Installation and Operation Manual. ACP DACS Audio Control Panel

Transcription

1 Installation and Operation Manual ACP DACS Audio Control Panel P A T NORM ISO VOX MIN PRESET PTT ICS ICS TX ISO CALL RX ICS SM81 ISSUE 1.00 Northern Airborne Technology Ltd Kirschner Road Kelowna, BC, Canada. V1Y 4N7 Telephone (250) Facsimile (250) Issued on the authority of Northern Airborne Technology Ltd. Copyright 2009

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3 Table of Contents Section Title Page 1. Description 1.1 Introduction Product Description Design Features Specifications Electrical Specifications Physical Specifications Environmental Specifications Product Approval Installation 2.1 Introduction Unpacking and Inspection Warranty Continued Airworthiness Installation Procedures Warnings Cautions Cabling and Wiring Mounting Legend Installation Custom Designation Cross-Reference List Post Installation Checks Adjustments Accessories Required But Not Supplied Installation Kit Legend Installation Kit Installation Drawings Operation 3.1 Introduction General Information Operational Criteria Controls and Indicators Built-In Tests (BITs) Faceplate Illumination Transceiver Radio Controls Transmit Active Indicator Patient Mode Control VOX Threshold Transmit Selector Switch TX/ICS PTT Switch RX/ICS Volume Control ISO/CALL Button 3-4 Installation and Operation Manual Page iii ENG-FORM: DOT

4 Section Title Page ISO Indicator CALL Indicator Transmit Features Back-up and Emergency Modes 3-6 Installation and Operation Manual Page iv ENG-FORM: DOT

5 Section 1 Description 1.1 Introduction Information in this section consists of product description, design features and specifications for the ACP DACS Audio Control Panel (ACP51). All derivative product information shall be contained in the applicable manual supplement, which may be obtained from Northern Airborne Technology Ltd as required. Review all notes, warnings and cautions. Note: This manual contains information applicable to units s/n 3000 and above. For information applicable to units below s/n 3000 contact the product support department at Northern Airborne Technology Ltd. 1.2 Product Description The ACP51 is an Audio Control Panel from the Northern Airborne Technology Ltd. Digital Audio Communication System (DACS). The DACS is a communications management system that distributes and controls all of the audio in an aircraft. It manages the audio from all transceivers, receivers and audio warning sources. It enables the transmission of microphone audio to a selected transmitter and distributes all Inter-Communication System (ICS) audio. The ACP51 is a Dzus mounted unit that allows the operator to adjust the volume, select a transceiver and select the patient mode. The audio control panel is a terminal that monitors user switch selections and level adjustments, passing them along to the Audio Management Unit (AMU50). It also has several status indicators that illuminate when commanded to do so by the AMU. The ACP51 communicates with the AMU50 over a serial data port. All audio connections are made to the Audio Management Unit where the audio processing is completed. The Audio Management Unit is capable of supporting six Audio Control Panels. The system architecture is set up in a star configuration to prevent loss of the entire system due to the failure of one connection. The Audio Control Panel receives its power from the Audio Management Unit. Receiving power from the AMU along with the serial data wiring decreases the complexity of the wiring in the aircraft and reduces the number of breakers required for the audio system. The ACP51 operates with ACP software loaded into the microcontroller flash memory. 1.3 Design Features The faceplate of the ACP51 incorporates replaceable legends for the transceivers. This enables the installing agency to change the names of the radios on individual units. The ACP has NVIS Green A faceplate backlighting and NVIS Green B annunciators. Section 1 Rev: 1.00 Issue 1 Page 1-1 ENG-FORM: DOT

6 1.4 Specifications Electrical Specifications Input Signals Input Power The ACP requires a conditioned Input Voltage supplied by an external communications management unit such as the AMU50: Nominal: Maximum Current: 25.5 Vdc Vdc Night Mode Input Activation of the Night Mode input places the ACP51 integral lighting into Night Mode. In this state the lighting is dimmed to be suitable for viewing at night. The ACP51 remains in Night Mode for at least 50 ms after the Night Mode input is deactivated. Quantity: one Logic: active LO, switched ground with no external pull up Input Active: 3 Vdc Current Draw: 100 ma Input Protection: diode protected to +45 Vdc maximum NVG Mode Input Activation of the NVG Mode input places the ACP51 integral lighting into NVG Mode. In this state the lighting is dimmed to be suitable for NVG viewing. The ACP51 remains in NVG Mode for at least 50 ms after the NVG Mode input is deactivated. Quantity: one Logic: active LO, switched ground with no external pull up Input Active: 3 Vdc Current Draw: 100 ma Input Protection: diode protected to +45 Vdc maximum Lights Quantity two mutually exclusive panel lighting power inputs Standard Panel Lights: 27.5 Vdc Maximum Current: Vdc Optional Panel Lights: 5 Vdc Maximum Current: Vdc RX Mute Input While the RX (Receive) Mute Input is active, the ACP51 sets the Transceiver Volumes, except for the Transceiver selected by the Transmit Select switch, to their minimum value. Quantity: one Logic: active LO, switched ground, no external pull up Input Active: 3 Vdc Current Draw: 100 ma Input Protection: diode protected to +45 Vdc maximum Section 1 Rev: 1.00 Issue 1 Page 1-2 ENG-FORM: DOT

