The Poly Fiber Instruction manual warns about over tensioning the fabric during the three stage Ironing process as it can deform metal parts. I was deeply concerned that this may occur on the Turtle Deck since it is an open ended frame so a Test Fit was in order to check for proper fit on the Fuselage. Luckily there was no deformity and as I gained expierence I found that it was next to impossible to deform parts, even light weight aluminum parts. The only caveat is, if you glue the fabric too tightly around the part to begin with then it is entirely possible to deform it as the fabric pulls itself together. The best practice is to leave a little slack in the fabric when it is first glued to the frame, then as it shrinks it will not deform the part it is covering.