bolt anchors for concrete hangar floor

NoHeat

NoHeat

En-Route
Joined
Jul 27, 2009
Messages
4,991
Location
Iowa City, IA
Display Name
Display name:
17
I want to install a winch on the hangar floor, to pull the plane in. To hold the winch down I'll use 1/2" bolts, which must be anchored in the smooth concrete floor.

When I vacate the hangar I'll want to remove the winch and bolts, so that nothing's left except holes in the floor --with nothing protruding. Does anybody know the right kind of anchor for that?
 
Here are a lot of options:

http://www.confast.com/

Some solutions will have an expanding bolt that protrudes from the floor. You place whatever on it, then tighten a nut from above. Those kind will usually need to be cut off at floor level when you are finished with them.

Others will have an expanding sleeve that a bolt will tighten down into. Those kind usually have to be left in the hole, but do remain flush. I don't know how easy it is to get them out when you want to remove them.
 
A third option is an epoxy grout anchor. You embed a threaded rod section and epoxy it in place, and use a nut on top of it. It's overkill for strength but it has some advantages with uneven heights/long bolts, and it requires a smaller hole, just slightly larger than the 1/2 rod itself. You would have to cut the rods off after you leave but it's no big deal with end bolt cutters.
 
I'm sort of partial to the idea of the sleeve anchors. When you leave, the anchors stay behind for the next guy. Using other anchors that need to be cut off will require they be drilled out or relocated if the next guy has the same idea you do.
 
1/2" bolts sounds pretty big. What kind of plane do you have? I'd think 1/4" or 5/16" would be plenty. 3/8" at the most. You'll be on a horizontal pull without much resistance.
Which hangars are you in? If in the south T's, are you sure you can't put a chain or cable around the metal framing in the back of the hangar? Or make a bridle that will go from the back two posts?
If you want to set an anchor, the multi-set by Red Head can be inserted to or even below floor level.
http://www.itwredhead.com/product.php?Multi-Set-II-Drop-In-Anchors-12
You can probably get them at Fastenal or order them from Grainger. I've bought them locally but don't remember where.
 
NoHeat said:
I want to install a winch on the hangar floor, to pull the plane in. To hold the winch down I'll use 1/2" bolts, which must be anchored in the smooth concrete floor.

When I vacate the hangar I'll want to remove the winch and bolts, so that nothing's left except holes in the floor --with nothing protruding. Does anybody know the right kind of anchor for that?
Click to expand...

When you install anchor bolts, you should drill the holes all the way through the slab. When it is time to get rid of the anchors, you simply remove the nut and drive the entire assembly down flush with the slab or all the way through the slab if you like.
 
kyleb said:
When you install anchor bolts, you should drill the holes all the way through the slab. When it is time to get rid of the anchors, you simply remove the nut and drive the entire assembly down flush with the slab or all the way through the slab if you like.
Click to expand...
I realize that concrete is porous and so moisture's going to reach the anchors anyway, but wouldn't a through-hole just expose the anchors to that much more moisture and hasten the corrosion process?

For the OP, I asked my hangar owner if he cared if I installed a winch. He said he considered it an improvement and thanked me for it (but didn't cut me any break on the rent!). Point is, I have no plans to remove mine when I leave. Next guy can use it or yank it as he sees fit. You sure you need to plan on removal?
 
I have an expanding sleeve sunk into my hangar floor below the surface. When I'm not using it I cover it with a piece of duct tape to keep dirt and garbage out.

I simply screw an eye bolt in when I need it. My primary use it to pull the tail down on tricycle aircraft to work on the nose gear. It is strong enough that the setup could be used to pull an airplane in if needed.

Paul
N1431A
N2426E
2AZ1
 
kyleb said:
When you install anchor bolts, you should drill the holes all the way through the slab. When it is time to get rid of the anchors, you simply remove the nut and drive the entire assembly down flush with the slab or all the way through the slab if you like.
Click to expand...

Thanks, all, for the suggestions. It took a while because I moved airports, but I ended up installing bolts following Kyle's suggestion.

My previous airport (Cedar Rapids) has high standards for maintenance, and they required that I petition to modify the hangar in any way. I did, and they said I could drill the holes after they had the utilities marked, so long as I either remove the bolts or drive them in flush when I vacate, to avoid tripping hazards.

For unrelated reasons, I then moved to another airport before I drilled anything. At my new airport they weren't so picky. They informally approved my request to drill with no special requirements, but I felt that it would be best to follow the good practices that the previous airport required. So I followed Kyle's suggestion to drill through all six inches of concrete -- that way the bolts can be hammered in flush, years from now, when I vacate.

I used a common kind of bolt like this:

thunderstud-anchor.jpg


It is about 6" long, and I drove it into the hole in the concrete so that it protrudes out of the floor by about 3", which is plenty for the 2 by 4 boards that the winch is mounted on.

Jim asked why such a big bolt as 1/2" and proposed that a much smaller bolt would be okay. I agree -- that's because pulling a plane up a one-degree incline requires less than 100 pounds of force, which isn't going to shear a smaller bolt. However, I was given a winch for free -- and it already had a bracket for 1/2 inch bolts. It isn't that hard to drill a 1/2" hole through 6" of concrete, anyway -- it takes just a couple of minutes while leaning gently on the hammer drill.
 
Last edited:
Jim_R said:
I realize that concrete is porous and so moisture's going to reach the anchors anyway, but wouldn't a through-hole just expose the anchors to that much more moisture and hasten the corrosion processl?
Click to expand...
Actually, Jim, in many cases, since the anchor wouldn't extend to the bottom of the hole, it would have the opposite affect as water entering from the top would be allowed to drain out. Or one could set the anchor or winch base plate in caulking to seal it.

Also, in areas that aren't blessed with sandy soils that drain well, a properly poured slabs is (or at least should should be) placed over an adequate drainage course, typically 4" of crushed stone, to keep moisture from building up underneath.

But either way...holes drilled partially through...or all the way through...

...if there is a corrosion issue, we'll all be dead and gone before it's severe enough to cause a 1/2" expansion or sleeve anchor to fail.
 
Regardless what bolt you use, get a good quality bit of the dimension required by the bolt and a hammer drill sufficient for the job. If you use a lesser drill you will wallow out the hole too much and the expansion bolts won't be nearly as strong. I speak from experience on that one.
 
You must log in or register to reply here.
Back
Top