7 Output Signals ISO Mode When the Patient switch on the front panel of the ACP51 is placed in the NORM position, the ISO Mode output is inactive. When the Patient switch on the front panel of the ACP51 is placed in the ISO position, the ISO Mode output is active (grounded). Quantity: one Logic: active LO, switched ground Output Inactive: Output Active: Current: Bidirectional Signals >10 MΩ 2 Ω 100 ma maximum Communication The ACP51 communicates with an external communications management system such as the AMU50 via one bi-directional RS422 serial data port Physical Specifications Height Depth Width Weight Material and Finish Connectors Installation Mounting mm (2.25 in) maximum mm (2.68 in) maximum behind Dzus rail mm (5.75 in) maximum 0.51 kg (1.12 lbs) maximum Brushed aluminum, conversion coated One 15 pin D-Sub (male), V5 locking hardware RS-422 Cable: 20.0 m (785.9 in) maximum Installation Kit: ACP50-IKC Four Dzus fasteners, 2.89 cm (1.137 in) vertical spacing Environmental Specifications The ACP has been tested to the environmental conditions listed below. Environmental categories for which TSO compliance has been demonstrated are listed on the Environmental Qualification Form in Section 2 of this manual. Temperature -40 to +70 C (operating) -45 and +85 C (short-time operating) -55 to +85 C (ground survival) Altitude 50,000 feet max Humidity 95% non-condensing Shock Operational shock; 6 g for 11 ms Crash safety (impulse); 20 g for 11 ms Crash safety (sustained); 20 g for 3 s Vibration RTCA/DO-160E Section 8 Categories (SBM) (U2FF1) Section 1 Rev: 1.00 Issue 1 Page 1-3 ENG-FORM: DOT

8 1.4.4 Product Approval When installed as part of the Northern Airborne Technology Ltd DACS: FAA: TSO C139 (RTCA/DO-214 Class Ib, RTCA/DO-160E, RTCA/DO-178B Level C) Refer to SM76 AMU Audio Management Unit Installation and Operation manual for further installation compliance details. Section 1 ends Section 1 Rev: 1.00 Issue 1 Page 1-4 ENG-FORM: DOT

9 Section 2 Installation 2.1 Introduction Information in this section consists of unpacking and inspection procedures, installation procedures, postinstallation checks and installation drawings for the ACP DACS Audio Control Panel (ACP51). Review all notes, warnings and cautions. 2.2 Unpacking and Inspection Unpack the equipment carefully and locate the warranty card. Inspect the unit visually for damage due to shipping and report all such claims immediately to the carrier involved. Check that all items listed below are present before proceeding and report any shortage immediately to your supplier: - Warranty Card - Operators Manual - Certificate of Conformity or Release Certification Warranty All Northern Airborne Technology Ltd. products are warranted for 2 years from date of installation by an authorized dealer, to be free of defects in workmanship or performance. This warranty covers all materials and labour, but is exclusive of any transport to deliver the defective unit to and from Northern Airborne Technology Ltd or its designated warranty repair center, or any labour to remove or re-install the defective unit in the aircraft. Contact Northern Airborne Technology Ltd. for any questions regarding this warranty, its applicability to your units and/or for return authorization. Northern Airborne Technology Ltd. is the final arbitrator concerning warranty administration. Units which have been physically damaged, burned, immersed in water or otherwise abused beyond the scope of normal use will not be considered for warranty. WARRANTY IS VOID UNLESS THE PRODUCT IS INSTALLED BY AN AUTHORIZED NORTHERN AIRBORNE TECHNOLOGY LTD DEALER. Product for which a warranty card is not returned shall be warranted from date of manufacture. 2.3 Continued Airworthiness Maintenance of the ACP51 is on condition only. Periodic maintenance of this product is not required. 2.4 Installation Procedures Warnings WARNING: High volume settings can cause hearing damage. Set the headset volume control to the minimum volume setting prior to conducting tests, and slowly increase the headset volume to a comfortable listening level. Section 2 Rev: 1.00 Issue 1 Page 2-1 ENG-FORM: DOT

