Much of steel tubing that made up the bottom truss of the fuselage needed to be replaced.
I built a solid table and blocked each tube and the tail post. Then removed the fuselage and built a new bottom truss in the jig created.
I placed the fuselage back on the table and removed the rusted out bottom. Afterward I tack welded it all back together and added other tubes per the gross weight increase STC.
Eventually the door frame, and much of the frame above the cabin was also cut out and replaced as well.