Figure 4-9.-Interior lighting.
Another
method
of
instrument
lighting
Rheostats control the intensity of light in most
(commonly called post lighting) uses installation of
aircraft (fig. 4-8). The rheostat is a variable resistor
specially adapted shields in front of the instruments.
used to limit current through the circuit. When the
Small lamps in red-filtered sockets mount in the front
pivoting arm reaches the high-resistance end of the
surface of the cover shields, which cast light down and
rheostat, it slips off the contact surface and breaks the
onto the instruments. These shields mount around the
circuit. This arrangement is a rheostat switch.
instrument for vision and are flanged to direct the
A typical aircraft instrument lighting system is
lights properly for dial illumination.
shown in figure 4-9. You should refer to this
4-9
