Removed nutplate that had been previously fitted to the firewall. Used firewall through-hole to fit pump backing plate. Sprayed a small amount of machininsts bluing to transfer pump hole locations. Drilled 1/8" holes then updrilled with a step drill to 9/16". Removed some insulating cloth from firewall and secured with hear-resistant foil tape. Covered holes in firewall from nutplate mounting with heat-resistant foil tape. Lightened the backing plate by removed a circular section with fly cutter. Deburred and bolted up pump. Updrilled a couple firewall through-holes to allow for misalignment. Located holes for three 1/8" rivets to hold backing plate to firewall. Deburred holes, cleaned bluing with acetone, and mounted pump with three AN-4-12 bolts with washers.
