Elevator Trim Upper LH Skin MC0334200-4

The outboard tip of the elevator trim skins for the Cessna 170, 190 and 195 has always been an area prone to cracking. This is because the original skins had a formed corrugation at the tip that had to be "unformed" or flattened either at the factory or in the field before it could be securely riveted in place.

The process of forming that corrugation and then flattening it again work hardens the material, making it brittle and prone to cracking around the rivet. The precision hydraulic forming process allows the manufacturer to skip the final corrugation in the skin, leaving the problem tip unformed and ready to rivet. This is in contrast to Cessna's rotary forming process, which does not allow the option to skip a corrugation.