Apple is privately acknowledging an issue with the enclosure on some of its white 13-inch MacBooks, which in some cases have seen the formation of hairline cracks during normal usage patterns.

The Cupertino-based Mac maker is said to have issued a bulletin to its authorized service providers in March that essentially reverses its stance on replacing the bottom casing of notebooks that may be experiencing these symptoms.

It was reported in November that Apple was refusing to cover repairs for the bottom casing of the notebooks despite its willingness on occasion to address identical problems with the top portion of the casings containing the keyboard and palmrests.

The bulletin to providers reportedly identified four key areas of the case prone to hairline cracking, including the front portion of the case below the palmrests and trackpad, the areas around the I/O ports, the back rear corners, and the back rear ventilation area.

Apple added, however, that other portions of the case could be affected by the cracking issue. For all instances, providers were reportedly asked to inspect the MacBook carefully to determine whether the cracks could be the result of the notebook haven been dropped or other accidental damage caused by the owner.

In the event that providers are unable to identify signs that the user is at fault for the cracks, they're advise to escalate the notebook for coverage by Apple, regardless of whether its 1-year limited warranty has expired.



A collage of cracked white 13-inch MacBook enclosures.

The exception also applies to the black plastic 13-inch MacBook that was discontinued last year, but does not extend to any other member of the MacBook family, according to those familiar with the matter.