Confused about seat floor stiffeners

OK, I'm beginning to reach the point where I believe the construction manual is flat-out wrong here, unless I'm missing something very obvious. I'm hoping someone can shed some light here.

Today I did all the prep work on the aft seat floors - match-drilling the stiffeners, drilling the rear seat hinge, deburring and dimpling everything, etc. Next up will be back riveting the stiffeners to the floors.

But here's what confuses me. The manual says:

Back rivet the F-830B-1, D-1, E-1, & F-1 Floor Stiffeners to the F-830-1 Left Seat Floor using the 3/32 flush riv- ets called out in ?Seat Floors?, DWG 77. (Only rivet the three F-830B-1 Floor Stiffeners that use 3/32 rivets, and only one of the rivets used to attach the F-830F-1 Floor Stiffener is 3/32.) NOTE: Do not rivet the F-830C-1 Floor Stiffeners at this time.

Click to expand...

The particular bit in question is that last bolded part, about not riveting the F-830-C stiffeners yet. Normally, with a directive like this, I'd expect to see that something else has to be riveted in assembly, or the part in question would end up blocking access later on. But I see no indication of that. The directive to rivet these stiffeners comes later on, when the floors are being installed permanently, and there are no indications of any sort of interference.

What's more, the steps for permanently installing the floors don't even make sense to me. Those steps have me cleco both of the seat floors in place, along with the aft baggage floor, and then blind rivet all those pieces to the understructure. Only then does it say to rivet these six stiffeners in place - but now I'll have to flush-rivet them and reach under the seat floor to buck them.

I just do not see any reason for this complication. Can some of you -8 builders maybe tell me what I'm missing here? It seems like there's no reason not to just go ahead and back rivet all the stiffeners at once.

probably because you have to flex them to get them under the side skin bulkheads. I riveted mine and you can install them with a bit of "English", such as flexing the front seatbelt anchors in a bit, etc. I figured that I may have to remove them in service, so I should be able to install them as a single piece.

Ahhh yes, that would make sense. Funny how that didn't occur to me, even though I was just removing them this past weekend and had to do the bendy dance. I agree with your reasoning, that they may have to come out one day...and if you got yours in, then I'm probably going to rivet them beforehand like you did.

Thanks!

I riveted them in after pop riveting the rest of the floors. Hope not to need to take them up, I do have some conduit in place should I need a wire or two. That said, I expect I could get them up if needed, worst case drill out a couple of the stiffener rivets.

Riveting them is very similar to the bottom wing skins.