Removable floors

This is information for 7 builders contemplating removable floors. 180 nutplates!
First a call was placed to Vans to ask if there were any issues. The answer was no data showing issues. Builders decision but it's a great deal of work for small reward.
I personally know a few builders who had to drill out their floors. I like the idea so removable floors will be done. This may not be the right way but it's how I'm doing it.

I chose to prep the ribs while the center fuse was being built. Everything has to come apart to be prepped so adding nut plates to the ribs will be one more step before riveting the center fuse.
Forward and seat floors will be standard nutplates up to and including the bulkhead behind the seat. The baggage floor will be flush.
With the center fuse clekoed and ready to be disassembled, I made notes on the floors showing which nut plate would be under each hole then counted them. Totals are below.

Remove the floors. You want the holes left #31 so they can be clekoed back on for assembly of the fuse. 1/8" clekos hold well in a #8 nut plate and will fit the existing holes in the floors. You can drill them later.
Next step is drilling all the rib nutplate holes #19 for #8 screws. Use your method to drill all the nutplate rivet holes. I used two nutplates (2 lug and 1 lug) with a screw inserted from the wrong direction as templates for drilling rivet holes.
Next the tedious work. Vans suggests the nutplate threads be chased with a tap to make screws easier to install and remove. Your choice. I did it but after, they need a slight squeeze with a plier to give the screw a little clamping force. You don't want screws falling out. Finally, prep them as usual for install. I actually prime all nutplates. OCD!

It's a lot of work. It's also added cost and weight. Choose wisely. Here's the nut plate count, give or take one or two. This includes the nutplates you would be installing on the forward floors. They are removable per plan. You can do the math.
K1000-08=80, forward and seat floors
MS21051-L08=46, forward and seat floors
K1100-08=46, baggage floors
MS21053-L08=8 baggage floors

wirejock said:

....
Next the tedious work. Vans suggests the nutplate threads be chased with a tap to make screws easier to install and remove. Your choice. I did it but after, they need a slight squeeze with a plier to give the screw a little clamping force. You don't want screws falling out. Finally, prep them as usual for install. I actually prime all nutplates. OCD!
......

Click to expand...

You should not need to tap nutplates... just use some BoeLube for the first screw you install and they will wear in nicely for future use.

This is the finish on the K-1000 nutplates -

• K1000-(*) Cadmium plate per AMS-QQ-P-416, Type II, Class 2, plus Kaylube molybdenum disulfide dry film lubricant per AS5272.

They are cadmium plated like your nuts and bolts - they actually have 50% thicker plating, they don't need priming...

For that many nutplates it's probably worth springing for a real nutplate jig - it will do a better job quicker.

http://www.browntool.com/Default.aspx?tabid=344&CategoryID=347&Level=a&ProductID=2085

Nutplates

Thanks Gil.
If nutplates were consistent, I would not chase threads. On typical install, I run a screw in with Boelube. Many are so tight the screw threads get messed up. Some have no clamping force at all and have to be squeezed. I chased these so every one would be similar clamping force. It's an optional step in my write up.
A jig would be a good purchase.

az_gila said:

You should not need to tap nutplates... just use some BoeLube for the first screw you install and they will wear in nicely for future use.

This is the finish on the K-1000 nutplates -

? K1000-(*) Cadmium plate per AMS-QQ-P-416, Type II, Class 2, plus Kaylube molybdenum disulfide dry film lubricant per AS5272.

They are cadmium plated like your nuts and bolts - they actually have 50% thicker plating, they don't need priming...

For that many nutplates it's probably worth springing for a real nutplate jig - it will do a better job quicker.

http://www.browntool.com/Default.aspx?tabid=344&CategoryID=347&Level=a&ProductID=2085

Click to expand...

I made a nut plate jig, but it was not perfect. It was very helpful, I just have to allow for the slight misalignment. If there were 20 more to do I would get the tool. Also, use the NAS rivets for them and it will save huge time with countersinking too. I think with the right tools and technique, it will be done in no time. Get some extra floating center nut plates for those pesky holes that just don't match. I had a couple.

In favor of nut plates - in the build process, in order to finish this step with fully fitted, then painted parts, one can move forward with the build and leave little back work for later. This allows access later in the build for wiring etc and avoiding having to think too far ahead for options. Allows near term focus.

For my tanks, I borrowed the tool. It saved a bit of time but wasn't a huge improvement. I ended up clamping the tool in place, one hole at a time, and while that was faster than installing a crew and removing it, it wasn't much faster.

The bigger advantage was that it was easier to control the nutplate orientation with the tool, and this made it worth having.

Dave

No tool

Sorry guys. All 180 done with no tool. Yes, all perfectly aligned. I checked as I went.
Place the home made nut plate screw jig in the hole. Center punch one hole. Drill the hole. Insert cleko. Center punch the other hole. Drill. Lather, rinse, repeat 180 times.
The most important tool was a center punch. I used it before drilling through the nut plate rivet hole to make sure the drill wouldn't wander. Time will tell. I can always drill the few that done line up perfect and use floating nut plates. The rivet holes will still line up.

wirejock said:

Sorry guys. All 180 done with no tool. Yes, all perfectly aligned. I checked as I went.
Place the home made nut plate screw jig in the hole. Center punch one hole. Drill the hole. Insert cleko. Center punch the other hole. Drill. Lather, rinse, repeat 180 times.
The most important tool was a center punch. I used it before drilling through the nut plate rivet hole to make sure the drill wouldn't wander. Time will tell. I can always drill the few that done line up perfect and use floating nut plates. The rivet holes will still line up.

