, operational spare parts kit
Typical Supply Condition: New / first category, from storage, or overhauled depending on availability and documentation
Technical Documentation: Product passport for 8A-4201-00A and aircraft maintenance documentation as applicable

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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.