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Date: Tue, 27 May 2014 07:51:55 -0400
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From: Danny <danny@n107sd.com>
Subject: Audio squeal
Organization: N107SD, Inc.
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This is for all you avionics buffs.  I was headed out for an instrument 
proficiency check last Saturday.  As we were taxiing out I noticed what 
sounded like a slight echo in my headset.  My CFII heard it too.  It was 
the kind of thing one hears from a feedback loop on public address 
microphone.  We didn’t give it much thought at first but as we continued 
talking it got progressively worse until finally it became a squeal 
whenever we spoke, again, just like a PA system microphone.  We played 
with the squelch, volume, and different headsets, all to no avail.  I 
later found that it isn’t there with only the pilot headset plugged in.  
It also disappears when I bypass the audio panel.  This happened once 
before several months ago.  I had it look at by a reputable avionics 
shop but they were unable to replicate it and could find nothing wrong 
with neither my radios nor my audio panel.  I plan to have them take 
another look as soon as they can schedule me in but thought I’d query 
the list in the event anybody here has any experience in this area.  
Your comments, thoughts, and consideration are appreciated.

Danny
LNC2-360 Mk-II
AOPA 04856278
EAA 647062
NRA 156453324
Nothing is foolproof to the sufficiently talented fool.