Why my two years old's s4i headset is dead after plugging in Cathay Pacific airplane's three pins input? Any inexpensive way to fix it?  The cost to repair it will be around US$90! Any inexpensive way to fix it?

Welcome to the forum.

It is hard to say whether Boeing or Airbus (is that right?) has a design which would blow the voice coils.  It seems a bit unlikely but th forum doesn't have a knowledge base for this, to my knowledge.

I wasn't aware that these types could be repaired.  New ones, full price are about $100 and some Internet sources are way less. (Of course you must know this.)  You may have read that there are counterfeits of some Klipsch headphones out there -- so be careful.

I assume you have returned them to use -- and found a problem -- on an iPhone of the like where, prior to the trip, they worked properly.  True?

In any case, I would suggest you double check and triple check all button and volume settings on the S4i control wand and also on your iPhone.  See if they work with another source of music, and see if your iPhone works with other headphones.

Certainly I don't wish to imply that you have not trouble shot the problem entirely -- but sometimes people jump to a conclusion.

Please let us know what you find.  People on the forum love to hear war stories and we are here to help to the extent possible. 

WMcD