T-34C AIRCRAFT SYSTEMS FAMILIARIZATION
The directional gyro, located in the avionics compartment, is powered by 115 VAC and provides
stabilization of the magnetic heading signal received by the slaving accessory from the flux
A red triangular failure flag will appear on the RMI whenever the RMI is not providing accurate
heading information, when manually slaving, or when no electrical power is available.
Slaving Accessory Operation
The slaving accessory computes the error, which exists between the flux detector heading and
directional gyro and sends a correction signal which aligns the directional gyro with the flux
detector. This process, called slaving, then sends an accurate, gyro-stabilized, magnetic heading
signal to both RMI compass cards. A fast slave mode is initiated the moment electrical power is
applied in order to rapidly align the directional gyro/compass cards with the flux detector.
Accurate gyro compass system operation requires 28 VDC, 26 VAC, 115 VAC and the avionics
master switch ON.
Compass switches are located on the lower left portion of both instrument panels and are used to
manually fast slave the RMI compass card or to disconnect the flux detector if it becomes
unreliable. Compass switches in the respective cockpits are operative only when possessing
avionics command. The switch on the left side of the panel is the compass slave switch and the
one on the right side is the slave left-right switch.
Compass Slave Switch
The compass slave switch is a three-position switch labeled FAST SLAVE, SLAVE and DG.
The SLAVE position is the center position which allows normal operation. Heading information
from the flux detector is stabilized by the directional gyro through the slaving accessory,
resulting in accurate heading information on the RMI. The FAST SLAVE position is a
momentary, spring-loaded (must be held up) position and is used to correct for gyro error
(precession) which might be induced by aerobatic flight. This position rapidly aligns both
compass cards and the directional gyro to the flux detector. To effect alignment, hold the
compass slave switch up until the compass cards stop rotating (Note: The failure flag will drop
into view while fast slaving.) Fast slaving should only be accomplished with the aircraft in an
unaccelerated level flight attitude. The DG position (free gyro mode) will occur when the switch
is in the down position (not spring-loaded). This disables automatic slaving and enables manual
slaving of the RMI. This position is used when the flux detector becomes inaccurate. It
activates the SLAVE LEFT-RIGHT switch, which allows the pilot to turn the directional gyro
and compass cards left or right for proper alignment.
12-4 GYRO AND STANDBY COMPASS SYSTEMS