Northern Airborne Technology AA21-4xx - Manual (Page 21)

SM34 Rev. 4.00 AA21-400 Cabin PA System Manual
Nov 10, 2003 Page 2-3
ENG-FORM: 800-0106.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.3.5.2 Power On checks
WARNING
The AA21-400 is a high power device, capable of producing
tones at very high volume levels. Ensure that all personnel
are well clear of the aircraft prior to keying the siren or PA.
Failure to adhere to this warning could cause injury to
personnel and/or damage to equipment. DO NOT conduct
the following tests inside an enclosed area (i.e. a hangar.)
a)
Install the Cabin PA system and remote amplifier(s) and speaker(s) as
applicable, and then power up the ship’s systems. Turn on all of the radios and
other accessories required for this system. Check that the POWER ON LED on
the AA21-400 illuminates when the power switch is selected to ON.
b) From the front panel switches, select PA and EXT. Key the siren using the front panel
switch and remote Siren key as described in Section 3.4.4.1. The siren should sound
on the external PA speakers, and the level should be at maximum volume (the VOL
control fully cw). If the siren rate needs adjustment use the corresponding trimpot on
the top of the AA21-400. Refer to section 2.3.6.1 for details.
c) Configure the audio system as required to allow connection of the pilot's mic to
the PA and key the cyclic switch for transmit. The mic audio should be heard on
the PA speakers. Adjust the front panel level control for the desired volume. Set
the front panel switch to RADIO, and check for correct radio operation and note
what volume settings will produce a suitable external paging level. USE CARE
TO AVOID FEEDBACK INTO THE MICROPHONE!
Note: A faint audio signal may be heard at the speaker (even when the system is not
paging) due to the very high gain of this system and stray coupling in the wiring.
It should not be audible in flight.