Summary of Contents for PRESTON PRESSURE ALT-621
- Page 1 ALT-621 ASP-621 Digital Indicators OPERATION AND MAINTENANCE MANUAL prestonpressure.com Revision 5, December, 2019...
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Page 2: Table Of Contents
PRESTON PRESSURE LLC ALT-621/ASP-621 USER AND MAINTENANCE MANUAL TABLE OF CONTENTS Page Warranty and Liability Statement--------------------------------------------- 1. General Information------------------------------------------------------------------- 3 1. Description --------------------------------------------------------------------- 3 2. Models covered --------------------------------------------------------------- 3 3. Specifications ------------------------------------------------------------------ 4 4. Front Panel Description ------------------------------------------------------- 5 2. Operation -------------------------------------------------------------------------------- 6 3. -
Page 3: Warranty And Liability Statement
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
CHAPTER 1 GENERAL INFORMATION The ALT-621 is a digital display tester used to test aircraft altimeters. Altitude is displayed in feet and meters, with increments of 2, and 5 feet. The ASP-621 is a digital display tester used to test aircraft airspeed indicators. Airspeed is displayed miles per hour, kilometers per hour, and knots. -
Page 5: Specifications
Leak test feature: 2 minutes, selectable down to 30 seconds VSI (vertical speed indicator) 20 to 10000 The ALT-621 and ASP-621 indicators can be mounted in any position, at any angle. Note: The ALT-621 and ASP-621 indicators do NOT have the precision required to test RVSM altimeter systems. -
Page 6: Front Panel Description
Front Panel Description The UNITS button is used to toggle between the various units of measurement. The UNITS button on the ALT-621 will toggle between a display of feet, meters, mbars, and inHg. The UNITS button on the ASP-621 will toggle between a display of MPH, KPH, or Knots. -
Page 7: Operation
CHAPTER 2 OPERATION Prior to using the ALT-621 or ASP-621 indicator, the user should read this manual in its entirety. Select the desired units of pressure measurement by pressing the UNITS button as needed. A leak check may be initiated by pressing the LEAK CHECK button. This will display a 120 second timer, and the display will also show the gain or loss of altitude or airspeed experienced during the displayed time period. -
Page 8: Calibration Procedures
The calibration will not be lost when power is removed. Altimeter Calibration Procedures 1. Apply power to the ALT-621. Go to the mBar display, and allow the unit to warm up for a minimum of 15 minutes. 2. Connect a known altitude pressure standard to the Vacuum Port. - Page 9 Use this to fine-tune the altitude as close as you can to the standard. When the ALT-621 altitude matches the standard as close as possible, wait another 15 seconds to ensure that the internal mathematical filtering corrections have been done. If satisfied with the results, press the Units button to save the selected correction, and the display will automatically proceed to the next calibration level.
- Page 10 18000 1000 20000 1500 22000 2000 25000 3000 30000 4000 35000 6000 40000 8000 45000 10000 50000 12000 ALT-621 FOR TEST DISPLAY FOR TEST DISPLAY ALTITUDE ALTITUDE ALTITUDE ALTITUDE - 1000 14000 16000 18000 1000 20000 1500 22000 2000 25000...
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Page 11: Airspeed Calibration
Airspeed Calibration Procedures 1. Apply power to the ASP-621 display and allow unit to warm up for a minimum of 15 minutes. 2. Connect a known pressure standard to the Pressure and Static ports. Both ports should be sensing the same pressure. The calibration steps 6 and 7 will be repeated once for each sensor. - Page 12 When the pressure matches the standard as close as possible, wait another 15 seconds to ensure that the internal mathematical filtering corrections have been done. If satisfied with the results, press the Units button to save the calibration. 7. If this is the first sensor calibration (the Pitot sensor), the display will indicate again the same display as in step 5.
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Page 13: Maintenance And Troubleshooting
CHAPTER 4 MAINTENANCE AND TROUBLESHOOTING Normal maintenance is limited to performing calibration checks, and re-calibration if necessary. Refer to the following chart of symptoms, causes, and repair comments: SYMPTOMS POSSIBLE CAUSES COMMENTARY Display shows garbage Microcontroller had a Re-cycle power. power brown-out Display never...
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