continuous beep when master switched on

I just recently purchased a 2010 RV-12 with the D180. I really love to fly it. I am currently in transition training for insurance and things have been going well until the last flight. When I turn on the Master, a continuous beep can be heard through the headset. It is about half the volume of any alerts from the D180. It never went away for the duration of the last flight. Only turning the master off stops it. Has anyone had this happen to them? Is it a loose ground? Not sure where to start. Any feedback would be greatly appreciated.

Thank you, Lee

Stall horn wired wrong or faulting?

Advwall44 said:

When I turn on the Master, a continuous beep can be heard through the headset. Not sure where to start. Any feedback would be greatly appreciated.
Thank you, Lee

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After turning on the Master, I would start pulling fuses or breakers to isolate which circuit is causing the beep. Hopefully you have a wiring diagram to refer to after that.

With only the master? Or with strobes or pulsing landing light on also?

It is a continuous tone. It comes on immediately when the master switch is turned on. Nothing else is on yet.

I am going to look into the stall horn tab being bent or jammed from my pre-flight, possibly.

I’ve had that happen twice, once during an avionics install and once in the air. In both cases it was the stall warning switch. In the first case the technician had rubbed against the vane. New switch required. The second occurred during turbulence on final and continued until shutdown. Ordered a new switch and then found on the next flight that it had righted itself and has been fine ever since.

Thanks for all your input. I will get to it in the next couple days and let you know what I find out.

What kind of ELT do you have? The ACK 406 ELT beeps when you turn on power to it (usually through your master switch). If it continues to beep, the cadence of the beeps, with a slight pause between the sequence, will indicate what the fault is. If you have this ELT, and it sounds like there is a certain cadence to the beeps, removing power from the ELT will tell you - pull the CB or fuse feeding a very small current, 40 ma, so .5 - 1 amp maybe, and that could possibly silence the beeps and alert you to a fault in your ELT.

If you have this ACK ELT: You will get one beep OR a second beep after a 2 second delay, if everything is normal. Silence after that.
If there is a fault, you will get 2-5 quick beeps with a 2 second pause before this sequence repeats. The number of beeps indicates what the fault. For instance, if you get 2 quick beeps, a 2 second pause, then 2 more quick beeps, and this just keeps repeating, you have a low internal ELT battery.

Just another thing to check if you have this ELT.

We had that on both 12's and it related to poor isolation of the music input jack socket. The guy at PS Engineering steered us that way.

I had a loud feed back tone and found it was the volume was maxed out on the intercom panel....

Search back through previous RV12 posts or Avionics, there are good replies there.

It was the stall warning. Easy adjustment to the stall warning tab and good to go. Thanks for the info. Happy flying and be safe.

Good call. It was the stall horn. Thanks