10 2.4.2 Cautions CAUTION: Do not bundle any lines from this unit with transmitter coax feed lines. Do not bundle any logic, audio, or DC power lines from this unit with 400 Hz synchro wiring or AC power lines. Do not position this unit next to any device with a strong alternating magnetic field such as an inverter, motor or blower, or significant audio interference will result. In all installations, use shielded cable exactly as shown, and ground only as indicated. Significant problems may result from not following these guidelines. Failure to follow the installation and wiring instructions provided in this manual for power and ground connections, including the rating of the circuit breaker, may lead to damage in the power input circuitry of the unit Cabling and Wiring All wire shall be selected in accordance with the original aircraft manufacturer's Maintenance Instructions or AC B Change 1, Paragraphs through Unshielded wire types shall qualify to MIL-W as specified in AC B Change 1, Paragraphs 11-85, 11-86, and listed in Table For shielded wire applications, use Tefzel MIL-C shielded wire with solder sleeves (for shield terminations) to make the most compact and easily terminated interconnect. Follow the connector map in Section 2.7 as required. Allow 3" from the end of the shielded wiring to the shield termination to allow the connector hood to be easily installed. Reference the interconnect drawing in Section 2.7 for shield termination details. Note that the hood is a "clamshell" hood, and is installed after the wiring is complete. Aircraft harnessing shall permit the unit to be lowered from the panel for easy access. Maintain wire segregation and route wiring in accordance with the original aircraft manufacturers Maintenance Instructions. Unless otherwise noted, all wiring shall be a minimum of 22 AWG, except power and ground lines, which shall be a minimum of 20 AWG. Reference the Interconnect drawing for additional specifications. Check that the ground connection is clean and well secured, and that it shares no path with any electrically noisy aircraft accessories such as blowers, turn and bank instruments or similar loads Mounting The ACP51 may be mounted in any orientation. The ACP51 is provided with four Dzus fasteners for rack mounting. No shock or vibration isolators are required. The ACP51 must be mounted to a clean metal surface which is electrically bonded to the aircraft ground plane. The unit is finished with a coating that prevents corrosion. This coating is electrically conductive and should not be removed for electrical bonding. Section 2 Rev: 1.00 Issue 1 Page 2-2 ENG-FORM: DOT

11 2.4.5 Legend Installation Note: The legends for TX channel labelling must be consistent on each ACP5x within a communications management system (i.e. on each aircraft.) Each ACP51 requires a set of legends, either purchased individually (Part no xxxx) or as a legend kit (Part no. ACPLK-xxx). Each kit consists of a number of printed legends and blanks (to suit customer requirements), and each legend comes complete with a black gasket, either attached or loose in the bag. For additional information, see section Legend Gasket When installing the legends for the first time, each legend must be fitted with a black gasket to ensure uniformity of legend lighting. The gasket fits into place on the back of the legend, but is easily dislodged or damaged. Take particular care to ensure that it is properly positioned before snapping the legend fully into place. If a replacement gasket is required, the whole legend must be ordered. If it is necessary to remove or replace a legend, carefully lever the legend away from the faceplate, and insert the new or replacement legend as described above. CAUTION: If the faceplate is damaged in any way during this process, light leakage may occur, which will necessitate returning the unit to the manufacturer for repair or replacement Custom Designation Cross-Reference List A Custom Designation Cross-Reference List is included in Section 2.7. When installed as part of a Northern Airborne Technology Ltd DACS, this form is used to cross-reference the signal designations from the AMU Post Installation Checks Voltage/Resistance Checks Do not attach the ACP51 until the following conditions are met. Check the following: a) Check pin <2> for +28 Vdc OR pin <3> for +5 Vdc relative to ground (selected lights voltage). b) Check pins <9> and <10> for ground (less than 0.5Ω). c) Check pin <11> for lights ground (less than 0.5Ω). d) Check pins <6> <7> and <8> for ground (less than 0.5Ω) when the appropriate switches are closed. Section 2 Rev: 1.00 Issue 1 Page 2-3 ENG-FORM: DOT

