Engineering
Specification
Title:
Vertical
Speed
Indicator,
Ground
Support
Equipment
Barfield,
Inc
4101
NW
29
Street
Miami
Florida
33142
Drawing
No:
23
‐
337
‐
00025
Page
3
of
4
5.4
Friction:
A test shall be performed to ascertain friction. In the time intervals at which the lag
time is measured, the pointer shall move smoothly towards zero (while no vibration is
applied) and shall return to zero within 300 feet
5.5
Leak:
With a vacuum of 15 inches of mercury applied to the static pressure connection, the
leakage shall not cause more than 0.05 inches of mercury pressure drop during a 1
minute period. With a pressure of 10 inches of mercury applied to the static
connection, the leakage shall not cause more than 0.05 inches of mercury pressure
drop during a 1 minute period.
5.6
Position
Error:
With atmospheric pressure applied to the instrument, the difference between pointer
indication when the instrument is in horizontal (Face UP) operating position and
when it is in any other position shall not exceed 50 feet per minute.
6. Qualification
Tests:
All instruments shall comply with the requirements of this section.
6.1
Vibration:
The instrument shall be subjected to vibration during testing. While the instrument is
being vibrated, the drift of the pointer shall not exceed 50 feet per minute and it shall
not oscillate more than 50 feet per minute.