NP9

Fuel supply function of the NP9 pump

During start-up, the NP9 delivers aviation fuel from the supply line to the starting nozzle. This fuel is used for ignition and initial combustion in the AI-9 system. The pump must provide enough outlet pressure while receiving fuel at the required inlet pressure. If the pump output is weak, starting may become unstable, delayed or impossible. In maintenance, the NP9 should be checked together with the starting nozzle, fuel lines, filters and drive system, because similar start-up symptoms can come from several parts of the fuel-start circuit.

NP9 vane-type pump construction

The NP9 is a rotary vane-type pump. The rotor has a four-vane design, which allows the unit to create pressure in a compact body. This type of construction is practical for a starting pump because it is small, light and able to generate the required pressure quickly at high rotational speed. The pump is mounted directly on the upper part of the engine accessory gearbox / drive housing, so correct installation and drive engagement are important for reliable operation.

NP9 installation on AI-9 engines

The NP9 is used on AI-9 gas-turbine engines and auxiliary power units of different modifications. AI-9 units are installed on helicopters such as Ka-27, Ka-32 and Mi-8, and also on Yak-40 passenger aircraft. The exact pump installation and associated fuel-start components depend on the engine version and aircraft configuration. Before replacement, the pump designation, rotation direction, mounting interface and aircraft / engine documentation should be checked.

Operating conditions of the NP9 fuel pump

The NP9 works with aviation kerosene grades T-1, TS-1 and RT according to the applicable fuel specification. It is designed for operation in a wide temperature range, including low fuel temperature and high ambient temperature around the engine area. Since the pump is small and runs at high rotor speed, clean fuel and correct inlet pressure are important. Contaminated fuel, air in the line, inlet restriction or wear of the vane mechanism can affect pressure and starting reliability.

Inspection and supply of NP9

For procurement or replacement, the pump should be requested by its full designation NP9 / НП9. It is useful to confirm the required engine version, aircraft type, condition and documentation before shipment. The pump may be supplied new, from storage, repaired, overhauled or tested serviceable depending on availability. Before installation, it should be checked for free rotation, outlet pressure, inlet and outlet condition, signs of corrosion, vane mechanism condition, drive condition and compatibility with the AI-9 fuel-start system.