5349T Left

5349T left air-oil radiator in helicopter cooling systems

The 5349T is an aircraft air-oil radiator used in helicopter oil cooling systems. This version represents the left-side radiator unit within the overall paired cooling arrangement of Mi-8 family helicopters and related modifications. The radiator is designed to remove heat from lubricating oil circulating through the engine and main gearbox systems. During operation, it supports stable thermal conditions for assemblies that work under continuous mechanical load, including engine components, transmission elements, bearings, gears, and shafts. Correct operation of the 5349T helps maintain oil properties within the required range and reduces thermal stress on critical helicopter systems.

Oil cooling function of the 5349T radiator

The 5349T performs heat exchange between hot lubricating oil and ambient airflow passing through the radiator core. Oil from the aircraft system enters the radiator, transfers heat through the tube and collector structure, and returns to the lubrication circuit at a reduced temperature. This cooling process is necessary during different operating modes, including engine start, ground running, hover, climb, cruise flight, and operation in high ambient temperatures. The radiator must provide stable heat dissipation even when airflow and thermal load vary. Its condition directly affects the efficiency of the oil cooling system and the reliability of connected assemblies.

5349T dual-section construction for engine and gearbox oil

The 5349T is configured as a dual-section heat exchanger with independent oil circuits. One section is intended for engine oil cooling, while the second section is used for main gearbox oil cooling. This design allows one radiator unit to serve two separate lubrication systems without mixing their working fluids. The dual-section arrangement is especially important on Mi-8 type helicopters, where the oil cooling system must remain compact while supporting both the powerplant and transmission. Separate capacities, cooling surfaces, and tube groups are used for each circuit, allowing the radiator to operate according to the thermal requirements of each system.

Left-side installation of the 5349T radiator

The 5349T is supplied as the left radiator unit and operates as part of a left-right cooling system arrangement. Position matters because radiator connections, mounting points, ducting, airflow direction, and installation geometry may differ between sides. For replacement or procurement, it is important to confirm that the requested item is the left unit and not the opposite-side radiator or a related assembly. The part should be matched against the aircraft parts catalog and the actual configuration of the helicopter. This is especially important for helicopters that have undergone overhaul, modernization, or replacement of older radiator types.

System integration of 5349T with helicopter oil circuits

In the aircraft system, the 5349T radiator works together with oil pumps, oil lines, thermostatic elements, bypass circuits, and monitoring equipment. It may be associated with thermal regulation components that control oil routing depending on operating temperature. The radiator must maintain proper flow, withstand oil pressure, and preserve leak-tightness under vibration and temperature changes. Its internal passages must remain clean, while the outer core should allow free airflow for efficient cooling. Contamination, crushed fins, blocked passages, corrosion, or leakage can reduce cooling performance and create abnormal oil temperature conditions during helicopter operation.

Identification and interchangeability of 5349T / VMR 5349T

The radiator may be identified as 5349T or VMR 5349T. It is also referenced as an analog or interchangeable item for radiator 2281B / VMR 2281B, depending on aircraft documentation and configuration. This interchangeability should not be assumed only from the designation, because installation side, fittings, oil circuit layout, and approved documentation must be checked before use. When ordering, the required position, aircraft type, condition, documentation, and completeness should be specified clearly. For aviation supply, the radiator should be accompanied by a product passport and operational documentation confirming its status and applicability.

Product Type: Aircraft air-oil radiator / heat exchanger
Designation: 5349T
Alternative Designations: VMR 5349T, ВМР 5349Т
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, Mi-17, Mi-171, Mi-172 helicopters
Configuration: Dual-section radiator for engine oil and gearbox oil circuits
Position: Left radiator unit
Working Fluid: Lubricating oil
Cooling Surface, Engine Section: Approx. 2.76 m²
Cooling Surface, Gearbox Section: Approx. 1.84 m²
Number of Tubes, Engine Section: 12
Number of Tubes, Gearbox Section: 18
Maximum Oil Pressure at Inlet: Approx. 2 kgf/cm²
Thermostat Spring Setting Pressure: Approx. 2.5 kgf/cm²
Maximum Oil Temperature at Inlet: Up to +120 °C
Thermal Valve Activation Temperature: 65 ± 5 °C
Capacity, Engine Section: 2.2 ± 0.2 L
Capacity, Gearbox Section: 1.5 ± 0.2 L
Material: Aluminum collectors and core
Dimensions: Approx. 800 × 710 × 160 mm
Weight: Approx. 15.4 kg
Interchangeability: Analog / interchangeable reference for 2281B, VMR 2281B depending on aircraft documentation
Technical Documentation: Product passport and operational documentation

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