A report on Thursday offers a rare look inside Apple's secretive EFFA quality control division that runs down and fixes launch day hardware issues before they become larger, more costly problems.

Citing unnamed employees previously part of Apple's early field failure analysis group (EFFA), Bloomberg Businessweek put together a profile on the team of engineers tasked with pinpointing hardware defects just hours after a device launches.

For example, when a new iPhone hits store shelves, EFFA brings in engineers who designed the latest handset to field reports of faulty units just hours after a product is released to the public. According to the publication, engineers in Cupertino receive special courier packages containing defective hardware returned to brick-and-mortar Apple Stores from around the world.

Dissecting faulty units in-house, engineers are able to quickly determine the problem and hopefully issue a fix that will applied to Apple's global supply chain. Spotting a problem in the very early stages of a product's release can save millions of dollars in costly fixes and supply chain tweaks.

Sources point to EFFA's handling of the original iPhone in 2007. When the smartphone launched, returns came back with what appeared to be defective touchscreens. Engineers tracked the issue back to a flaw in manufacturing that allowed sweat from a user's face to enter the screen near the ear speaker, causing the display to short. The problem was solved by adding a coating to seal off the area, a technique Apple quickly pushed out to partner suppliers to avoid further complications.

In another iPhone-related case, EFFA engineers discovered the design of the handset's speaker restricted airflow and built up pressure during air transport from China, causing the component to fail upon arrival. The fix was to create holes in the speaker housing, a simple solution that saved Apple from constantly replacing entire speaker assemblies.