Northern Airborne Technology AMS42 - Manual (Page 60)

AMS42/44 Dual Channel Audio Controller Manual SM19 Rev. 4.00
Page 3-6 Nov 21, 2003
ENG-FORM: 806-0102.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
3.6 AMS42 Mode Control
The Mode Control switch is a three-position, locking toggle switch that is used to select
between ISO, EMER OPER, and NORM. It is identified with a red cap.
Mode Control Switch
3.6.1 Emergency Operation
The center (EMER OPER) position of the mode switch places the controller into the
emergency operation mode. When switched to the EMER OPER position, both pilot and
copilot controls are removed from the ICS bus and connected directly to their respective
radios. This mode should be selected in the event of a box fault or power failure.
The Emergency function should be tested prior to flight to assure proper operation and
allow the radio levels to be set adequately for emergency operation.
3.6.1.1 Emergency Mode Effects
In the EMER mode, all functions are retained by the pilot and copilot, except ICS and
possibly boom mic operation. If the box or airframe fault prevents the TX annunciator
from lighting during transmit (indicating a failure in the mic keying circuit), then the hand
mic should be used. A power fault of any kind will prevent the TX annunciator from
lighting, giving an immediate indication of failure. If ICS audio is still available, then the
power to the controller has not failed and loss of the TX light indicates TX switch failure.
Note that in the EMER mode, all switches work exactly as they do during NORM operation,
except for the RX and ICS volume controls which will have no effect. Any selected receive
audio is switched to the appropriate user in the ‘emergency’ mode (red mode switch in the
EMER position), but not to any passengers in the system. Level will be lower than NORM
operation because the signals are obtained directly from the radios, bypassing the electronics in
the controller. This is provided for failure situations which make operation impossible in the
NORM mode (i.e., loss of power or amplifier failure, etc.)
3.6.2 Isolation Operation
The mode switch can select an ISO function, which prevents the selected user from
receiving ICS audio. This is useful when passengers are interfering with critical flight
operations (landing, etc.). It can be preselected at installation to isolate the left or right
side. Intercom operation for the passengers and copilot is not affected. It is normally set
for isolation of the right side when the unit is shipped from the factory.