Leaked document shows how Apple decides to replace or repair your iPhone

It can be hard to predict what's going to happen when you visit an Apple Store to get your iPhone repaired.

Apple's warranty for most products covers eligible repairs for its products, including the iPhone, for a year after purchase.

But what's an eligible repair? Damages specifically not covered includes anything stemming from "accident, disassembly, unauthorized service and unauthorized modifications."

A 22-page document recently leaked on Dropbox shows how Apple instructs its technicians and authorized service partners to inspect iPhones for repair and how to determine if they are eligible for an in-warranty repair (inexpensive), an out-of-warranty repair (more expensive), or if it's a problem that Apple can't fix (you need a new phone.)

The document seen by Business Insider is called the Visual/Mechanical Inspection Guide, is dated March 3, 2017, and covers iPhone 6, 6S, and 7, as well as the associated Plus models. Apple technicians called Geniuses call it a "VMI."

"We have one just like that for all of the products," one Apple retail technician told Business Insider. "Used more for the physical inspection and how to determine cost for damage. That's basically half the training for iPhone techs."

VMIs are "something we use but, we don't refer to it all that often, unless we get some oddball issue," another Apple technician told Business Insider. "We can normally pick out abnormal issues without using it."

So what does the VMI look like? Here's one chart that provides an overview with photos about what common issues are covered:

Most of these issues should not be a surprise if you've been a long-time Apple user. If there's been water damage to your iPhone, you'll have to pay.

The guide includes which questions to ask if a technician thinks a phone has been water damaged, which reveals that a technician must take apart the phone before denying warranty coverage.

However, it is worth noting that a single hairline crack is covered under warranty, in what appears to be a change since 2014. (Older versions of the guide are available online.) And if you're seeing dead pixels on your screen, you have to specifically ask for them to be fixed.

Other parts of the guide focus on identifying an iPhone's internals and whether any parts have been swapped. Any device with a non-Apple battery or missing parts is ineligible for service.

Another thing Apple won't fix is cosmetic damage:

If you have a problem that's not covered in this guide, that doesn't necessarily mean that you won't get a repair under warranty.

Business Insider was told by an Apple retail employee that the VMI isn't the last word on whether a repair is covered - at least unofficially. "There are always those one-off issues that the phone is technically not covered under warranty but we swap the phone anyways under warranty," an Apple technician said.

Apple didn't immediately return a request for comment.