Distribution

The distribution system supplies the stored fuel to the engine. It also provides a way to shut off the fuel supply.

The distribution system consists of the components that follow:

• Shutoff valve

• Control cable assembly

• Shutoff valve bracket

• Feed line, pickup

• Fitting, feed line

• Feed line, tank-to-prime pump

• Prime pump

• Feed line, prime pump-to-shutoff valve

• Feed line, shutoff valve-to-engine

Shutoff valve

The shutoff valve is a two-way ball valve that shuts off the fuel supply to the engine, when necessary, in case of emergencies or during maintenance. It is located on the left side of the forward vertical firewall.

Control cable assembly

The control cable assembly has a tee-handle at the top of the windshield center post. It is installed in the ceiling of the helicopter and its other end is connected to the lever that operates the shutoff valve.

Shutoff valve bracket

The shutoff valve bracket supports the aft end of the control cable assembly. It is installed on the forward vertical firewall.

Pickup feed line

The pickup feed line is a flexible hose assembly with a strainer. It is located inside the fuel cell between the bottom center of the fuel cell and the feed line fitting. The strainer is located at a low point at the bottom of the fuel cell to use the most amount of fuel possible with the least amount of contaminants.

Feed line fitting

The feed line fitting connects the feed line inside the fuel cell to the feed line outside the fuel cell. It is located on the expansion plate.

Tank-to-prime pump feed line

The tank-to-prime pump feed line is a flexible hose assembly. It is located in the lower main rotor drive compartment, between the feed line fitting and the prime pump.

Prime pump

The prime pump supplies fuel to the engine during starts. It is located in the lower main rotor drive compartment, on a bracket on the deck above the baggage compartment.

Prime pump-to-shutoff valve feed line

The prime pump-to-shutoff valve feed line is a flexible hose assembly. It is located in the main rotor drive compartments, between the prime pump and the shutoff valve.

Shutoff valve-to-engine feed line

The shutoff valve-to-engine feed line is a flexible hose assembly. It is located inside the engine compartment, between the shutoff valve and the engine.

Operation

The prime pump circuit is energized with 28 VDC from the main bus and can be isolated with the FUEL PUMP circuit breaker.

During engine starts, the actions that follow occur:

• The crank relay is energized and supplies 28 VDC to the prime pump.

• Suction from the prime pump gets the fuel from fuel tank through the strainer on the pickup feed line, the fitting on the expansion plate, and tank-to-prime pump feed line.

• The fuel from the prime pump is fed to the engine through the prime pump-to-shutoff valve feed line, shutoff valve, and shutoff valve-to-engine feed line.

After the engine is started, suction from the engine fuel pump continues to pull fuel through the strainer on the pickup feed line, the fitting on the expansion plate, the tank-to-prime pump feed line, the prime pump, the prime pump-to-shutoff valve feed line, the shutoff valve, and the shutoff valve-to-engine feed line.

Operating the tee-handle on the control cable assembly moves the lever on the shutoff valve to stop the flow of fuel to the engine.