12 Power On Checks WARNING: High volume settings can cause hearing damage. Set the headset volume control to the minimum volume setting prior to conducting audio tests, and slowly increase the headset volume to a comfortable listening level. Install the AMU50 or similar audio management unit and power up the aircraft s systems. a) Check pin <1> for ACP51 power (+25 Vdc from AMU50 or similar). Verify normal operation of all functions of the ACP51 and communications management system as described in section 3 of this manual. Upon satisfactory completion of all performance checks, make all required log book entries, electrical load, weight and balance amendments and other documentation as required by your local regulatory agency before releasing the aircraft for service. 2.5 Adjustments There are no adjustments on the ACP Accessories Required But Not Supplied The installation kit and legends necessary to complete the ACP51 installation may be included in the price but MUST be specified and ordered separately. The ACP51 requires a set of legends, either ordered as separate line items, or as a Legend Installation Kit ACPLK\xxx, and an Installation kit ACP50-IKC Installation Kit Installation Kit ACP50-IKC consists of the following: Quantity Description Part # 1 D-min 15 Socket Housing R pin GVL Hood/Lockarm Strain Relief (Set) MS Crimp Socket Legend Installation Kit The contents of each approved Legend Installation Kit ACPLK\xxx can be viewed on the Northern Airborne Technology Ltd website at Each individual legend is specified by a Part Number in the form xxxx, where xxxx represents the text on the legend. For information on non-standard legends, please contact Northern Airborne Technology Ltd. Section 2 Rev: 1.00 Issue 1 Page 2-4 ENG-FORM: DOT

13 2.7 Installation Drawings DOCUMENT REV. DESCRIPTION TYPE SERIAL NO. ACP ACP51\100\ DACS Audio Control Panel Interconnect 3000 and up ACP51\100\ DACS Audio Control Panel Connector Map 3000 and up ACP51\100\ DACS Audio Control Panel Environmental Qual Form 3000 and up ACP51\100\ DACS Audio Control Panel Custom Designation X-Ref List 3000 and up ACP51\100\ DACS Audio Control Panel Mechanical Installation 3000 and up Section 2 ends following the above documents Section 2 Rev: 1.00 Issue 1 Page 2-5 ENG-FORM: DOT

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20 CUSTOM DESIGNATION CROSS-REFERENCE LIST NAT Part No.: ACP Description: ACP DACS Audio Control Panel Document.: ACP51\100\724-1 Rev.: 1.00 Only for use with the NAT DACS AMU This document is used to correlate between the ACP51 controls and the AMU50 Interconnect (AMU50\001\403-0 through 403-5) and Connector Map (AMU50\001\405-0) designations. TRANSCEIVER DESIGNATIONS STANDARD VHF1 VHF2 TAC1 TAC2 TAC3 TAC4 TAC5 PA CUSTOM TX ISO P A T NORM ISO VOX MIN PRESET PTT ICS ICS TX ISO CALL RX ICS CALL End of custom designation cross-reference list Rev Page 1 of 1 ENG-FORM: DOT Jun 02, 2009

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22 Section 3 Operation 3.1 Introduction Information in this section consists of the functional and operational procedures for the ACP DACS Audio Control Panel (ACP51). The ACP51 is an Audio Control Panel for a communications management system such as the Northern Airborne Technology Ltd Digital Audio Control System (DACS). The faceplate of the ACP51 supports replaceable legends for the transceivers. This enables the installing agency to change the names of the radio controls to match the radios installed on the aircraft. The illumination of the ACP51 faceplate is linked to the aircraft dimming buss, and any increases or decreases in illumination will be relative to the selected lighting mode. The ACP has NVIS Green A faceplate backlighting and NVIS Green B annunciators. 3.2 General Information The ACP51 is part of a communications management system (such as the Northern Airborne Technology Ltd DACS) that distributes and controls all the audio in an aircraft Operational Criteria It is important to be aware that each unit may have different functions depending on how the system has been configured during installation. Normally the pilot and copilot will be designated User 1 and User 2 respectively. Note: Confirm the specific criteria associated with this installation with your installing agency. 3.3 Controls and Indicators Built-In Tests (BITs) Note: For visual confirmation of the following tests, the system must be in the NORM mode, and the Transmit selector switch must be set to select a transceiver (i.e. in any position other than ICS) Power-Up Built-In Test (PBIT) On power-up, the ACP51 runs a PBIT to confirm correct operation of the unit. When power is first applied, all indicators will illuminate for a period of approximately 3 seconds. If the ACP51 has not established connection to other units in the communications management system three seconds after the power is applied, the ACP51 indicators will extinguish until connection is achieved. Section 3 Rev: 1.00 Issue 1 Page 3-1 ENG-FORM: DOT

