As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DOUBLER UNDER RIGHT UPPER WING ROOT SKIN CRACKING (BOTH FORWARD AND AFT SECTIONS). DUE TO NORMAL STRESS FROM GETTING IN AND OUT OF AIRCRAFT, THE UPPER SKIN FLEXES ENOUGH TO CONCENTRATE STRESSES AROUND THE STIFFENERS BEND RADIUS TO CAUSE CRACKING. THIS LEADS TO UPPER WING SKIN FLEXING AND CRACKING AND POPPED RIVET HEADS.