Strange VHF/ACP Malfunction A320

[Flo121142]

Hi guys,

yesterday night I experienced a strange malfunction on an A320. During the cockpit preperation we got a CALL light on the VHF1 key on all ACP and the buzzer (like when you get a SELCAL or cabin call). This could be reset (by the RESET button on the ACP) but reoccured several times over the next minutes. After many unsucessfull resets of the related systems, a full electric power down and restart and a rerack of some box done by the engineer maintenance swaped a box in the avionic bay, which apparently solved the problem. The aircraft was fresh out of the paintshop and this was the ferry flight over to our main base to get it back into service. Did anybody else ever experience something like that? Neither me nor the captain have ever seen that kind of behaviour on an A320 - I never saw the CALL light lit up on the VHF key, I wonder if there is any system that could cause this (after all there is no SELCAL or similar system available for VHF to my knowledge)?
The problem occured even on Batteries only (during the full power down) on ACP1...the VHF1 radio was working fine during that time (did several radio checks during the trouble shooting).

[QA1]

Most likely a problem with the Audio Management Unit (AMU).

The AMU controls the switching and interface between the different comms systems, including ACP’s, RMP’s, headsets etc.

One of the inputs to the AMU is the selcal code selector, which gives the aircraft its selcal identity.

From the sound of it, the AMU thought you had received a selcal on VHF.
Re-racking the box most likely fixed it. :confused:

[ahramin]

(after all there is no SELCAL or similar system available for VHF to my knowledge)
VHF SELCAL works exactly the same way as HF SELCAL. Same aural tone, same visual signal on the ACP, same SELCAL code. What you had was a faulty SELCAL.

[Fursty Ferret]

I've seen this happen before, but in flight and twice in the same place (outbound, return). Faulty SELCAL unit. They're fairly sensitive, have to pick it up on the aural catastrophe that is HF.

[FlightDetent]

I second what ahramin wrote. Some time ago, LHR ATIS would induce fake SELCAL on the fleet I used to fly.

cheers, FD.