I mailed my Macbook Air to Apple on Friday after I accidentally cracked the screen. They billed me for $755 for the Tier 4 flat rate repair cost. I received the computer back today, and the invoice says that they replaced the clamshell and also replaced my logic board due to an "Audio Issue". I had no problems with the Audio on it before mailing it in with either the speakers or the jack. I called them, and they couldn't give me any further details. Fortunately I have a time machine backup from before I mailed it in. Any ideas as to what would have caused the logic board to fail their testing? Damage while in transit to them? ( I feel like that this is not very likely as they make you take so many precautions before mailing it to them in the pre made box with all the padding and what not.