Change 3 2-77
Figure 2-33. Pitot and Static System
(7) Attitude scale. Used in conjunction with alti-
tude indicator needle to indicate aircraft altitude in
hundreds of feet. Subdivided into 20 foot increments.
If the altimeter does not read within 70 feet of
field elevation, when the correct local barometric
setting is used, the altimeter needs calibration or
internal failure has occurred. An error of greater
than 70 feet also nullifies use of the altimeter for
2-83. STANDBY ATTITUDE INDICATOR.
An air-driven standby attitude indicator is located on
the pilots instrument panel (fig. 2-16).
a. Standby Attitude Indicator Controls, Indicators,
(1) Bank angle scale and pointer. The moveable
bank angle pointer indicates aircraft bank angle by mov-
ing around a fixed bank angle scale.
(2) Pitch angle scale. Aircraft pitch angle may be
read under the symbolic miniature aircraft on a vertical
pitch angle scale located on the attitude sphere.
(3) Horizon bar. The horizon bar displays aircraft
pitch and roll attitude with respect to the earths horizon.
(4) Pitch adjustment knob. This knob is used to
vertically adjust the symbolic miniature aircraft for
changes in the aircrafts level flight pitch attitude.
(5) Symbolic miniature aircraft. Aircraft pitch and
roll attitudes are displayed by the relationship between
the fixed miniature aircraft symbol and the movable atti-
(6) Eyelid display. The eyelid display surrounds
the attitude sphere to provide a positive attitude identifi-
cation. When the aircraft is in an upright position the
upper (blue) eyelid is located next to the upper (blue) half
of the attitude sphere, while the lower (brown) eyelid
display is located next to the lower (brown) half of the
attitude sphere. Thus the eyelid display maintains the
proper ground-sky relationship, regardless of the posi-
tion of the sphere, to aid in recovery from unusual atti-
2-84. VERTICAL SPEED INDICATORS.