TEST CHAMBER ASSEMBLY, MODEL 452
OPERATION UNDER USUAL CONDITIONS
INITIAL ADJUSTMENT BEFORE USE
5. Turn the PRESSURE CONTROL regulator (10) on the test chamber fully counterclockwise to
If the test chamber will not maintain altitude, there is a leak in the pneumatic
system. Ensure that compression nuts are hand tight and that the altitude
chamber gasket is not damaged. DO NOT USE WRENCHES. If the chamber
still does not maintain altitude, send it back to depot for repair.
6. Move the CLIMB/FALL/COCK switch (8) on the test chamber to FALL position. Verify that
the altitude reading remains at 6,500 feet or that it falls less than 100 feet in ten seconds.
7. Move the CLIMB/FALL/COCK switch (8) to CLIMB.
8. Turn the PRESSURE CONTROL regulator (10) on the test chamber clockwise to obtain 15
PSI on the PRESSURE GAGE (11).
9. Move the CLIMB/FALL/COCK switch (8) on the test chamber to FALL and, using a
stopwatch, record the time it takes for the altimeter to fall from 6,000 to 5,000 feet.
10. Calculate the rate of fall in ft/sec by dividing 1,000 by the stopwatch time. Using an erasable
marker, soft pencil, or other suitable instrument, transfer the pressure value from the
PRESSURE GAGE (11) and the rate of fall to the appropriate spaces on the FUNCTIONS
decal (9) on the test chamber.
11. Move the CLIMB/FALL/COCK switch (8) to CLIMB.
12. Change the reading on the PRESSURE GAGE (11) to a higher or lower value as required.
13. Repeat steps 9 through 12 as required to obtain rate of fall information within the desired
To protect altimeter from damage, do not press rapid fall dump switch at altitudes
greater than 25,000 feet.
14. Move CLIMB/FALL/COCK switch (8) to FALL, and increase pressure in altitude chamber to
ambient by holding down on RAPID FALL DUMP switch (7).
15. Position test chamber ON/OFF switch (5) to OFF.
16. Open lid (1) of altitude chamber and remove AR2 (3).
17. Prepare AR2 for storage or movement (WP 0023 00).
18. Altimeter calibration. If altimeter (4) calibration is required, refer to (WP 0021 00 for removal