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

4. Open the Vacuum Control valve to make the Altimeter section climb. This climb
may be done rapidly without damage to the sensor.
5. When the Altimeter reads at least 18,000 feet, gently close the Vacuum Control
valve.
6. Wait for 2 minutes or more for the internal pressure to stabilize. Note: a rapid
climb will not damage the tester. However, the internal tubing needs time to
contract due to the applied vacuum, and this will give the appearance of a small
leak for the first 2 minutes or more. Rapid temperature changes will also mimic a
leak.
7. Perform a leak check to monitor the leak rate. Verify that the PS-500 does not
leak exceeding 100 feet per minute. Write down the leak rate for future reference.
(Subtract this value from the total leak rate when testing the aircraft, to arrive at
the aircraft's leak rate.)
8. Open the Vacuum Vent valve to bring the test box back to ground (ambient)
pressure.
Pre-test the pressure system of the PS-500 test box according to the following steps:
1. Turn on the power to the PS-500.
2. Ensure the PS-500 is not connected to any external hoses or devices.
3. Close the Vacuum Control, Vacuum Vent, Pressure Control, Crossbleed valve,
and Pressure Vent valves.
4. Turn on the Pressure Pump switch until the Pressure Reservoir gauge reads 10
PSI or more.
5. Open the Pressure Control valve to make the Airspeed section climb. This climb
may be done rapidly without damage to the sensor.
6. When the Airspeed reads at least 300 knots, gently close the Pressure Control
valve.
7. Wait for about 15 seconds for the internal pressure to stabilize. Activate the leak
check function to monitor the leak rate. Verify that the PS-500 does not leak
exceeding 2 knots per minute. Write down the leak rate for future reference.
(Subtract this value from the total leak rate when testing the aircraft, to arrive at
the aircraft's leak rate.)
8. Open the Pressure Vent valve to bring the test box back to ground (ambient)
pressure.
Testing Aircraft Pitot System Only
NOTICE! The Mach airspeed reading is only accurate at the altitude of 0 feet (sea level)!
1. Turn on the power to the PS-500.
2. Connect the Pressure Port to the aircraft Pitot system.
3. Close Pressure Control, Pressure Vent, and Crossbleed valves. Open Vacuum
vent valve.
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