This is my first real post so here it gos. Well I recently bought a 108-3 and would like to redo the floors in her. Now shopping around for materials I'm finding plywood for it through an aircraft supplier is about 200 bucks a sheet for "aircraft" grade mahogany plywood. Now I don't mind paying the price I knew owning an aircraft could be and is an expensive hobby but I checked at the local specilty lumber yard and a sheet there is 21 bucks a sheet. So i guess I have 2 questions one what makes the aircraft sheet an aircraft sheet? And the other is has anyone ever been denied say an annual for using something other in a situation like that?

Thanks
Jack

The Rev. wrote:This is my first real post so here it gos. Well I recently bought a 108-3 and would like to redo the floors in her. Now shopping around for materials I'm finding plywood for it through an aircraft supplier is about 200 bucks a sheet for "aircraft" grade mahogany plywood. Now I don't mind paying the price I knew owning an aircraft could be and is an expensive hobby but I checked at the local specilty lumber yard and a sheet there is 21 bucks a sheet. So i guess I have 2 questions one what makes the aircraft sheet an aircraft sheet? And the other is has anyone ever been denied say an annual for using something other in a situation like that?

Thanks
Jack

I had a 108-2 and I was looking to do the same. The aircraft mahogany plywood has the mahogany veneer on the core, forgot what it was. It's MUCH, MUCH lighter than the plywood from anywhere local I could find. I ended up being able to lightly sand my floorboards and stain them fresh again and they came out nice. Even the new aircraft wood stuff was a little heavier than the original floorboards I had.

Since it is not a structural component, chances are that you will not get into TOO much trouble using non-structural wood. However, it also WILL not be as strong, and perhaps you will crack it when putting too much weight on it.

You have a few options IMHO:

1) Sand down the existing floorboards and epoxy laminate a veneer of 1/32" or 1/64" birch aircraft plywood, available from your local model airplane hobby shop, or mailorder through Balsa USA. IMHO use West Systems (see below) to do this lamination and then to finish the wood.

2) Buy aircraft quality but un-certified birch plywood in small sheets through Balsa USA, or Midwest (model airplane companies). This will be far less expensive than airplane certified wood, but just about the same quality.

3) Sand down your existing floorboards and apply a layer of medium fiberglass cloth on each side to strengthen and protect. Your local EAA chapter will probably have some composite airplane builder who can help with the fiberglassing. Also, you can get the very helpful West Systems publications and pamphlets that describe how to use their products for various tasks. West Systems (Gougeon Bros.) is a wooden boat materials company but their products are VERY good and IMHO very appropriate for this use.

I've done floors with Russian Baltic Birch, It's clear, has relatively fine lamination, water resistant and relatively cheap, usually come in an odd ball 5'x5' dimension from 1/4" thick and up. Should be available at lumber stores that specialize in plywood.
Add a few coats of urethane hard floor finish and it should be good for another 40 years.

It's probably a lot like Concrete Form Plywood. The form Ply has seven layers compared to five. Strength is not even comparable. It also uses a different glue so it can be exposed to water for years without coming apart. If it isn't structural you might consider Marine Plywood. It will take the weather but I doubt is much stronger than regular plywood.

72 and earlier Chevy Suburbans had plywood floors in the back and that is usually the best part of the bodies. I think you won't regret buying the right stuff.

Flap, are we absolutely sure the floor is not a structural element? The reason I ask is that N28751 has an aluminum diamond plate floor. If it's ok, I'll just glue some rubber mat or carpet down on it. I hate the look.

Emory Bored wrote:..... N28751 has an aluminum diamond plate floor. If it's ok, I'll just glue some rubber mat or carpet down on it. I hate the look.

Not to be a nitpicker or naysayer (well, maybe just a little), but is there any paperwork on that diamondplate? Structural or not, that sounds like it'd be OK for a 4x4 monster truck but not a Luscombe. It can't be too much of a big deal to rip that out & put in the right stuff (again, plywood).
I'd also suggest checking with marine places to see what they have. Of course, a "marine" tag might not add much less of a premium than an "aviation" tag does.

hotrod150 wrote:

Emory Bored wrote:..... N28751 has an aluminum diamond plate floor. If it's ok, I'll just glue some rubber mat or carpet down on it. I hate the look.

Not to be a nitpicker or naysayer (well, maybe just a little),

Well if you're not going to be a nit picker then who will? No paperwork other than a signed off annual in May. It comes out before next annual for sure.

EB,

I was told the floor in the lusc was non-structural. It is real easy to make a replacement out of wood.

Use home flooring underlayment plywood. Clear wood,no plugs and water resistant and very strong. Comes in 4x8 or 4x4 and a lot less expensive than Baltic Birch.

Jim

hotrod150 wrote:

Emory Bored wrote:..... N28751 has an aluminum diamond plate floor. If it's ok, I'll just glue some rubber mat or carpet down on it. I hate the look.

Not to be a nitpicker or naysayer (well, maybe just a little), but is there any paperwork on that diamondplate? Structural or not, that sounds like it'd be OK for a 4x4 monster truck but not a Luscombe. It can't be too much of a big deal to rip that out & put in the right stuff (again, plywood).......

Oops, shot off my mouth before thinking (again). The Stinson subject of this post made me forget I was talking about a Luscombe: "No wood, no nails, no glue". I doubt the original factory floor was plywood, probably aluminum. But I'm sure not diamond plate.