2281B

2281B air-oil radiator in Mi-8 lubrication systems

The 2281B is an aircraft air-oil radiator used in the oil cooling system of Mi-8 family helicopters and related modifications. The unit is designed to remove excess heat from lubricating oil circulating through helicopter powerplant and transmission assemblies. During flight, the radiator works as part of the onboard thermal management system, helping maintain stable temperature conditions for components that operate under continuous load. Correct oil cooling is important for the service life of bearings, gears, shafts, and other assemblies that depend on stable lubrication properties.

Oil cooling function of the 2281B radiator

The 2281B performs heat exchange between hot lubricating oil and the airflow passing through the radiator core. Heated oil enters the radiator, transfers part of its heat through the tube and collector structure, and returns to the lubrication system at a lower temperature. This process helps keep oil viscosity and thermal condition within the required operating range. In helicopter operation, the radiator must provide reliable cooling during different modes, including climb, hover, cruise flight, hot-weather operation, and ground running where airflow conditions can vary significantly.

2281B dual-section construction for engine and gearbox oil

The 2281B is constructed as a dual-section air-oil radiator with separate cooling areas for different oil circuits. One section is used for engine oil cooling, while the other section is used for main gearbox oil cooling. This arrangement allows the radiator to support two important lubrication systems within one compact unit, while keeping their circuits independent. The dual-section design is especially practical for Mi-8 type helicopters, where available installation space is limited and the cooling system must serve several high-load assemblies without mixing the working oil circuits.

System integration of the 2281B on Mi-8 helicopters

In the helicopter system, the 2281B radiator is connected to the oil lines, mounting structure, and airflow path specified by the aircraft design. It operates together with the oil pumps, thermostatic and bypass elements where installed, and the airflow supply to the radiator area. The unit must provide stable heat transfer while withstanding vibration, pressure loads, oil temperature changes, and external environmental conditions. When replacing the radiator, correct installation and leak testing are important, because even small damage to the core or collectors can affect cooling efficiency and system reliability.

2281B and VMR 2281B identification

The product may be identified under the designations 2281B and VMR 2281B. In some supply and maintenance documentation, it may also be compared with the 5349T / VMR 5349T radiator as an interchangeable or analogous item for similar applications. Before procurement or installation, the required designation should be verified against the aircraft parts catalog, maintenance documentation, and the actual aircraft configuration. This is especially important when matching radiator fittings, mounting points, oil circuit layout, and allowed interchangeability between older and newer radiator versions.

Maintenance and supply considerations for 2281B

For aviation supply, the 2281B radiator should be checked by condition, documentation, completeness, and suitability for installation. The core and collectors must be inspected for mechanical damage, corrosion, contamination, deformation, and traces of previous leakage. Oil passages should be clean and suitable for the required system. Depending on the supply case, the item may be offered as new, serviceable, overhauled, or from storage. For installation on an aircraft, the radiator should be accompanied by the appropriate passport, acceptance documents, or operational documentation confirming its status.

Product Type: Aircraft air-oil radiator / heat exchanger
Alternative Designations: 2281B, VMR 2281B, ВМР 2281Б
Function: Cooling of engine and main gearbox lubrication oil
Application / Where Used: Helicopter oil cooling systems
System / Installation Area: Engine and main gearbox lubrication systems
Compatible Aircraft / Equipment: Mi-8 family helicopters and related modifications
Configuration: Dual-section radiator for engine oil and gearbox oil circuits
Cooling Principle: Heat exchange between lubricating oil and ambient airflow
Number of Tubes, Engine Section: 12
Number of Tubes, Gearbox Section: 18
Material: Aluminum alloy core and collectors
Destructive Pressure: Up to 10 kgf/cm²
Dimensions: Approx. 500 × 400 × 110 mm
Dry Weight: Approx. 13–15 kg
Weight with Oil: Increased by approx. 1.5–2 kg depending on oil volume
Interchangeability: Analog / interchangeable reference for 5349T, VMR 5349T depending on aircraft documentation
Technical Documentation: Product passport and operational documentation

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