Click to expand...

But you DID have a tool, just a custom made one! - Building is always better than waiting. Bravo . . .

Removable Floors

Yes, I decided I had to have removable floors too! It's a lot of work. And I "painted myself into a corner". I riveted all the nutplates on the ribs prior to assembly. Then I found most of the outboard seat rib nutplates had to be removed in order to rivet the fuselage side skins. Then the nutplates had to be riveted back onto the seat ribs. Just another example of the "law of unintended consequences".

In my case, in addition to the improved maintainability, I have an additional bonus in that I don't have to request a pre closing inspection on the fuselage from MDRA. I already paid for one on the wings and empennage before I started on the fuselage.

Corner painting averted

terrye said:

Yes, I decided I had to have removable floors too! It's a lot of work. And I "painted myself into a corner". I riveted all the nutplates on the ribs prior to assembly. Then I found most of the outboard seat rib nutplates had to be removed in order to rivet the fuselage side skins. Then the nutplates had to be riveted back onto the seat ribs. Just another example of the "law of unintended consequences".

In my case, in addition to the improved maintainability, I have an additional bonus in that I don't have to request a pre closing inspection on the fuselage from MDRA. I already paid for one on the wings and empennage before I started on the fuselage.

Click to expand...

Thanks Terry.
I hadn't considered that.
I will leave those in storage till the side skins are on.

Brown Tool Nutplate Jigs are great!!

Hi Larry,

Yeah, I also decided to make my floors and baggage side covers removable. And since that wasn't enough work, I decided to use flush head screws too!! Yes, it was a ton of work and it would have been easier if my knees and back were 20 years younger. I've got a -7 QB and I did this while it was on the rotisserie. The main reason for doing this was I've got some avionics boxes that I plan to put under the floors. I also like the idea that I can inspect under the floors if I want to. I don't know how often I'd do this, but if they were riveted on, the answer would be never...

The reason I'm responding to this is to put in a good word for the nutplate jigs that Brown Tool sells. I've purchased a few other nutplate jigs from some other vendors and I wasn't all that impressed with the quality of the tool. The pins weren't aligned correctly and they didn't have a hardened drill bushings in them so they wore out rather quickly. The jigs from Brown Tool on the other hand are great. They make drilling the rivet holes so easy, even an engineer can do it!!

I decided to go ahead and buy the 12 piece nutplate jig kit from Brown. http://www.browntool.com/Default.aspx?tabid=344&CategoryID=347&Level=a&ProductID=268

The nice thing is they were willing to "mix and match" the kit for the types/sizes of nutplate jigs I needed for no additional cost (except if the replacement was more expensive, then you paid the difference. If it was cheaper, you saved some money!!).

I knew I was going to use a lot of nutplates (especially on the sub panels for the avionics) so the way I looked at it, if it saved one screw up on drilling a nutplate rivet hole, the 12 piece kit paid for itself. YMMV.

I hope this helps.

Jeff

Jig

Thanks Jeff
I post these so noobies have access to the information they need to make informed decisions.
So, yes. All information helps.
I may buy a jig for future use. There's still lots of nutplates to install.

The nut plate jig makes installing them really quick and easy. I'm really, really glad I bought mine. That one tool probably saved me a few hours of work on the seat pan & baggage floors.

Floors

Point of reference! I prematurely pop riveted the floors of my -8 before flap fairings were in place, so they all had to be removed. I (slow worker) and Dennis Millsap (quick worker) spent less than 40 minutes (total) on removal and re-installation with new LP4-3's. Nice to have a good supply of the pop rivets on hand and one or two small punches to drive out the old mandrels before drilling - you might break a punch. It is not a very big job or hard to do....... Signed by guilty party who had fun with the HF pop rivet tool both times.

I went with removal floors because I think the full step on each side (for an A) should be part of the annual condition inspection .

As far as the added weight, my primary means of saving weight in my RV is for me to lose some and keep it off.

LettersFromFlyoverCountry said:

As far as the added weight, my primary means of saving weight in my RV is for me to lose some and keep it off.

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My plan as well. How is the problem.

When I built my -9, I gave some serious consideration to putting the floor down with platenuts. However, I was fanatical about keeping my plane as light as possible (990 lbs for the first flight) and installed them with pull rivets.

In eight years of flying, I have only drilled up the left side once and that was to do upgrade to the SkyView so I could run the pitot and AoA lines under the floor into the tail cone.

That said, after reading what Bob said about getting to the steps, had I built and "A", I would definitely make them removable for two reasons. 1. General inspection and 2. Replacement. After reading about all the cracked steps, you had better plan on removing and reinstalling the steps. I would also give some consideration to having a "patch" welded to them prior to your installation.

The Floors are removable

Save yourself time, money, and weight. Use the pop rivets to install your floors as per plans. You can remove the floors much faster drilling out the soft aluminum pop rivets then removing all those screws. The only thing that takes time removing the pop rivets is removing the rivet heads from the drill bit.

If you twist out the head of one of your screws (and you will) then you will be drilling out a steel screw instead of a soft rivet. I removed my floors once to install autopilot servos and it took just minutes!

Just think about it!

Danny King said:

If you twist out the head of one of your screws (and you will) then you will be drilling out a steel screw instead of a soft rivet.

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Or, use a screw that isn't designed to cam out and strip, like a hex/allen head or torx screw.