As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE ATTEMPTING TO CLIMB ONTO THE CABIN ACCESS STEP, IT TORE OUT OF THE FUSELAGE. EXAMINATION REVEALED THAT THE STEEL SUPPORT DOUBLER INSIDE THE FUSELAGE LOWER CORNER HAD CORRODED IN CONTACT WITH THE ALUMINUM SKIN, WATER CAN ENTER AT THIS POINT AROUND THE STEP ATTACH BOLTS. THERE WAS VERY LITTLE LEFT OF THE DOUBLER. THE DAMAGE TO THE ALUMINUM STRUCTURE WAS LIMITED TO THE SKIN DIRECTLY IN CONTACT WITH THE DOUBLER.