manually operated. Their status, however, is monitored
from the control consoles.
Routine maintenance of the bleed air control valves
usually consists of cycling the valves to check for proper
operation. If a valve fails to cycle or fails to display the
proper status indication, you, the GSE, will be called.
As mention earlier, the bleed air system consists of
Refer to chapter 5 of this TRAMAN for specific
several parts. The parts that are of primary concern to
m a i n t e n a n c e procedures used with solenoids and
the GSEs are the control valves. Consequently, our
microswitches. Always use the appropriate technical
discussion will be limited to the maintenance and repair
manual when working on control valves.
of these valves. You should refer to chapter 5 of this
TRAMAN for a detailed discussion of the maintenance
and troubleshooting procedures for control valves.
The bleed air control valves are located throughout
When you are called to troubleshoot a
the bleed air system. They control the flow of bleed air
malfunctioning bleed air control valve, make sure you
through the system.
get all the symptoms from the operating personnel. First,
Most of the control valves are pneumatic
y o u must know what the operator was trying to
accomplish. In some instances, certain permissive must
be met before a control valve will cycle. Sometimes the
shutoff valves. An example of a typical bleed air control
problem is not with the valve but with the system
valve is shown in figure 4-4. Atypical bleed air control
valve consists of a shutoff assembly and an actuator
assembly. The shutoff assembly consists of the valve
Troubleshooting procedures for bleed air control
body and the butterfly vane. The actuator assembly
valves include inspecting, testing, and repairing the
consists of the solenoid-operated pilot valve and the
solenoids and microswitches. Specific procedures used
actuating piston and control linkage. A spring-loaded
to maintain and troubleshoot solenoids and
microswitch is also provided to show the valve status on
m i c r o s w i t c h e s are discussed chapter 5 of this
the ECSS, PCS, or MCS equipment.
Figure 4-4.--Typical bleed air control valve.