(1) T3 ANG. The standby attitude indicator,
located below the TCAS II display, Figure 3B-13, is
powered by engine bleed air and provides a visual
reference of the aircraft pitch and roll. The attitude
indicator is comprised of a self-contained gyro to erect
the sphere providing the pitch and roll reference, an
indicating symbol representing the aircraft, and a
horizontal line behind the indicating symbol that
represents the horizon. The moveable indicating
symbol may be adjusted vertically to correct for
variations in level flight attitudes by a small knob
located on the front base of the indicator.
(2) T3 OSA . The standby attitude reference
system, comprised of the attitude indicator located on
the extreme left center of the pilot's instrument panel
and a 28 Vdc emergency power supply, provide a
visual indication of the aircraft flight attitude. The
attitude reference system is designed to provide a
standby attitude indicator that is powered by a source
independent of the aircraft electrical generating
system. The system will provide reliable attitude
information for at least 30 minutes after a total failure
of the aircraft electrical system.
The power supply contains sealed lead-acid
batteries with a rating of 5.0 ampere hours. During
normal operation, the aircraft 28 Vdc system supplies
power to the indicator and power supply batteries. In
the event aircraft electrical power fails, the power
supply will take over the duties of powering the attitude
The attitude indicator is a 28 Vdc powered,
electrically driven gyro and contains an inverter circuit
board for converting the 28 Vdc input to 22 Vac 400
Hz for indicator operation. The power warning flag is
rotated out of sight by a flag motor that allows the flag
to display if one or more phases of power are
interrupted. The flag motor also allows the flag to
display if the PULL TO CAGE knob is in the caged
position. The rotor speed and the mechanical erection
system enable the indicator to provide a minimum of 9
minutes of useful attitude information after complete
electrical power interruption.
b. Controls and Indexes.
(1) Standby Attitude Reference Indicator
Controls and Indexes T3 ANG . Refer to Figure
(a) Attitude Sphere. Contains gyro and
reference lines for pitch and roll degrees.
(b) Roll Index. Rotates with aircraft to
provide measurement of angular displacement by the
(c) Roll Pointer. Indicates vertical in any
(d) Horizon Line. Indicates earth horizon
relative to aircraft pitch attitude.
(e) Pitch Knob. Rotated to adjust the
displacement of miniature aircraft.
aircraft nose and wings. Indicates pitch and roll
attitude relative to the horizon. Adjustable through
pitch knob for varying pitch attitudes.
1. Attitude Sphere
2. Roll Index
3. Roll Pointer
4. Horizon Line
5. Pitch Knob
6. Pitch Scale
7. Symbolic Miniature Aircraft
Figure 3B-13. Standby Attitude Reference
Indicator T3 ANG