What is this squeal noise

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evapilotaz

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Ok flying this paticular fbo c172n I key the mike PTT to call up the tower and I get this loud squeal noise. The tower doesn't hear the squeal so it must be happens in the headset voice feedback. It only happens in the air and not on the ground. I fly three different c172n and it happens with this particular airplane only. What could be causing this?
 
A couple of SWAGs

There might be a ground problem in that plane for the PTT.

Or check the hand mike for a short in the cable.
 
Sounds like the PTT needs a quick clean on the contacts. You could also see if someone has a PTT like this you can borrow for a minute and go test it:

If the squeal persists, then you know it's in the comm not the mic.
 
evapilotaz said:
Ok flying this paticular fbo c172n I key the mike PTT to call up the tower and I get this loud squeal noise. The tower doesn't hear the squeal so it must be happens in the headset voice feedback. It only happens in the air and not on the ground. I fly three different c172n and it happens with this particular airplane only. What could be causing this?
Click to expand...
My bet is the external speaker is switched on and you are hearing normal mic/speaker feedback. If using a headset make sure the speaker in the roof panel is turned Off via the audio panel.
 
Squealing when I'm flying is usually coming from the pax :D
Anything over 5 degree banks, passage through an inversion, takeoff, landing, and even the drive to the airport are apparently squeal-worthy :rofl:

Err you might also have a second radio tuned to a nearby frequency and be picking up the bleed-through. Could also be a problem with the sidetone setting on the intercom or other intercom settings as was pointed out.

You can try different headsets and also try the copilot jacks and copilot PTT to narrow it down.
 
Do you have two radios set to listen at the same time on the audio panel? If so the one transmitting can set up a feedback loop if the frequencies are close enough.
 
dottat said:
My bet is the external speaker is switched on and you are hearing normal mic/speaker feedback. If using a headset make sure the speaker in the roof panel is turned Off via the audio panel.
Click to expand...

Yep, there's another potential feedback loop.
 
The switch is set to comm one to transmit. Yes dual comm radios. I could try the co pilots ptt but does that mean I have to be connected to the co pilot jacks? Keep in mind it only happens in the air and not on the ground. I reported to to the FBO owner and he said no one else complains. It has happened twice now renting this airplane
 
evapilotaz said:
The switch is set to comm one to transmit. Yes dual comm radios. I could try the co pilots ptt but does that mean I have to be connected to the co pilot jacks? Keep in mind it only happens in the air and not on the ground. I reported to to the FBO owner and he said no one else complains. It has happened twice now renting this airplane
Click to expand...

Try turning the second radio off. Then try isolating every other potential source of electrical interference, including the transponder, lights, especially strobes and beacons, everything you can turn off, one by one.
 
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I was having this problem with my headset (Lightspeed) and the crapola Garmin audio panel only at certain times. I suspect it has something to do with the sidetone feeding back. It definitely is going through the microphone on my headset as I can stop it by moving the mike. Some odd combination of the headset, radio volume, headset volume control... I never figured it out but it goes away for a long time.
 
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