LUBRICATION SYSTEM. The TF40B lubri-
cation system consists of the sump module, an accessory
pickup is located inside the inlet housing. The pickup
gearbox module driven lube and scavenge pump, an
signals, fed to the electronic control system, provide
visual speed readout signals along with engine control
engine-mounted oil cooler assembly, the necessary
piping, and a lube filter assembly. The lube and scavenge
and governing functions.
pump draws oil from the sump module and delivers it to
FUEL SYSTEM. The major function of the
the oil cooler assembly. The oil then flows from the oil
engine fuel system is to provide fuel to the atomizing
cooler assembly into the oil inlet port where it surrounds
combustor chamber assembly at a specific, regulated
the lube filter assembly, which contains a 7-micron
flow rate to ensure optimum engine performance at all
element. The oil flows through the filter, up through the
stages of operation. The basic components of the fuel
core, and out of the oil outlet port to the oil distribution
system are the fuel valve assembly (consisting of the
block. From here, the oil flows into the accessory
fuel valve, limiter, and actuator), connecting hoses,
gearbox module and inlet housing module to lubricate
main fuel and redundant valves, oil cooler assembly,
high-pressure fuel filter, fuel flow divider, fuel return
filter becomes clogged, the oil is bypassed. Located in
the head assembly is a differential oil pressure switch,
nozzles.
which actuates at 13 to 19 psid, and a bypass valve,
Filtered fuel flows from the fuel valve assembly. It
which opens at 21 to 29 psid if the filter becomes
then flows through the fuel solenoid valve, oil cooler
clogged and can no longer function. The differential oil
assembly, and redundant fuel solenoid valve. Next, it
pressure switch will actuate just before bypass to
flows into the fuel flow divider that provides primary
illuminate an oil filter warning light on the instrument
and secondary fuel flow to the fuel injection nozzles,
panel. This switch is mechanically locked until oil
which deliver the fuel into the atomizing combustor
temperature reaches 115 to 155F (46 to 68C) to
chamber assembly.
provide for warmup in cold weather conditions.
A pressure-actuated combustion chamber drain
External piping in the lubrication system also
valve assembly is mounted on the bottom perimeter of
supplies filtered oil to the power output shaft assembly
the atomizing combustor housing assembly. In the event
and to the compressor and power turbine bearings. A
of a shutdown, an aborted start, or engine flameout, this
scavenge oil pump mounted on the accessory gearbox
assembly automatically drains residual fuel from the
is integral to the lube and scavenge pump. The scavenge
combustion area. The fuel return solenoid valve
oil pump provides positive drainage of the No. 4 and
automatically reduces fuel flow to reduce the EGT
No. 5 bearing scavenge oil through external oil hose
during the start sequence only if EGT rises to the
assemblies and the lube monitor assembly to the top of
warning offset set point.
the inlet housing module. An external oil hose assembly
NOTE: This can also be done manually during the
provides gravity drainage of the No. 2 bearing scavenge
oil from the combustor and power turbine assembly to
start sequence or at any time during engine operation.
the sump module. The scavenge oil drains internally by
The operator positions the START/STOP switch to the
START position and holds it there.
gravity from all the other components through the
accessory gearbox module, inlet housing module, and
The high-pressure fuel filter assembly consists of a
compressor housing to the sump module. Electronic
throwaway 10-micron filter element and ahead and case
chip indicators in the No. 4 and No. 5 bearing oil
assembly. The fuel filter has a rated flow of 12 gallons
scavenge lines and in the sump module initiate warnings
per minute.
in case of metallic chip accumulation in the lubricating
The head assembly incorporates a stainless-steel
oil.
bypass relief valve that opens at 45 to 55 psid and a
ELECTRONIC CONTROL SYSTEM. The
differential pressure indicator that actuates a red pop-up
TF40B electronic control system provides for automatic
button at 30 to 40 psid to indicate the filter is clogged.
start and power control and monitoring of engine
The pop-up indicator has a thermal lockout feature for
operations. It also sequences automatic shutdown of the
temperatures from 20 to 50F (7 to 10C) to prevent
engine.
false indications in extremely cold conditions. If the
The electronic control system consists of a modular
pop-up indicator actuates, you must flush the filter case.
You must also replace the filter when you reset the
control box assembly, instrument and control panel, the
pop-up button.
associated wiring and cabling, and sensing and
6-6
