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Preston PS-425 Operation And Maintenance Manual

Pitot-static/air data tester
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PS-425
Pitot-Static/Air Data Tester
OPERATION AND MAINTENANCE
MANUAL
Preston Pressure LLC
580-286-3161
prestonpressure.com
Revision 1, February 16, 2011
PRESTON PRESSURE LLC

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Summary of Contents for Preston PS-425

  • Page 1 PS-425 Pitot-Static/Air Data Tester OPERATION AND MAINTENANCE MANUAL Preston Pressure LLC 580-286-3161 prestonpressure.com Revision 1, February 16, 2011 PRESTON PRESSURE LLC...

  • Page 2: Table Of Contents

    PS-425 USER AND MAINTENANCE MANUAL TABLE OF CONTENTS Page Warranty and Liability Statement---------------------------------------------------- 2 1. General Information------------------------------------------------------------------- 3 2. Specifications ------------------------------------------------------------------ 4 3. Front Panel Layout------------------------------------------------------------- 5 4. Front Panel Description ------------------------------------------------------- 6 2. Theory------------------------------------------------------------------------------------- 7 3. Operation -------------------------------------------------------------------------------- 8 1.

  • Page 3: Warranty And Liability Statement

    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-425 Pitot-Static Test Box The PS-425 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: Specifications

    Leak test feature: 2 minutes, selectable down to 30 seconds (longer test periods available upon request) VSI (vertical speed indicator) : Increments of 2 when < 100 feet/minute; increments of 25 when > 100 feet/minute. Limited to 9,900 ft/minute Note: The PS-425 does NOT have the precision required to test RVSM altimeter systems.

  • Page 6: Front Panel Layout

    FRONT PANEL LAYOUT...

  • Page 7: Front Panel Description

    Front Panel Description The UNITS button is used to toggle between the two primary display modes. Upon powering up, the display indicates altitude in feet and airspeed in knots. Pressing the UNITS button will switch the display to indicate altitude in feet and vertical speed per minute in feet.

  • Page 8: Theory

    CHAPTER 2 THEORY The PS-425 test box consists of one manual vacuum pump, one manual pressure pump, reservoirs for the pressure and vacuum, and a digital display for indicating altitude and airspeed. • Pneumatic Theory Metering valves allow the operator to control the rate of flow of the air from the pressure or vacuum sources, exiting out through the vacuum and pressure ports.

  • Page 9: Operation

    OPERATION • Preliminary Information Prior to using the PS-425 tester, the user should become familiar with the unit by reading this manual and operating the tester independently of any other attached devices. For greater accuracy, the indicator should be powered on for 15 minutes before use.

  • Page 10: Testing Aircraft Pitot System

    7. The leak check function will activate and begin to monitor the leak rate. Verify that the PS-425 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.)

  • Page 11: Testing Aircraft Static 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-425. 2. Connect the Vacuum Port to the aircraft static port, and the Pressure Port to the aircraft pitot port.
  • Page 12 3. Close Vacuum Control, Vacuum Vent, Pressure Control, and Pressure Vent valves. Open Crossbleed valve. 4. Actuate the Vacuum Pump until a desired level of vacuum is seen on the Vacuum Reservoir gauge (generally -15 to -20 inHG). Actuate the Pressure Pump until the Pressure Reservoir indicates 15 PSI or more.

  • Page 13: Calibration Procedures

    The PS-425 is easy to calibrate. There are 5 set points used in the calibration of the altimeter. This enables the altimeter to have a greater degree of accuracy, allowing it to self-correct to the nearest calibrated set point.
  • Page 14 “Storing” and then re-start. There is no need to re-cycle power. 9. After bringing the PS-425 back down to ground level pressure, wait at least 1 minute for settling. Then, test each calibration point as specified in the chart on page 14. Enter the corrected value at each point.
  • Page 15 -1000 14000 16000 18000 1000 20000 1500 22000 2000 25000 3000 30000 4000 35000 6000 8000 10000 12000 PS-425 S/N FOR TEST DISPLAY FOR TEST DISPLAY ALTITUDE ALTITUDE ALTITUDE ALTITUDE - 1000 10000 12000 14000 1000 16000 1500 18000 2000...

  • Page 16: Airspeed Calibration

    Airspeed Calibration Procedures 1. Perform the altimeter calibration described in the previous section. The pitot sensor is calibrated in this process, along with the static sensor. 2. When a satisfactory altitude calibration is obtained, go through each test point in the following chart, and enter the corrected value at each point.

  • Page 17: Maintenance Repairs And Troubleshooting

    1. Check color of beads in air reservoir/dryer. Change if pink. The dryer is a common in- line dryer used in small air compressor systems. A new dryer can be purchased from Preston Pressure, or an internet search for “mini inline desiccant air dryer” may lead to an alternate source.
  • Page 18 excessively cold. 2. Low battery Unit will not vacuum up to 1. Leak in internal hoses or 1. Troubleshoot plumbing 35,000 feet plumbing connectors to find leak(s) 2. Cylinder pump is weak or Replace defective inoperative cylinder...

  • Page 19: 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 • Tester is not likely to be damaged with ground shipping if packaged properly Storage Instructions •...

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