TB 9-4920-457-35
c. Unless otherwise specified, verify the result of each test and, whenever the test
requirement is not met, take corrective action before continuing with the calibration.
Adjustments required to calibrate the TI are included in this procedure. Additional
maintenance information is contained in the manufacturers' manuals for this TI.
d. Unless otherwise specified, all controls and control settings refer to the TI.
7. Equipment Setup
a. Place TI on a level platform or bench with instruments face up.
b. Remove protective cover from TI.
NOTE
All performance checks can be performed with manual vacuum
and pressure pumps. Both the manual pumps and the internal
electric pump (for model 1811H) are capable of producing 25 in. Hg
vacuum and 15 psi pressure. Also, external pressure and
vacuum connections are provided for use of external sources.
c. Position TI controls as listed in (1) through (4) below:
NOTE
Close all ports with caps.
(1) PRESSURE CONTROL and VACUUM CONTROL valves fully closed.
(2) CROSSBLEED CONTROL, PRESSURE VENT, and VACUUM VENT valves
fully closed.
(3) On model 1811H, INTERNAL PUMP switch to OFF.
(4) On model 1811H, connect TI to 115 V ac source.
CAUTION
When using a 115 V ac source, the TI power cord must be
grounded to prevent electrical shock.
d. Pump pressure to 20 psi indication on PRESSURE TANK gage and vacuum to 20 in. Hg
indication on VACUUM TANK gage using manual pumps (or internal electric pump on
model 1811H).
percent of full scale. Close valve and observe airspeed for 1 minute. Airspeed should not
decrease more than 2 knots.
f. Open PRESSURE VENT valve slowly to return airspeed to ambient pressure, then
close.
