brush connects to a linkage within the nozzle area
thermometer. It consists of a bulb connected by
control and moves in relation to the variable
a capillary tube to a Bourdon tube and a
exhaust nozzle. Current in the resistance winding
multiplying mechanism connected to a pointer.
is picked up by the movable rush, and it varies
The pointer shows the oil temperature on a dial.
according to the location of the brush. Then, this
signal current goes to one of the indicator field
coils.
EXAUST NOZZLE INDICATING
SYSTEM
The indicator contains two field coils and
a rotor. The polarized rotor mounts on a
The exhaust nozzle position indicating system
free-moving shaft. The shaft is located in
shows the pilot engine variable exhaust nozzle
the center of the magnetic field created by the
position. This, in turn, provides a measure of
two coils. One coil connects to the transmitter
percentage of afterburning, since constant
potentiometer in the nozzle area control. The
temperatures are held throughout the afterburner
second receives a constant current to give
range.
smooth indicator operation. The rotor aligns
Each engine has a separate but identical nozzle
itself with the magnetic field. The magnetic
position indicating system. Each system consists
field varies as the signal received from the
of a transmitter potentiometer in the nozzle area
potentiometer varies. A pointer mounted on
control unit and an indicator on the main
the rotor shaft shows rotor position in relation
instrument panel. Power for the system is from
to nozzle position.
the essential 28-volt dc bus.
Each indicator is a hermetically sealed unit
TORQUEMETER SYSTEMS
containing a single receptacle for a mating plug
electrical connection. The instrument scale ranges
The electric torquemeter system in turboprop
from OPEN to CLOSE, with markings at the 1/4,
aircraft measures the torque (horsepower)
1/2, and 3/4 positions (fig. 6-61).
produced by the engine at the extension shaft.
Each system consists of a transmitter (part of the
The transmitter potentiometer consists of a
engine extension shaft), a phase detector, and an
resistance winding with a movable brush. This
Figure 6-61.-Exhaust nozzle position indicating system.