23 Continuous Built-In Test (CBIT) The ACP51 requires serial communication with the communications management system (for example the Northern Airborne Technology Ltd AMU50). If serial communications is lost for more than 0.5 seconds, all the ACP51 indicators will extinguish and remain off until communication is re-established Faceplate Illumination P A T NORM ISO VOX MIN PRESET PTT ICS ICS TX ISO CALL RX ICS ACP faceplate with blank legends. The illumination of the ACP51 faceplate is linked to the aircraft dimming buss. When backlighting is off, there is no faceplate illumination other than Transmit Access indicators (see section 3.3.3). When backlighting is on, all knobs and legends illuminate to a level proportional to the aircraft dimming buss level Transceiver Radio Controls Control Legend Transmit Access Indicator The ACP51 has eight Transceiver Receive audio volume controls with interchangeable illuminated legends to allow selection of suitable identification. Each control is an illuminated rotary knob that is used to control the volume for a specific transceiver. Rotating the knob clockwise (cw) increases the volume, and counterclockwise (ccw) decreases the volume. The master RX Volume control can be used to effect a global adjustment to all Transceiver volume levels (see 3.3.9). Each control has a push-on/push-off action to allow individual selection of the required transceivers. In the on position, the control knob is extended, the volume for the associated transceiver can be adjusted by rotating the knob, and if backlighting is on, the illumination of the triangular arrow will be at maximum. In the off position, the knob is retracted (pressed in), the volume is selected to the minimum value (off), and if backlighting is on, the arrow illumination is minimized or off. Section 3 Rev: 1.00 Issue 1 Page 3-2 ENG-FORM: DOT

24 Above each control knob is a Transmit Access indicator, which illuminates green when the associated transceiver is selected (by the transmit selector) and the ACP51 has access to that transceiver. If access to that specific transceiver has been restricted at installation, the indicator remains dark Transmit Active Indicator TX The ACP51 has a dead-front TX indicator that illuminates when the unit is transmitting on any transceiver Patient Mode Control P A T NORM ISO Note: The Patient Mode Control is a two-position locking toggle switch that can be used by the ACP51 user to select the patient headset mode - NORM (normal) and ISO (Isolation). The locking mechanism prevents accidental de-selection of the currently selected mode. It is important to be aware of the configuration set-up for your installation. Confirm the specific criteria associated with this installation with your installing agency VOX Threshold MIN VOX The VOX control is a rotary control used to select the VOX threshold of the unit. When the control is rotated full cw, the threshold is at maximum, and when rotated fully ccw to the detent, the threshold is at minimum. When rotated ccw into the detent, the ACP51 is in the PRESET position. PRESET PTT PRESET When the VOX pot is set fully ccw into the detent, the intercom audio will be in the PRESET VOX position. The preset threshold is selected at installation. MIN (Hot Mic Operation) When the VOX pot is set fully ccw to the MIN position, the intercom audio will be easily activated. (Take care not to rotate the control into the detent position to the PRESET position.) PTT (Keyed ICS Operation) Keyed ICS is activated when switched by an ICS PTT switch. VOX (Voice Activated) Set the VOX control fully ccw and then slowly rotate cw just to the point where no intercom audio can be heard. This setting will vary with ambient noise conditions, and the quality and number of microphones connected in the system. Section 3 Rev: 1.00 Issue 1 Page 3-3 ENG-FORM: DOT

