Figure 2-43.--Fuel shutdown valve.
psig greater than reference pressure, the valve
backflow into the No. 2 valve from the No. 1
opens. The upstream pressure (including servo
valve bypass line.
supply and stator actuation) is 190 psig or greater
before the pressurizing valve opens. This is
Purge Valve
adequate for proper operation.
The purge valve operates electrically. It is a
normally-closed, on-off valve used to drain low-
Fuel Shutdown Valves
temperature fuel from the system before a GTE
start. It is spring-loaded to the closed position;
The two fuel shutdown valves (fig. 2-43) are
a solenoid opens the valve when it is energized.
pilot-valve actuated and electrically controlled.
About 3 gallons of fuel are drained from the
The valves are piped hydraulically in series. They
system during purging.
are electrically operated in parallel by control logic
during an automatic sequence. The console
Fuel Manifold System
operator can also operate them at the LOP, the
PCC, or the PACC during a manual stop. Both
The fuel manifold system is shrouded. (The
valves must be energized to port metered fuel to
manifold and the manifold-to-fuel nozzle con-
nector tubes are tubes within a tube assembly.)
the GG fuel manifold. De-energizing either valve
If a fuel leak develops in the manifold system,
will bypass the fuel back to the pump inlet.
Normally, both valves are de-energized to shut
the leakage collects inside the shroud. It is then
down the engine. The second valve acts as a
drained through a drain line to a telltale drain
backup and will bypass fuel if the first should fail
under the enclosure base. Next it goes to a
to function. You can operate the two valves
collection tank. Fuel leakage inside the enclosure
from the manifold system is prevented and fire
independently from the LOP as a maintenance
check.
hazard is minimized by this system design.
Each shutdown valve has a pilot pressure bleed
relief valve to prevent backflow through the valve
Fuel Nozzles
during GTE motoring. A check valve which has
The LM2500 GTE uses 30 fuel nozzles to
a 2 psid cracking pressure is located in the bypass
port of the No. 2 shutdown valve to prevent fuel
admit fuel to the combustor. The fuel nozzle
2-37
