Squared the horizontal stab to the fuselage by taking measurements from the aft outboard corners to a rivet on the mid side skins as per instructions.
Aligned the F-810E spacers and shim and clamped the front end of the horizontal stab to the aft deck.
Marked out and center punched the bolt hole locations in the splice angle as per detail A Dwg 78 using the outboard edge of the longeron as a reference.
After checking and re-checking all the above we drilled the 4 bolt holes to #30 with an angle drill.
After drilling we noticed that the LH outboard hole had somehow drifted inboard from the center line causing an edge distance problem on the longeron. Fortunately the hole still had to be drilled out to #12 so the situation called for a drill guide to "pull" the hole back to center while drilling to final size. We spent the rest of this session making a drill guide from 1/2" square bar with two #12 holes at the correct pitch. The guide was bolted in position using the inboard hole and we drilled the outboard hole through the drill guide to final size using a long #12 drill from above. The drill guide worked like a charm and the outboard #12 hole ended up perfectly centered.
Drilled and reamed the four bolt holes that attach the horizontal stab to the stab attach bars to final size and installed the bolts.