25 3.3.7 Transmit Selector Switch The Transmit (TX) Selector is a nine position rotary switch used to select the transceiver for transmission. For additional information see section PTT ICS When the TX Selector switch is turned fully ccw, it will be aligned with the ICS position. Each of the other positions will align with one of the selectable transceivers TX/ICS PTT Switch ICS TX The TX/ICS PTT switch is a momentary centre-off toggle switch, labelled ICS and TX. When the ICS/TX switch is held in the ICS position, the ACP51 will key the ICS for all users assigned to the ACP. When the ICS/TX switch is held in the TX position, the ACP51 will key the transceiver selected by the TX selector switch, and will route the audio from the microphones of all users assigned to the ACP to the transceiver RX/ICS Volume Control RX ICS The master RX/ICS Volume control is a dual concentric knob. The upper (inner) knob controls the ICS volume potentiometer, and the lower (outer) knob controls the master receive volume for the unit. Rotating the ICS knob cw will increase the ICS volume, and ccw will decrease the volume. The master RX pot affects all Transceiver receive volumes. All receive volumes are reduced by 75% when it is rotated fully ccw, and increased proportionally as it is rotated cw. When rotated fully cw, the master RX volume is set to maximum ISO/CALL Button The ISO/CALL button is a momentary push-button switch that can be used to enter ISO mode (Crew only), or to call the crew when in isolation (ISO) mode. ISO CALL Isolation means that the normal intercom audio communications path is temporarily suspended. Isolation has no effect on any other audio source Crew/Passenger Talk Groups Note: Confirm the specific criteria associated with this installation with your installing agency. The communications management system provides the ability to decide which ACPs will be designated as crew during ISO. Typically, up to three ACPs can be designated as crew (i.e. the users assigned to those ACPs are members of the crew talk group) - all others are designated as passenger. Members of the crew talk group can use the ISO/CALL button located on their Audio Control Panel to initiate and cancel the talk group selection (ISO mode). On the passenger Audio Control Panels, the same button acts as a CALL button. Section 3 Rev: 1.00 Issue 1 Page 3-4 ENG-FORM: DOT

26 ISO/CALL Button Operation The way the ISO/CALL button functions is set up at installation and depends upon the communications management system, such as the DACS. In a DACS, only the crew-designated ACPs can be used to select ISO mode. On all non-crew (passenger) ACPs, the ISO/CALL button will act as a CALL button only. Members of the crew talk group are isolated from the remainder of the aircraft (passengers) when the ISO/CALL button is pressed on a crew ACP. When ISO mode is active, all ISO indicators on all ACPs will illuminate, as will any external isolation indicator. The crew talk group can communicate normally, and the passengers can communicate amongst themselves but the two groups will not hear each other. When the ISO/CALL button is pressed on a non-crew ACP and ISO mode is active, it operates as a CALL button; the CALL LED will flash on all ACPs, and a chime will sound in all headsets. When the ISO/CALL button is pressed on a non-crew ACP and ISO mode is not active the button has no function. To end ISO mode, press the ISO/CALL button again on one of the crew ACPs; the CALL and ISO indicators extinguish and the chime function is deactivated ISO Indicator ISO The ACP51 has a dead-front ISO indicator that will illuminate when Isolation mode has been selected CALL Indicator CALL The ACP51 has a dead-front CALL indicator that flashes to signify that another user is calling when the system is in ISO mode. The CALL Indicator will flash once per second for a Normal call and at 3 times per second for a High Priority call Call Priority When the ISO mode is selected by the crew, a passenger may use the ISO/CALL button on their ACP51 (or an external remote switch) to contact the crew. The ISO/CALL button on each passenger ACP51 can be designated either a Normal Call, High Priority Call, or Isolation Override at installation. Any remote switch will be wired to have a preset priority status. If the switch is designated a Normal or High Priority call, a call will be indicated in the crew unit(s) along with a call tone in all users phones. The crew can then cancel ISO mode to acknowledge the call; or if the call is not answered it can either continue, or be set at installation to time out. If the ISO/CALL button is designated with an Isolation Override functionality, the Isolation Mode is temporarily suspended and the passengers can communicate with the crew members. Section 3 Rev: 1.00 Issue 1 Page 3-5 ENG-FORM: DOT

27 Transmit Features Note: Confirm the specific criteria associated with this installation with your installing agency. Various features may be configured through the audio management unit during installation. Typical examples are given below User Priority The DACS is designed so that if a user has keyed a specific transceiver, no other user can access that transceiver for the duration of the transmission Transmit Time-Out The DACS has a stuck microphone (transmit key-line shorted to ground) timeout feature. After thirty to one hundred and twenty seconds (adjustable at installation), the transmit key input signal is overridden, the selected radio will stop transmitting, and the transmit indicator on the user s Audio Control Panel will no longer be displayed. The timer is reset once the transmit key-line is no longer grounded. At installation, this feature may be disabled Back-up and Emergency Modes When the communications management system is operating in Back-up or Emergency mode, the ACP51 and all associated headsets are disabled. Any appropriate installed external indicator(s) will illuminate to warn users that emergency (or back-up) mode has been activated. Section 3 ends Section 3 Rev: 1.00 Issue 1 Page 3-6 ENG-FORM: DOT