Thursday, August 27, 2015

Section 35 Begin

Started Section 35 - Access Covers and Floor Panels today. The first thing they have you do is prep and rivet the rear floor pans into place. I got all the holes drilled, deburred, dimpled, scuffed, and primed in fairly short order. Riveted a few nutplates to the bottom side and thought things are going quite nicely so far, all that's left now is to drop them into place and rivet them down! I must say, this part of the plans caught me by surprise how difficult it was. In my mind, I thought "it's a bunch of blind rivets, should take 10 minutes" but in reality there are a number of solid rivets all around the perimeter, you have to match-drill into the center section spar, and worst of all the panel itself is *extremely* difficult to wedge into position.

The floor panel has three cutouts along the forward side that are supposed to go around the seat brackets and the middle reinforcing hat channel attached to the spar. Well, on mine (and others I've read about) the cutouts were just a tad too narrow to fit around the seat brackets, and this makes installing the floor impossible. It's not evident right away that this is the problem unless you're specifically looking for that, and that's what makes it tricky. Instead, you'll just want to push harder and harder until SNAP something gives. Usually it's the flange on the side of the panel that will buckle. If you're lucky (like I was) it didn't crack, it just bent a bit and I could straighten it back out.

Well, after salvaging my screwup on the L floor panel and getting it all riveted into place, I thought I'd be a hero and take a million photos of the method I thought I had "perfected" now for the R floor panel to show others "the way"... here's what I came up with:

Fiberfrax insulation laid out, and two scrap sheets of thin aluminum to help the panel slide past the seat belt brackets and rivet heads

Panel laid into place with the aluminum sheets on the side helping it slide down



Check for appropriate clearance around the seat brackets

Take an automotive panel/upholstery pry tool to help wedge the panel from the backside

Now just pry it forward to clear the rear spar center section, give her a little push, and....


OWWWWEEE.

Oh for crying out loud! It was going so perfectly too. Just a bit too much pressure in the wrong spot and the damn thing buckled again... this time causing my hand to slip and go right into the sharp, unfinished corner of the aluminum sheet I had so proudly put in place to guide the panel down. So much for a flawless install procedure.

The buckle in the floor panel. Again like the L side, it didn't tear or crack thankfully and could be straightened out by careful and judicious use of the flush rivet set on the 3x gun.

So, in all reality it wasn't the worst situation in the world to be in. Got my hand all patched up (yes that's electrical tape holding the band-aid in place), stuck in a bunch of clecos and straightened out the buckle. In a few hours' time I had both panels fully riveted into place, and a very sore back from sitting in a number of incredibly awkward positions:

L floor pan after riveting


R floor pan after riveting - buckle is erased thankfully!

Whew! Glad that bit is over. Note to future builders: good luck! These floor panels stink. But, when they're done, you have a nearly complete floor in your entire airplane.. yay!

Tomorrow if there's time we'll probably rivet down the rest of the back seat panels (they were left up to provide access to riveting the aft edge of these floor pans) and continue with Section 35!