Testing Aircraft Static System - PRESTON PRESSURE PS-500 User And Maintenance Manual

4. Turn Pressure Pump switch on until the Pressure Reservoir indicates 10 PSI or
more.
5. Gently open Pressure Control valve until desired speed(s) are achieved.
6. Compare the airspeed of the PS-500 box to the airspeed indicated in the aircraft.
7. Go to approximately 75% of the maximum airspeed of aircraft indicator (or the
speed specified by the manufacturer). Close the Pressure Control valve and after
allowing a few seconds for stabilization, perform a leak check. The pitot system
should not leak more than two knots per second, plus the leakage previously noted
in the pressure system pre-test.
8. Gently open the Pressure Vent valve to return the pitot pressure to ambient
pressure.
Testing of Aircraft Static System (independent from the pitot system)
Note: If the previous pitot system test indicated an excessive leak, do not proceed until
that leak is repaired. Damage to aircraft airspeed indicator could result.
1. Turn on the power to the PS-500.
2. Disconnect the static line to the airspeed indicator and cap the line.
3. Connect the Vacuum Port to the aircraft static port. Set the aircraft altimeter to
29.92 inHg (1013.3 mB).
4. Close Vacuum Control, Vacuum Vent, Pressure Control, and Pressure Vent
valves. Open Crossbleed valve.
5. Operate the Vacuum Pump switch until a desired level of vacuum is seen on the
Vacuum Reservoir gauge (generally -15 to -20 inHG). Turn Pressure Pump switch
on until the Pressure Reservoir indicates 10 - 15 PSI or more.
6. Gently open the Vacuum Control valve to cause the altitude to climb.
7. DO NOT exceed the climb rate of the aircraft VSI indicator, or the airspeed
indicator limits. The VSI is a very delicate instrument.
8. Climb to the desired altitude(s) per the test to be performed.
9. Close the Vacuum Control valve, and after allowing a few seconds for
stabilization, compare the aircraft altimeter with the test box.
10. When at the appropriate altitude (generally 18,000 feet) perform a leak check. If
the static system shows leakage, be careful to not exceed the VSI rate. Be
prepared to open the Vacuum Control valve if needed, to prevent excessive VSI
indication.
11. Gently open the Pressure Vent valve to return the system pressure to ambient
pressure. Do not exceed the VSI or airspeed indicator limits.
12. Re-connect airspeed indicator static line and do a leak check test.
Note: if an altitude lower than ambient pressure is desired, do steps 1-4 above. Gently
open the Pressure Control valve to pressurize the system, thereby causing the
altimeter to decrease in altitude. Open the Vacuum Vent valve to return to ambient
pressure.
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