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PRESTON PRESSURE PS-625 Operation And Maintenance Manual

Pitot-static/air data tester
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PS-625
Pitot-Static/Air Data Tester
OPERATION AND MAINTENANCE
MANUAL
For Model PS-625
prestonpressure.com
Revision 1, September, 2020

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Summary of Contents for PRESTON PRESSURE PS-625

  • Page 1 PS-625 Pitot-Static/Air Data Tester OPERATION AND MAINTENANCE MANUAL For Model PS-625 prestonpressure.com Revision 1, September, 2020...

  • Page 2: Table Of Contents

    PRESTON PRESSURE LLC PS-625 USER AND MAINTENANCE MANUAL TABLE OF CONTENTS Page Warranty and Liability Statement---------------------------------------------------- 2 1. General Information------------------------------------------------------------------- 3 1. Specifications ------------------------------------------------------------------ 3 2. Power Supply ------------------------------------------------------------------ 4 3. Vacuum and Pressure Pumps ------------------------------------------------ 4 4. Front Panel Layout------------------------------------------------------------- 5 5.

  • Page 3: Warranty And Liability Statement

    90 days from the date of purchase. Valves are warranted for a period of 180 days. Preston Pressure’s limit of liability shall be to repair or replace the product at their discretion. Transportation shall be pre-paid to the Preston Pressure factory or authorized service facility.

  • Page 4: General Information

    GENERAL INFORMATION Description of the PS-625 Pitot-Static Air Data Test Box The PS-625 Air Data, pitot-static test box is a digital display tester used to test aircraft altimeters, airspeed indicators, pitot-static systems, and other vacuum and low-pressure devices. This test box incorporates transducer sensor technology that is largely immune to the failures and costly repairs associated with analog instruments.

  • Page 5: Power Supply

     Power Supply The PS-625 power supply consists of an external transformer with an output of 12 volts DC. This supply is plugged into the round connector on the tester front panel. The transformer charges the 12-volt gel-cell lead acid battery internal to the PS-625. The battery enables the test box to be used in a portable fashion, without a need for external power while the tester is in operation.

  • Page 6: Front Panel Layout

    FRONT PANEL LAYOUT Front Panel Description  The front panel Altitude buttons function as follows: The UNITS button is used to toggle between the various units of measurement available from the vacuum/altimeter section. (Altitude in feet, Altitude in meters, mBar, mmHg, inHg, PSIA) The EXIT button is used to exit out of the leak check mode.
  • Page 7 The UNITS button is used to toggle between the various units of measurement available from the pressure/airspeed section. (Airspeed in MPH, Knots, KPH, mBar, mmHg, inHg, PSIA, EPR) NOTICE! The Mach airspeed must be measured at the altitude of 0 feet (sea level)! The EXIT button is used to exit out of the leak check mode.

  • Page 8: Theory

    CHAPTER 2 THEORY The PS-625 test box consists of two vacuum pumps linked in series, one pressure pump, reservoirs for the pressure and vacuum, a system of metering valves, and digital displays for indicating altitude, airspeed, and various other pressure measurements, based on pressures sensed in the sensor transducers.

  • Page 9: Electronic Theory

     Electrical Theory One internal gel-cell lead-acid battery provides the power to the PS-625 test box. The battery is charged via the power connector on the top panel of the test box. Full charging time is about 10...

  • Page 10: Operation

    OPERATION  Preliminary Information Prior to using the PS-625 tester, the user should become familiar with the unit by reading this manual and operating the tester independently of any other attached devices. The test procedures described in this manual are general in nature, for reference use only.

  • Page 11: Testing Aircraft Pitot System

    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-625 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.)

  • Page 12: Testing Aircraft Static System

    Note: First ensure pitot system does not leak by performing Pitot system test on page 14. 1. Turn on the power to the PS-625. 2. Connect the Vacuum Port to the aircraft static port, and the Pressure Port to the aircraft pitot port.

  • Page 13: Using The E.p.r. Function

    The EPR function is used to test engine pressure ratios. This ratio is the mathematic result of: High Pressure/Low Pressure. The PS-625 test box will display the low pressure, the high pressure (both in PSI), and the resulting EPR. To use the EPR function, proceed as follows: 1.

  • Page 14: Calibration Procedures

    Calibration Procedures The PS-625 test box is easy to calibrate. There are 7 set points used in the calibration of the altimeter side. Calibrating at multiple setpoints enables the altimeter to have a greater degree of accuracy, allowing it to self-correct to the nearest calibrated set point.
  • Page 15 When the PS-625 altitude matches the standard as close as possible, press the Units button to proceed to the next calibration level. Repeat the same adjustment at each requested altitude point.
  • Page 16 Airspeed Calibration Procedures 1. If not already powered, apply power to the PS-625 and allow the unit to warm up for a minimum of 10 minutes. 2. Gently close the Pressure Control valve, Pressure Vent valve, and Crossbleed valve. 3. Connect a known pressure standard to the Pressure and Vacuum Ports.
  • Page 17 The displayed airspeed accuracy tolerance must be within these values: +/- 1.0 knots @ 20 knots +/- 0.5 knots @ 50 knots to 650 knots If the accuracy is out of the allowed tolerance, either adjust the calibration again or make a correction chart for the operator to reference.

  • Page 18: Maintenance Repairs And Troubleshooting

    CHAPTER 5 MAINTENANCE REPAIRS AND TROUBLESHOOTING Note: Refer to the Theory of Operation section as a reference on how the various systems function. Annual Maintenance The following annual maintenance is recommended: 1. Check color of beads in air reservoir/dryer. Change if pink or clear. The dryer is a common in- line dryer used in small air compressor systems.
  • Page 19 problem occurs frequently, it may be caused by a loose or dirty internal connector. Check connectors to battery and circuit board. Also check for a loose fuse. Display never finishes 1. Tester is being operated 1. Operate the tester in a initializing conditions that...

  • Page 21: Shipping And Storage

    CHAPTER 6 SHIPPING AND STORAGE Shipping Instructions  Partially open all valves  Ensure power switch is off  Package the test box inside another box, with at least 2 inches of packing material around the tester  Do not forget to also enclose the battery charger/power supply ...

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