5. Using a 1/2 inch diameter drill bit and a drill stop gauge set, drill a 1/2 inch (12.7 mm) hole, 1/2 inch (12.7
mm) deep into the fuel tank armor plate (1) at location (2) drilled in step b.3. above. Tap hole (2) using a
bottom end tap set to 9/16-12 UNC-2-A. Install steel insert (MS51831-204) into threaded hole (2).
Figure 2-3. Drilling, Tapping and Installing
Steel Insert in Fourth