ECN-91S

ECN-91S in the aircraft fuel system

The ECN-91S is an aircraft electrically driven centrifugal fuel pump used for fuel transfer and fuel supply inside onboard fuel systems. Its main task is to move aviation fuel from aircraft tanks toward the engine feed system or between fuel tanks, depending on the fuel system layout. The pump is used on Mi-8, Mi-17, Mi-171, Mi-172 and related helicopter platforms, as well as on other aircraft with compatible fuel-system architecture. In operation, the ECN-91S supports steady fuel movement during both flight and ground operation.

Fuel transfer function of the ECN-91S pump

The ECN-91S provides the required fuel flow from tank sections to downstream fuel-system elements. It may be used for supplying fuel toward the engine feed line or for transfer between aircraft tanks, depending on the specific aircraft configuration. The pump creates a controlled pressure rise and maintains continuous flow of aviation kerosene through the system. It is not a high-pressure engine fuel pump. Its role is to move fuel inside the aircraft fuel system before it reaches the engine fuel-control equipment.

Installation of ECN-91S in the fuel tank system

The ECN-91S is installed in the aircraft fuel system, typically through a tank-mounted installation unit or flange arrangement. In helicopter applications, the design may allow the pump to be removed for maintenance without removing the external tank from the fuselage, where this installation scheme is provided. This is useful for line maintenance because the pump can be accessed through the mounting assembly. Before replacement, the exact installation version, mounting device and aircraft modification should be checked against the fuel system documentation.

Centrifugal pump design of ECN-91S

The ECN-91S is a centrifugal pump driven by a DC electric motor. The electric motor specified for this version is MP-100S-3S. The pump casing contains the centrifugal impeller, which creates fuel flow and pressure rise during operation. The unit is designed for continuous operation with aviation fuel over a wide temperature and altitude range. Since the pump works in a fuel environment, the condition of the casing, impeller, motor, connector and sealing surfaces is important for reliable operation.

Filtration and protection of ECN-91S

The installation assembly for the ECN-91S may include a built-in mesh filter. This filter protects the pump impeller and internal flow path from larger mechanical particles that may be present in the tank or fuel line. Clean fuel is important for stable pump performance. Contamination can reduce flow, increase load on the motor, damage the impeller or cause unstable pressure. During maintenance, the filter, inlet area and pump body should be checked for blockage, corrosion, mechanical damage and signs of fuel contamination.

Electrical operation of ECN-91S

The ECN-91S operates from the aircraft 27 V DC power system. The rated voltage is 27 V with a permitted tolerance of ±10%. The pump is designed for continuous operation and is driven by the MP-100S-3S DC motor. Electrical checks should include supply voltage, current consumption, connector condition, insulation, motor operation and actual hydraulic output. A pump may rotate electrically but still fail to provide the required flow or pressure if the impeller is worn, the inlet is blocked or the internal hydraulic section is damaged.

ECN-91S and related ECN-91 versions

The ECN-91S belongs to the same general family of aircraft centrifugal fuel pumps as ECN-91B, but the exact suffix must be respected. ECN-91S uses the MP-100S-3S electric motor and has its own operating parameters, installation details and documentation. It should not be selected only by visual similarity or general flow rate. For supply or replacement, the full designation ECN-91S, the aircraft type, required condition and manufacturer documentation should be confirmed before shipment.

Supply and documentation for ECN-91S

For aircraft use, the ECN-91S should be supplied with passport and technical documentation when available. The condition may be new, from storage, overhauled, repaired or serviceable after inspection, depending on availability. Before installation, the pump should be checked by flow rate, pressure rise, current consumption, motor operation, sealing condition and compatibility with the aircraft fuel system. If the pump is supplied as part of a mounting unit or with installation hardware, the dimensions and weight should be confirmed for the exact delivery configuration.

Product Type: Aircraft electrically driven centrifugal fuel pump
Designation: ECN-91S
Alternative Designations: ЭЦН-91С; ECN-91S
Function: Fuel transfer from aircraft tanks to the engine feed system or between fuel tanks
Application / Where Used: Aircraft and helicopter fuel systems
System / Installation Area: Aircraft fuel system; tank fuel transfer / supply circuit
Compatible Aircraft / Equipment: Mi-8, Mi-17, Mi-171, Mi-172 and other applicable aircraft depending on configuration
Pump Design: Centrifugal
Drive Type: Electric motor drive
Electric Motor Type: MP-100S-3S DC electric motor
Power Supply Type: Direct current
Rated Voltage: 27 V ±10% DC
Current Consumption: 8.5 A according to supplied reference data; final value should be checked by manufacturer documentation
Pump Flow Rate: 3.8 m³/h / 3800 L/h
Pressure Head: 3 m
Pressure Rise / Differential Pressure: Not less than 0.82 kgf/cm² according to supplied data
Alternative Pressure Reference: 0.3 kgf/cm² appears in secondary supplied description and should be verified by passport / test documentation
Rotational Speed: 4800 rpm
Operating Altitude Capability: Up to 17,000 m
Operating Mode: Continuous
Working Fluid: Aviation fuel / kerosene
Working Fluid Temperature Range: −55 to +50 °C
Ambient Temperature Range: −60 to +50 °C
Design Features: Pump casing with centrifugal impeller; possible built-in mesh filter in installation assembly
Installation Type: Installation in aircraft fuel system / fuel tank mounting assembly
Overall Dimensions: 300 × 112 × 148 mm according to supplied technical data
Alternative Compact Pump Body Reference: 225 mm length × Ø90 mm according to supplied secondary description
Weight: Not more than 5.25 kg according to supplied technical data
Alternative Pump Unit Weight Reference: 2.7 kg according to supplied secondary description
Condition: As applicable
Documentation: Manufacturer passport and technical documentation available upon request
Inspection / Testing: Flow rate check, pressure rise check, current consumption check, motor operation, connector, filter, housing and sealing inspection

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