Blind nuts, or threaded inserts
 

Hello all, I have been wanting to reinforce my landing gear mount. Right now I am putting bolts into threaded wood, as was intended from the factory. Recently, I had a bit of a rough landing, nothing to really worry about, except when I got the plane back on the stand, I noticed one of the bolts was coming out. Come to find out the small amount of stress on landing stripped the threads in that hole.

Now, I want to reinforce the threads and was wondering....should I use blind nuts, or threaded inserts. Which one would would be best in this situation? Keep in mind I'm not sure of the access to the holes from the inside of the plane, bit I'm pretty sure they are accessable. Thanks for any help here.

Either one would work just fine. For blind nuts, you would need to get inside; for inserts, you wouldn't. I usually use blind nuts, but that's just because I've got lots of them on hand.

Blind Nuts would be stronger if you can get to the landing gear plate....Good Luck, Dave

Good advice already.

However, one question. Are the bolts you were using steel? I've worn out a couple of AeroWorks models that came with blind nuts and steel bolts holding on the gear that I converted to threaded wood and nylon bolts when assembling them. Oh wait, that's not true. The first one was actually the reason for the conversion as it started life with steel and steel. When that gear tore out on a ground loop and took most of the bottom with it, I rebuilt it to accommodate the nylon bolts. When I got the 2nd model, it was converted on assembly. And both have proven the bolts are strong enough to last, yet small enough to "save the fuselage". They both have really been flown a lot. AW just recently got the Extra300 back in stock after a year or so, and the replacement is in the shop getting assembled. The other model (Yak 54) got replacement servos a couple of weeks ago. It's gotten pretty ragged since 2009. About the only shiny parts on it were the nylon gear bolts that got changed every couple of years. The wood doesn't strip when the bolts are the right size and nylon.

Thought about converting to nylon bolts, but was told with the size and weight of the plane, that might not be such a good idea. All my other planes have been con vertex to nylon bolts, and I'm convinced has saved me hours of repair time. Thanks for all the info guys. I'm thinking blind nus for sure, I'll have to think about nylon bolts. Not sure if the change will weaken the over all strength of the landing gear.

I use a different number and size nylon bolt depending on the model. My Extra300 for example came with 3 steel 6-32 bolts into steel blind nuts. Fate caught up with it in it's second or third year and that steel and the carbon fiber gear tore the belly out. Now it has 3 nylon 10-24 nylons into the plywood. I did that back in 2010 during it's first year. A week or so ago it hit a hole in the runway at touchdown and stripped the gear off. One hole in the covering and 3 new bolts. The new patch was over the previous patch from 6 years ago.

CA after threading works too.

The Extra is a 7lb model. I've got a couple of heavier ones with 1/4-20s used with 10-24s. Lot's of flexibility by mixing. The heaviest has split mains. A left and a right gear with two bolts each. I put the 1/4-20 inboard and the 10-24 outboard on each. The 1/4-20 deals with the lever effect every touchdown. It there is a twisting stress or impact on a wheel, the 10-24 provides a release if needed.

With metal or CF gear, using steel bolts pretty much guarantees something is going to be destroyed.

I use 1/4X20 nylon bolts tapped into a 1/4 inch plywood plate on my 20 pond 50cc powered plane. That's a 3/16 aluminum landing gear. It has survived many bad landings. Dan.


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In my case, it depends on what I'm holding as to whether I use inserts or nuts. Anything that has a load with any tension gets nuts. Since an insert doesn't really make a bolt/screw install any stronger, other than making the threads themselves more durable, I only use them in non-loaded or 90 degree load situations. Since I build boats as well, the only place I use inserts is in the transoms as drains or in the case of winged boats, in the ends of the wing for the nylon retaining screws.

What I'm doing this to is an old g-shark. It weighs probably 12 lbs with the engine. So, I think I am definitely going nylon bolts, and keep the 1/4-20 size. I have a stick right now that I made the mistake of going too small on the bolts. I was snapping them like every third landing. You guys are the best! All great advise, and really helped me make a good decision. I hope this place never changes, as well as who comes here.