Right headphone FAILS Only at High Speeds

[flysolow]

Hello, we have a new issue that I’m hoping someone has seen before and has solved. Our passenger headsets developed a crackle and popping sound, to a level above annoyance and almost to unbearable. The sound is only in the passenger headsets jacks, both traditional and lemo. The sound seems to be only while talking on the intercom. Most importantly, the crackle and pop ONLY happens at speeds greater than 150kts. Furthermore, the noise is only in the right ear of both rear passenger headset jacks. The noise gets to such a high level where we loose the right channel all together. As soon as we slow to under 150(ish)kts, the right channel comes back on with light crackle and pop sounds.
 

The aircraft is a late model M20R that was 100% gutted and rewired per the Garmin STC instruction manuals. The aircraft is equipped with a G500 TXi, GTN 750 Xi, 650 Xi, GMA 35c, duel GI 275’s, GTX345R, GFC500, etc. While flying above 150kts, and experiencing the cracking sound, we have tried multiple Bose headsets in both traditional and powered lemo jacks. We have tried pulling circuit breakers to see if another device was causing the disturbance and no luck. There are no problems at full power on climb, or any other time other than at over 150kts.
 

Anyone have ideas? 

[ArtVandelay]

Try closing the footwell vents. I can imagine the air could be causing a poor connection to be breaking or shorting out. Visually check headset connections under the panel.

[flysolow]

5 hours ago, ArtVandelay said:

Try closing the footwell vents. I can imagine the air could be causing a poor connection to be breaking or shorting out. Visually check headset connections under the panel.

Thanks ArtVandelay! Great idea! That was one of ours too. We tried closing the vent to see if the airflow was diverted around the black putty and down the sidewall and no luck either. There was no change with the vent open or closed. We are going to swap the audio panel and then pull the interior to check the wiring and connections. 

[Pinecone]

Do you mean right seat pax or rear seat?  Or all?

My 252 rear pax jacks are in the overhead panel.  With that, I would suspect something moving around to the air ducts/vents above the head liner.

[LANCECASPER]

7 hours ago, Pinecone said:

Do you mean right seat pax or rear seat?  Or all?

My 252 rear pax jacks are in the overhead panel.  With that, I would suspect something moving around to the air ducts/vents above the head liner.

252s came with only front headset jacks, and no intercom*, so when they added the intercom and rear seat jacks the location would have been left up to the owner or the installer.

Every Ovation came with rear seat jacks in the armrest area.

 

@flysolow The only idea I have is one you've already thought of: get it back into the shop that did the install and have them trouble shoot it.

 

* point #8 on page 46 of this article (https://aeroresourcesinc.com/uploads/198712-1987 Mooney M20K 252.pdf)

[flysolow]

5 hours ago, LANCECASPER said:

252s came with only front headset jacks, and no intercom*, so when they added the intercom and rear seat jacks the location would have been left up to the owner or the installer.

Every Ovation came with rear seat jacks in the armrest area.

 

@flysolow The only idea I have is one you've already thought of: get it back into the shop that did the install and have them trouble shoot it.

 

* point #8 on page 46 of this article (https://aeroresourcesinc.com/uploads/198712-1987 Mooney M20K 252.pdf)

Thanks all! We will continue to troubleshoot and report our findings.

[Pinecone]

18 hours ago, LANCECASPER said:

252s came with only front headset jacks, and no intercom*, so when they added the intercom and rear seat jacks the location would have been left up to the owner or the installer.

Every Ovation came with rear seat jacks in the armrest area.

 

@flysolow The only idea I have is one you've already thought of: get it back into the shop that did the install and have them trouble shoot it.

 

* point #8 on page 46 of this article (https://aeroresourcesinc.com/uploads/198712-1987 Mooney M20K 252.pdf)

Interesting, thanks.

WHY would they come without an intercom and rear seat jacks????

 

[Bolter]

4 minutes ago, Pinecone said:

Interesting, thanks.

WHY would they come without an intercom and rear seat jacks????

 

I assume a cost savings at the factory, or a chance to add another up-charge item with the sale.  I was shocked when I bought my 83 J in 2011, it still was without rear jacks.  Almost 30 years old, and never upgraded.  I had that done before I even picked it up, along with some other items related to the purchase.

[Ragsf15e]

I’m guessing we all remember flying around in clapped out -172s completely without headphones?  I probably have 300+ hours in various pistons without intercoms or headphones between flying with my dad and my own training in the late 80 / early 90s.  Obviously they should’ve been upgraded since then, but it wasn’t all that surprising to see airplanes with a speaker and hand mike in the 80s.  Between the airplanes and being very close to a 5” gun on a destroyer in Vietnam, my dad wears two hearing aids…

[dzeleski]

14 hours ago, flysolow said:

Thanks all! We will continue to troubleshoot and report our findings.

This happened in my J. The jacks were touching the skin of the airplane. Assuming the jacks are like mine and perpendicular (ish) to the skin of the airplane, throw some electrical tape behind the jacks on the skin. Put the panels back on and see if it happens again.

Edited June 5, 2024 by dzeleski

[LANCECASPER]

5 hours ago, Ragsf15e said:

I’m guessing we all remember flying around in clapped out -172s completely without headphones?  I probably have 300+ hours in various pistons without intercoms or headphones between flying with my dad and my own training in the late 80 / early 90s.  Obviously they should’ve been upgraded since then, but it wasn’t all that surprising to see airplanes with a speaker and hand mike in the 80s.  Between the airplanes and being very close to a 5” gun on a destroyer in Vietnam, my dad wears two hearing aids…

I started taking lessons in June of 1985 and didn’t own a headset. I’ve never had exceptional hearing and sometimes it was hard to understand what the flight instructor was asking me to do. A few months into it I bought a set of David Clarks and a portable intercom. My instructor already had a set of DC. It made all of the difference in the world. I bought a 1981 C-172 to finish my training and it had a built-in Sigtronics 2 place intercom.. ..  and DME. It felt like the Space Shuttle. . lol