Don't rely on it being preserved. Many repairs require Apple to replace or reformat the hard disk, which will result in the loss of your data. Please make sure you back up your data on a regular basis to minimize your data loss. Apple and its AASPs are not responsible for any damage to or loss of any applications, data, or other information stored on your MacBook Air while performing service.
On July 20, 2011, Apple released updates to the 11.6" and 13.3" models of the MacBook Air, which also became Apple's entry-level laptops due to lowered prices and the discontinuation of the white MacBook around the same time. The mid-2011 MacBook Airs were powered by the new Sandy Bridge 1.6 or 1.7 GHz dual-core Intel Core i5, or 1.8 GHz dual-core Intel Core i7 processors, that came with an Intel HD Graphics 3000 processor, and with a backlit keyboard, two USB 2.0 ports, FaceTime camera, a standard of 2 GB of RAM (configurable up to 4 GB), Thunderbolt which shares function with Mini DisplayPort and Bluetooth was upgraded to v4.0. Maximum SSD flash memory storage options were increased up to 256 GB. Both 11" and 13" models had an analog audio output/headphone minijack (that also supports an iPhone/iPod touch headset with microphone), but only the 13" model had an integrated SDXC-capable SD Card slot. These models use a less expensive "Eagle Ridge" Thunderbolt controller that provides two Thunderbolt channels (2 × 10 Gbit/s bidirectional), compared to the MacBook Pro which uses a "Light Ridge" controller that provides four Thunderbolt channels (4 × 10 Gbit/s bidirectional). A USB ethernet adapter was immediately available upon release and a Thunderbolt-to-Firewire 800 adapter became available in mid-year 2012.
Then there is the other part of the MBP with the packages that are sent to your computer without your knowledge that they contain emedded URLs. A collection of the URLs revealed to me the real Apple Cloud is a small group of servers in the Netherlands, not owned by Apple, that get your Cloud data. So if you don't mind your personal data in the cloud going to the Netherlands that should be OK, but of course, Apple won't admit that either.
Some counterfeit and third party power adapters and batteries may not be designed properly and could result in safety issues. To ensure you receive a genuine Apple battery during a battery replacement, we recommend visiting an Apple Store or Apple Authorized Service Provider. If you need a replacement adapter to charge your Apple device, we recommend getting an Apple power adapter.