What was found
F/A REPORTED A LOUD BANGING NOISE BELOW THE ACFT WHILE SEATED ON THE AFT JUMPSEAT. IT WAS DISCOVERED THAT THE CATWALK HAD REMAINED STUCK IN THE UP POSITION -BLOCKING THE EMERGENCY ESCAPE PATH. MX FOUND THE REMOVABLE CEILING PANEL OUT OF ADJUSTMENT AND RESTRICTING THE CATWALK FROM RETURNING TO THE "EXIT PATH" POSITION. THE CEILING PANEL WAS ADJUSTED AND A FUNCTIONAL CHECK PROVED THE CATWALK MOVED FREELY.