As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAINTENANCE FOUND A VISIBLE CRACK ON THE LOWER SKIN OF THE CENTERWING BOX. THE CRACK IS LOCATED ON THE FORWARD EDGE OF THE AFT WING SKIN, AND AFT EDGE OF THE FORWARD WING SKIN. THE CRACK ALSO PROPAGATED THROUGH THE UNDERLYING STRINGER IN THE CENTER WING BOX. MAINTENANCE COMPLIED WITH ER/A 535437-14AD, REV ORIGINAL.