I'm assembling my first plane, a HobbiStar 60, and when mounting the engine mount I failed to put the lock washer ( I put only the flat ones). Anyway, I pulled the screws out and whenscrewing them in again with the 2 washers, I stripped the holes of blinf nuts in firewall. What would be the best fixing for this. I dont wanna cut the firewall down or something drastic. How about bigger screws ?
Any ideas ?
Thanks
Juan</p>

I would recommend pulling the fuel tank out and replacing the blind nut or nuts as necessary. Once the fuel tank is out you should be able to see the nuts on the back of the firewall and pushing them out isn't really that hard. Then put a drop of epoxy on the new nut and suck it into the firewall with the new screw.... I had a nut spin and had to cut the head off to get it out....stripped would be a much easier repair I think..... Good Luck

Ryan

drill and or hammer out the blind nut and replace it.

One of the biggest thing I had to overcome when I started building was the fear of cutting holes, your not gonna hurt the integrity of the ship, yank it out and replace

Well, that's fairly good advice. You might not want to approach this chore like a bull in a china shop. Tap it out would be a bit better idea than hammering it out. That firewall is only a piece of 1/4" ply (probably) and you can rip it out of the plane if you are to agressive with your repair. They are not china, but they are not iron either. You can break things if you go at to agressively. Be careful, and focus on taking out the blind nut and doing the least amount of damage (like no damage) in the process. It should come out fairly easily, but don't over do it either.

CGr.

Welcome to the forums, Juanico!

Pushing the nuts out carefully is the best you can do.
For that you could use the next size bolt.

I don't like blind nuts.
For the firewall, I prefer using regular nuts epoxied to the back of the firewall.
Sometimes, there is no enough room in the tank compartment to do so.

I live about 25 miles from you; just send me an e-mail if you need my help.

smaller screwdriver you gorilla....just kidding.....replacing the blind nuts is the way to go......unless you're absolutly terrified of tapping the blind out of the hole...you could try a longer screw and get through the blind nut....then secure it with a lock nut...I do that anyway to make sure I don't loosen a motor mount screw/bolt from vibration

If you use longer screws, just be careful that they don't interfere with the front of your fuel tank. This is one place you do not want 'shave weight' with added holes

I can actually answer this - YAY!!!!! Take a soldering iron and touch it to the blind nut for about 2 minutes.... The heat will soften the epoxy.....Then take your mount bolt and screw in just a little from the front...then gently hit with hammer one time. Should pop nut right out. Replace with another blind nut. When replacing - use 30 minute epoxy ( so you have time)...and dab just a little on the sides of the blindnut..... you can then try and place in hole ..or hold as you screw bolt in again to position it. When positioning...use your bolt with washer going through a small flat piece of hard wood, ply, whatever will hold the pressure..... Screw bolt all the way in tight, this will have the blind nut dig into the firewall and should hold. When removing bolt again to allow to dry....do it gently so the nut will not pop back out before the epoxy starts to hold.

Take your time to get your alignment correct. If you run out of time...and epoxy starts to harden....just start all over again. No biggie. If you only have 1 blind nut to work with....just drop it in acetone and let it sit for a while to break the epoxy down....dry it and start over.

Thanks for all the quick replies, I'm still at a crossroads, between pulling the blind nuts and replacing them, or leaving them in place and use longer screws and a nylon nut on other side. By the way, if using nylon nut do I still use locktite or not ?

Thanks again to you all.

PD. lnewqban thanks for the offer, I'm gonna see tomorrow if I solve it, if not, I'll be happyto accept yourhelp. By the way, where do you fly ? Delray or 45th street ?

no

No locktite...will not be required as the nylon becomes the lock

Problem solve in a very easy and unexpected way. The original screws were 20mm X4mm metric. I went american with 8-32 X 1" , and the screws locked in tight. Thanks to all you guys for the responses.
Maiden is tomorrow.