T53 – Fuel Flow Divider

Identification & Location

The Flow Divider can be found on the exhaust diffuser support cone Assembly mounting bracket at the 6 o’clock position.

System Design

The Fuel Control Unit delivers fuel to the inlet of the Flow Divider Assembly. Then the Fuel Flow Divider divides the fuel to the right and left side of the Main Fuel Manifolds.

At low N1 speeds, the flow divider sends fuel through the primary system of the manifolds. As N1 speed increases, fuel pressure increases, and the Flow Divider opens ports to the secondary system of the Main Fuel Manifold. The flow divider is equipped with a drain port to drain fuel from the Main Fuel Manifolds and Flow Divider during engine shutdown.


The main fuel system receives its fuel from an airframe mounted boost pump which pumps fuel directly through an airframe mounted filter and then to the FUEL CONTROL. From the FCU, main fuel flow is routed by external line through the main fuel Flow Divider and dump valve assembly. The Flow Divider and dump valve assembly has a lower housing containing the dump valve and an upper housing containing the flow divider.

The Flow Divider controls fuel flow to the engine nozzles according to a predetermined schedule of secondary flow versus primary flow.
A dump valve was incorporated as an integral unit to drain the fuel from the manifolds and fuel lines following engine shutdown.
The flow divider and dump valve assembly is designed to function with fuel pressures up to 1200 psig.

When fuel pressure at the inlet of the flow divider reaches a predetermined value (approximately 8 to 12 percent N1), the dump valve plunger moves to a closed position, allowing fuel to enter the flow divider valve. Fuel then passes through orifices in the flow divider plunger and out to the primary Manifolds. When the primary flow reaches a predetermined value (approximately 32 percent N1), the pressure at the plunger face is sufficient to move the plunger off its seat. As the plunger is displaced, the secondary flow ports in the flow divider body are progressively opened, allowing fuel to pass into the secondary Manifolds.


Fuel leaking from the combustion chamber drain valve during an engine operation should be evaluated for Overhaul or Repair. (RFQ)