AUDIO CONTROL PANEL

Question 1

TRANSMITTER SELECTOR & RECEIVER SELECTOR Switches

Answer 1

Transmitter Selector Switches.

• Illuminated: related switch is active
• PUSH -
  
  • only one select switch at a time - pushing a second will deselect the first
  • reception on the ‘transmit’ radio is active regardless of whether related receiver switch is on
    
    • i.e. if you push the transmit selector - you will hear that radio even if not selected on receiver
• can come from hand mic, O2 mask mic, or boom mic
• if you use boom mike or hand mic - volume is decreased to cockpit speakers
• Unique selections:
  
  • FLT: connection to the FLT INTERPHONE jack at the external pwr receptacle and any other ACP
  • SVC: provides comm between cockpit, FA and Ground handlers. External jacks can be added to the system by selecting the Service Interphone Switch on the AFT Overhead Panel
  • PA: can make announcments from the flt deck using the related ACP OR the PA handset (rear pedestal) which bypasses the ACPs. PA use is prioritized with cockpit having first priority.

Receiver Switches.

• Illuminated (white): related switch is active
• Rotate - adjusts volume
• Push - allows reception of selected comm or nav (multiple switches may be selected)
• Push Again - DESELECTS related comm or nav unit

Question 2

PUSH TO TALK Switch

Answer 2

R/T:

• spring-loaded to neutral
• Radio - Transmit
• keys O2 mask OR boom mic for transmission as selected by transmitter selector

I/C:

• Intercom
• keys O2 mask OR boom mic for direct transmission over FLIGHT INTERPHONE and bypasses transmitter selector

** Can also use switch on pilot yoke (lower - I/C : upper - R/T)

Question 3

MASK-BOOM Switch

Answer 3

MASK: selects O2 mask mic for transmission

BOOM: selects boom mic for transmission

* if the switch is removed - the mic AUTO SWITCHES to mask when mask regulator is pressurized.

Question 4

FILTER Switch

Answer 4

V:

• Voice
• receive NAV and ADF voice audio

B:

• Both
• receive NAV and ADF voice AND range audio

R:

• Range
• receive NAV and ADF station ID range (code) audio

Question 5

ALT-NORM Switch

Answer 5

NORM:

• Normal
• ACP operates normally

ALT:

• alternate
• ACP operates in DEGRADED mode
• flight interphone system is in the emergency mode
• in this selection only the following switches work:
  
  • BOOM-MASK
  • R/T (this position only of the PTT switch)
• only the mask and boom mics can be used on the usable radio
• ALT (Capt or observer ACP) - you hear audio from VHF 1 - when you key the mic, the audio and PTT signals go to VHF 1
• ALT (FO ACP) - hear audio from VHF 2 - when you key mic it goes thru VHF 2

INOP ITEMS IN DEGRADED MODE:

• mic & receiver selectors
• speaker and speaker switch
• hand mic
• pa and interphone from respective ACP
• svc interphone and the INT switch on the control wheel PTT
• audio warnings for alt alert, GPWS and windshear are not heard on an audio system operating in degraded mode
• headset volume is PRESET

Question 6

SPEAKER Switch

Answer 6

Illuminated (white): SPKR switch is active

• PUSH - audio from selected receiver is heard on overhead speaker
• ROTATE - adjust overhead speaker volume
• PUSH AGAIN - deselects audio to speaker