Dzus Repair

[dedrekon]

I have a couple of missing Dzus studs. The hole for one is worn away, but the other looks like it would still hold one in place. I assume I can rivet a patch where it's too worn to repair, but my question is: how do you attach Dzus studs? Are there special tools involved or is there a way to put these in at my shop?

Any help would be greatly appreciated. I did a Google search, but didn't come up with any concise Dzus installation stuff.

[Mark Julicher]

Re: Dzus Repair

dedrekon,

You guessed correctly, there is a special tool, actually a special tool set and one set for each size Dzus fastener.
Look in Aircraft Spruce catalog and see them. T-craft uses the number 5 Dzus so that is the size tool set you want.

The process is roughly: Put new grommet into hole, partially flare the grommet by pushing one of the Dzus tools into it, insert the quarter turn fastener into the partly flared grommet, smash grommet flat with Dzus tools which effectively causes the grommet to grab and retain the fastener.

Buy a few extra grommets and practice with scrap aluminum. It is fairly easy to drive the old fastener out of its grommet with the tools -- this shears the old gromment and destroys it, but the fastener itself is reuseable, so it is fairly cheap to practice setting fasteners before you risk some high dollar sheet metal.

Yes you can splice in a sheetmetal repair and put your fastener in the new metal if you need to. I have done exactly that with good results. The alternative would be to weld in a patch of sheet metal and I am not good enough with torch or tig to do that yet.

[jdoran]

Re: Dzus Repair

I made my own tool(s) by doing the following:

Poke the sleeve thru the hole in the cowling, (preformed side to the outside of the cowling) then "flare" the inner end of the sleeve using a 1/4" stove bolt with a tapered head. Place a washer between the nut and the preformed flat portion of the sleeve. Simply tighten the nut on the other end of the bolt with a wrench to start the flare using the head of the bolt. Flare it about 45 degrees. Remove the bolt at this point, and the partially flared sleeve should stay in the hole. Next, put the DZUS stud into the partially flared sleeve, and use a homemade bushing and a c-clamp to finish forming the sleeve around the DZUS fastener.

My "homemade" bushing was nothing but a 1/2" pipe plug I had laying around with a 5/16" hole drilled thru the center of it. The 5/16" hole fit a #5 DZUS fastener, but you can measure the diameter of the stud and drill that sized hole in your homemade bushing to fit it.

Let me know if you need some photos, it's kind of hard to describe.

John

[mhorowit]

Re: Dzus Repair

John - any pics you might have would be appreciated - Mike

[Dano"T"]

Re: Dzus Repair

John....Pictures would be great...I lost 2 Dzus fasteners and a grommet Sunday while on a cross country flight......I just ordered some AJ5-40 fasteners from Spruce and some grommets......the c-clips are neede to hold the Dzus into the cowling when released also...so I got some of those too. I just want to be able to squish a grommet on for a quick repair....I flew my plane to Baumann floats shop in New Richmond, WI to get the floats back on and I need to fix the cowling before we fly it.

[dedrekon]

Re: Dzus Repair

Anybody know what the size of the Dzus are in the BC12D cowling........they have so many sizes listed at Aircraft Spruce it's a bit confusing.

[Dano"T"]

Re: Dzus Repair

AJ5-40 - Fastener
GA5-312 - Grommets
SR5ss - C-clip

[dedrekon]

Re: Dzus Repair

Thanks Dan! I ordered some from Aircraft Spruce.....sure could use some pictures before they get here.

[NY86]

Re: Dzus Repair

.....sure could use some pictures before they get here.

Which, parts or tools?

BTW, if anyone needs AJ5-50 studs, I've got about a thousand of them...

[dedrekon]

Re: Dzus Repair

Great pictures...they do make it a lot clearer. I was trying to do it without buying MORE tools. I can hardly get in and out of the shop as it is.
John mentioned that he had fashioned his own and was going to post some pictures.

[jdoran]

Re: Dzus Repair

Here's a poor man's DZUS installation tool kit.


John

[NY86]

Re: Dzus Repair

Here's a poor man's DZUS installation tool kit.

Which is #1, 2, 3, and 4?



Seriously, do you just push on the head of the fastener with the ram of the C-clamp?

[Taylorcrafty]

These posts were very helpful in figuring out how to repair the dzus fasteners on my cowling.

This site has a bunch of great info as well for anyone else working on these: https://www.milspecproducts.com/z_sp...s__compatible_

They also sell the fasteners and tooling.

[astjp2]

If you have a hole worn through your cowling, rivet on a doubler INSIDE the cowl and use flush rivers to hold it in place. You also need to make sure that the spring tension is correct for a dzus to not come loose or fall out.