diaphragm causes the reference regulator to
open. This results in pressure being passed
through the control orifice, which is regulated by
the cross-bleed start relief regulator (7). The
pressure commands the actuator section to
open with a corresponding opening of the
During deicing operations, control pressure
from the temperature control regulator valve is
applied to the temperature control connection (9).
This changes the shuttle valve position to allow
the temperature control regulator valve pressure
to open the actuator section and the butterfly.
During deicing operations, pressure from the
temperature control regulator valve overrides all
other inputs to the shuttle valve.
Bleed-Air Shutoff Valve
The bleed-air shutoff valve is a normally
closed, pneumatically operated, electrically
controlled shutoff valve with provisions for
automatic closure in the event of overtemperature,
overpressure, or loss of electrical power (fig. 4-3.)
Figure 4-3.-Bleed-air shutoff valve schematic.