OPERATION AND MAINTENANCE MANUAL For Model PS-625
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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

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

WARRANTY AND LIABILITY STATEMENT Preston Pressure LLC warrants its products against defects in workmanship and material under normal, intended use for a period of two years from the date of purchase. The batteries are warranted for a period of 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. Preston Pressure shall not be liable for any consequential damage...

CHAPTER 1 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. The PS-625 is battery powered and portable. The vacuum and pressure sources are derived from independent internal pumps, and each has its own reservoir. The tester can...

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. The test box can be used while it is charging and may be mounted in any position or angle. A battery monitoring circuit is also incorporated. This will flash “Low Battery” on the display if the...

FRONT PANEL LAYOUT DO NO! Om-TIGHTEN VALVES USE FINfifHTIP PH ESS1iHF ONLY 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. The LEAK CHECK button is functional only when in the Altimeter mode. Pressing this button will begin a 120 second timer, and the display will also show the gain or loss of altitude experienced...

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. The LEAK CHECK button is functional only when in the Airspeed mode. Pressing this button will begin a 120 second timer, and the display will also show the gain or loss of airspeed experienced during the displayed time period. If the operator wishes to select a different...

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.  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. The vent valves allow for metering the produced vacuum or pressure back into the atmosphere. One...

the test box and the altimeter. The vacuum and pressure reservoir gauges serve only as general references of reservoir vacuum and pressure; they are not used in the actual calibration of any instrumentation, and do not require calibration. Once sufficient vacuum is obtained in the reservoir, the pump is turned off, and the Vacuum Valve is gently opened to allow air to be suctioned into the system through the vacuum port. Once sufficient altitude simulation is obtained, the Vacuum Valve is gently closed. Reduction in altitude is accomplished by gently opening the Vacuum Vent Valve and...

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. The operator may substitute these procedures with others, as applicable to the tests to be performed, or according to other specific documentation. Error codes display as follows:  Altitude displays “Too High” if it exceeds 65,500 feet.  “Inverse Pressure” will be indicated on the airspeed side if the...

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-625 test box according to the following steps: 1. Turn on the power to the PS-625. 2. Ensure the PS-625 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...