TM  5-5420-209-12 Table  4-3.  Unit  Preventive  Maintenance  Checks  and  Services  (PMCS)  for  the  interior  Bay  cont. Location Interval Item To Be Inspected Equipment Is Not Item to Service/Check Ready/Available If 21 Weekly Tie Down Pin Inspect pin weld seams for broken welds. Broken  welds  noted  or Inspect pin for erosion of pin surface. erosion  of  surface  area prevents  securing  bay  to transponder. 22 Weekly Skin Surface Inspect surface area for punctures, holes and Any damage which allow dents  exposing  interior  ribs. water into bay interior (If in doubt, perform soap bubble  test). Inspect  seams  for  cracked/broken  welds. Cracked/broken   welds noted. 23 Weekly Tie Down Pin Inspect pin weld seams for broken welds. Broken  welds  noted  or Inspect pin for erosion of pin surface. erosion  of  surface  area prevents securing bay to transporter. 24 Weekly Bridge  Latch Inspect brackets, shims and strike catches for Broken welds, binding or Receptacle cracks, broken welds, binding and deformation  prevents deformation. engaging  latch  noted. 25 Weekly Unfolding Ensure unfolding mechanism functions Broken welds noted or Mechanism properly. deformation  prevents Inspect cover plate, spring pins, pins, lever, mechanism  for and connecting link for cracks, broken welds functioning  properly. and  deformation. 26 Weekly Skin Surface Inspect surface area for punctures, holes and Any damage which allow dents  exposing  interior  ribs. water into bay interior (If in doubt, perform soap bubble test). Inspect  seams  for  cracked/broken  welds. Cracked/broken   welds noted. 27 Weekly Foldlock  Latch Inspect brackets, supports and pins for cracks, Cracks,  broken  welds broken welds and deformation. noted or deformation causes  binding. Inspect  springs  for  deformation  and  stretching. Springs  stretched. 28 Weekly Skin Surface Inspect surface area for punctures, holes and Any damage which allow dents  exposing  interior  ribs. water into bay interior (If in doubt, perform soap bubble test). Inspect  seams  for  cracked/broken  welds. Cracked/broken   welds noted. 4-21 Item No. P r o c e d u re