Fuel System -Cont. - P-307

CHAPTER FOUR

T-34C AIRCRAFT SYSTEMS FAMILIARIZATION

WORKBOOK

Maintain a proper fuel-air mixture.

The output of the FCU enters the fuel flow divider and then the fuel manifold, which consists of

the fuel nozzles and their connecting lines. There are 14 fuel nozzles that atomize the fuel for

optimum ignition in the combustion chamber. Ten of the nozzles are called primary nozzles and

are utilized for starting. The four secondary nozzles augment the primary nozzles after engine

start.

The fuel flow divider is the device that limits fuel flow to only the 10 primary nozzles during

engine start. As engine speed increases during start, fuel pump pressure increases, moving a

one-way check valve to allow fuel flow to the secondary nozzles (approximately 40% N1).

There is a manifold dump valve located within the fuel flow divider to purge the manifold of

residual fuel upon engine shutdown. This residual fuel is collected in a fuel scavenge tank

located on the right side bottom of the firewall and covered by the air conditioning condenser.

When the tank is full, an internal float switch energizes an electric (28-VDC) scavenge pump

which returns the fuel to the sump tank.

4-6 FUEL SYSTEM