Fuel tank trap door - 2.5 hours

I managed to pick-up the proper hinge (MS20257-3) so I moved back onto the fuel tanks. Figuring out how to best set up the trap door took an amount of head scratching.  The trick is that you can't really follow the plans for the upper hinge as the depressed ring pattern on the rib prevents placing a rivet where needed. Looking at other build sites, one method employed is to leave the top hinge longer to bridge the gap. The next challenge is to layout the hinge so that there is good support of the hinge loops. In my opinion it is much better to have 2 loops per side.

Lots of sketching, checking, moving, re checking. It's not so straight forward.

This is the final version of the layout I chose

I then drilled to #40 and then countersunk the trap plate for a NAS oops rivet. My opinion is that the NAS rivet should be alright here as this is not a part that is subjected to stresses. However, since I only have two rivets to hold the top hinge I have decided to countersink the thicker hinge material for an AN426AD3 rivet.

Most important I thought in the process was to install a spacer under the top hinge the same thickness of the trap plate so that is sits flat against the rib.


Mental note.....MEK does not take off sharpie marker on hinge material!!! Nothing seems to.
I even tried buffing and sanding it off...GRRRR!