including those at the aircraft quick disconnects. Close
Operational Checks
all the access doors to protect instruments and controls.
When operating the test stand, you need to
Multisystem Operation
periodically check the condition of system fluid
through the sight glass. If you see evidence of air,
When performing troubleshooting, rigging, and
bleed the system at both the test stand and air bleed
specific tests on dual flight control systems that have
points in the aircraft until the fluid appears clear. Also,
tandem actuators, you often need to apply SE hydraulic
you need to monitor the filter differential pressure
pressure to two or three systems in an aircraft at the
indicators, particularly those associated with the
same time. Simultaneous, multisystem operation
3-micron filter assemblies. In some cases, loaded filter
involves using separate hydraulic test stands for each
indicators may extend due to cold starting conditions.
system, or by manifolding two or more systems to a
Reset the indicator and continue to monitor it until the
common test stand that has a sufficient flow capability.
equipment reaches the normal operating temperature.
Less equipment is needed with the latter method, but it
If a loaded filter is indicated, shut down the equipment
has several limitations that you should know.
and return it to the supporting activity. Another
condition that would require you to return the
If you use a single test stand and manifold,
equipment to the supporting activity is if the fault
hydraulic fluid between the connected systems is
indicators light; in this case, shut down the unit and
exchanged. If the fluid in one system is contaminated
return it to the supporting activity. In case of an
with particulate matter smaller than 3 microns,
emergency (for example, a ruptured hydraulic hose in
cross-contamination of the other system(s) will occur.
Using a single test stand may not satisfy differing flow
aircraft), you should open the bypass valve to relieve
and back pressure requirements of the multiple
pressure and stop the flow of hydraulic fluid to the
systems to be powered. Depleting or overfilling
aircraft. Pay attention to warning signs, such as a
aircraft reservoirs might result. If a single test stand is
sudden drop in engine oil pressure or any unusual
used, high transient flow demands in one system could
engine noise. If any engine part fails, stop the engine
adversely affect the performance of the other systems.
immediately.
Total isolation between systems could possibly
degrade critical flight control system performance
Shutdown Procedures
tests. The use of jury-rigged manifolds not specifically
In aircraft equipped with pressurized reservoirs,
engineered for the purpose is a safety hazard to
hydraulic accumulators, or surge dampers, a reverse
personnel and a possible source of system
flow of fluid through the aircraft filters could damage
contamination. Properly designed hydraulic
the system. You need to use the correct shutdown
manifolds can be used in limited, specific applications
procedures. When you have finished the required
to power multiple hydraulic systems to form a common
aircraft tests, leave the bypass valve in the closed
hydraulic test stand. This configuration must be
evaluated by the cognizant engineering activity to
position. Reduce the volume setting to zero and adjust
make sure it is acceptable and that its use is strictly
the pressure compensator to minimum. Allow several
limited to that particular application. All approved
minutes for stored pressure in the aircraft to bleed off,
manifold use must be directed in the applicable aircraft
via normal internal leakage. On stands equipped with a
MIM, and complete information on the source of the
pressure and return line shutoff valve, close the valve
required hardware must be provided. Do not use
i n s t e a d o f r e d u c i n g t h e vo l u m e a n d p r e s s u r e
manifolds that are not authorized.
compensator.
Q9-10. What is the purpose of a portable hydraulic
Slowly open the pressure bypass valve. Let the
test stand?
engine run at 1,000 rpm for about 5 minutes
(engine-driven models only), then push the throttle
Q9-11. What is the power source of the A/M27T-5
down completely. Place the panel light switch in the
portable hydraulic power supply unit?
OFF position. Remove the external hoses from the
Q9-12. What is the purpose of the emergency stop
aircraft hose ports. Connect one end to the hose
handle on the A/M27T-5 unit?
storage manifold disconnects on the test stand. Do not
drag the hose ends on the deck or expose them to
Q9-13. What is the range of the high-pressure gauge
contamination. Install all dust caps and plugs,
on the A/M27T-5 unit?
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