ECN-75B

Fuel transfer function of the ECN-75B pump

The main function of the ECN-75B is to move fuel from the main tanks to the service tank. The pump creates the required flow and low outlet pressure for continuous transfer through the aircraft fuel lines. It does not work as a high-pressure engine fuel pump. Its role is to support fuel movement inside the helicopter fuel system before fuel reaches the engine feed section. Correct operation of the ECN-75B is important because interruption of fuel transfer can affect fuel balance and the fuel reserve available in the service tank.

Tank installation of the ECN-75B on Mi-8 helicopters

On Mi-8 helicopters, one ECN-75B pump is typically installed in each external fuel tank. The left tank pump is installed in the forward part of the tank, while the right tank pump is installed in the rear part. The left and right pumps are controlled separately from the cockpit electrical panel. This separate control allows the crew or maintenance personnel to manage fuel transfer by tank side according to the aircraft fuel system logic. When ordering or replacing the pump, the installation position and aircraft modification should be checked against the maintenance documentation.

Monoblock design of the ECN-75B

The ECN-75B is built as a compact monoblock unit combining a centrifugal pump section and a DC electric motor. The drive motor is MP-50B. The pump rotates at high speed and delivers fuel through the outlet line at the specified flow rate. The design is simple and compact, which is important for tank installation where available space is limited. Since the pump is immersed in fuel, the working medium also participates in cooling and lubrication of the unit during operation.

Cooling and lubrication of ECN-75B by aviation fuel

The ECN-75B operates directly in aviation fuel, usually kerosene used in aircraft fuel systems. The fuel passing through the pump cools and lubricates internal elements during operation. For this reason, operation without fuel or with insufficient fuel level is undesirable and can lead to overheating, increased wear or pump damage. During maintenance, attention should be paid to pump cleanliness, fuel contamination, inlet condition, electrical insulation, connector condition and any signs of mechanical damage or corrosion after storage.

Electrical control of the ECN-75B

The ECN-75B is powered from the 27 V DC aircraft electrical system. The pump consumes a relatively low current and is switched from the onboard electrical control panel. In operation, the crew can control the left and right transfer pumps separately. Troubleshooting normally includes checking supply voltage, current consumption, switch operation, wiring continuity, connector condition and actual fuel delivery. A pump that runs electrically but does not produce the required flow should be checked for mechanical wear, contamination or internal blockage.

Supply and identification of the ECN-75B pump

For supply, the pump should be requested by its full designation: ECN-75B / ETSN-75B. The aircraft type, required condition and documentation should be confirmed before shipment. Since the unit is installed in the fuel system, external appearance alone is not enough to confirm serviceability. The pump should be checked for electrical performance, rotation, current draw, fuel delivery and outlet pressure according to the applicable aircraft maintenance documentation. For aircraft use, passport or acceptance documentation is recommended whenever available.