Original MacBook Air HD would no longer mount
1 - 2 horas
My original 80GB HD was showing signs of erratic failures until one day it decided to leave me on my own and wouldn't mount anymore (using Disk Utility).
The rest of the machine was working fine and my laptop was still shiny, which encouraged me to change the original HD and take this opportunity to increase the volume space to 120 GB as indicated on the iFixit website. Browsing through the manual and video it didn't look that hard a repair to do it myself, and I decided to place my order.
The repair went nice and easy. The only issue I faced was to remove the foam from the original HD and paste it back to the new HD (well, what I managed to recover from the original one!). The new HD formatting and OS X installation went seemlessly and within an hour I was able to enjoy using my MacBook Air again.
Remember to backup your files regularly. My latest backup was a bit outdated and I lost a few files (recent pictures). Lessons learned for the future!