TB 9-4920-457-35
b. Adjustments
(1) Loosen locking screw, located left of barometric adjustment knob (screw may be
covered with black paper dot).
(2) With pneumatic pressure standard indicating 0 ft altitude, adjust barometric
adjustment knob until altimeter indicates 0 ft altitude.
(3) Pull adjustment knob out and adjust barometric indicator to 29.92 (1013.3 mb).
Push knob down.
NOTE
It may be necessary to repeat (2) and (3) above until no further
adjustments are required.
(4) Tighten locking screw and replace black paper dot (R).
9. Vertical Speed Indicator
a. Performance Check
(1) Press RESET pushbutton on pneumatic pressure standard.
(2) Adjust TI vertical speed zero adjustment screw for 0 indication.
(3) Verify that PRESSURE CONTROL and VACUUM CONTROL valves are closed.
NOTE
As the vertical speed indicator case pressure equalizes with the
static system, the indicated rate will begin to decrease.
Continue to open VERTICAL SPEED control slowly until
indicator indicates 0, then open fully.
(4) Observe vertical speed indicator and slowly open VERTICAL SPEED control
valve. Do not exceed full scale indication on vertical speed indicator.
(5) Slowly adjust VACUUM CONTROL until vertical speed indicator indicates 500 ft
per minute.
(6) When altimeter indicates (passes) 2000 ft, press RATE OF CLIMB pushbutton
on pneumatic pressure standard. After 1 minute, light will stop flashing. Record indication
on pneumatic pressure standard.
(7) Slowly open VACUUM VENT valve until altimeter indicates less than 2000 ft,
then close.
