Flush Patches in Difficult Areas

[HarvardIV]

Hi Folks:

No this isn't about kicking smoking.. Wondering if any of you have had any experience w/ flush patches/ Specificly, I've got an owie in the middle of the wing, and it's at least 5 ft from the nearest inspection panel. My arms aren't 5 ft long, so I need a long bucking bar. Question is, have any of you ever had to do this type of repair, and how did you do it? Considering the distance is so far, I wonder if the rivet will even get a good flattening with the bar.

Also, getting the dimple dies in there must be an art in itself, let's hear it, pleeeaasse.

[Cvairwerks]

Cherry-locs or put in a ring doubler with nutplates are a couple of methods.

[HarvardIV]

Hi cvairworks:

You wrote:

Cherry-locs or put in a ring doubler with nutplates are a couple of methods

Ok, are you a depot level mechanic for Lockheed Martin? Anyway, thanks. Can you elaborate a little bit. I'm not sure of what you are suggesting?

Thanks,

Chris

[Dan K]

Chris,

Cherries are blind rivets...nothing overly technical here. Craig's probably a little surprised you never used them before.

Have a look here:

http://www.gen-aircraft-hardware.com/te ... ename=cmax

Now go and ask your favorite A&P or IA where he/she buys them. When in doubt there's always Aircraft Spruce & Specialty.

[HarvardIV]

I know what cherries are, but just included everything in the question.

[Cvairwerks]

Sorry to have shorthanded my answer too much Chris. What I meant is that you could use standard riveting methods to install the doublers that will be required to support the patch. With this, you have two options to install the patch itself....either use Cherries ( aka self plugging structural grade blind rivets) which will make the patch a permanent panel piece, or drill the patch for appropriate sized and quantity of structural screws and use nutplates riveted to the doublers. This would make it essenitally an inspection panel.

Spent about 5 years as a heavy structure mechanic and 7 years as a Flight Test Instrment Enginer and for the last 3 a Field and Service Mechanic on F-16's, in addition I did contract mechanic work for a couple of FBO's from 1981 until 2002 doing mostl warbird work.

One of the best references you can get for repair work Chris, is to find a copy of the structural repair manual for the 6. It will have a tremendous amount of information that will be well worth the cost of a copy. This is to supplement AC 43-13.

Hope this makes things a little clearer.....

[HarvardIV]

One of the best references you can get for repair work Chris, is to find a copy of the structural repair manual for the 6. It will have a tremendous amount of information that will be well worth the cost of a copy. This is to supplement AC 43-13.

Hi Cvairworks:

No need to apologize. Anyway, I gave you too much simplified information. My flush patch is per the T-6 structural repair manual, and that manual doesn't talk about converting to insp. panel on the wings. I think that may only be appropriate in non load bearing areas. For example, I found these in the cowling where a repair was made. I see you point, that with a insp. panel, you could at least get the dimple dies in, and the bucking bar. For this case, it looks like it would have to be a long bucking bar.

[krlang]

Hey,
wasnt there a link to a copy of the AC 43.13 not to long ago?
i thought i saw it here a week or two back.

[HarvardIV]

Hi krlang:

Yeah I posted it. My question isn't about knowledge of specs, but a question of technique. Clearly, technique is more of the art of it.

Last edited by HarvardIV on Mon May 30, 2005 9:44 pm, edited 1 time in total.

[RMAllnutt]

Just out of curiosity... if the area is so difficult to reach, how did they put the skin on in the first place? I assume they riveted it in like most aircraft of the era. I doubt a super long bucking bar would be effective unless you had a way to apply real force against it... and there'd be no way to check the bucked ends either. Sounds like a real connundrum Chris... are there any photographs around of T-6 wings under construction? Let us know what you find out. All the best. Richard

[Glenn Wegman]

Chris,

There is about a 6" to 8" wide close out strip running the length of the wing on the lower side. You drill that off from the tip inboard until you get to the area you need to access and then rivet it back in place after your repair. It's called a close out strip because it's just that!

Before you get too carried away, you should take a real good look at all of the ribs in the wings as they are subject to corrosion.

Glenn

[HarvardIV]

Hi Glenn:

The wing is good, no corrosion due to the heavy primer C.C.F. put in. Thanks for the ideas! BTW, navions and T-6s both seem to have a lot of hard to reach areas for riveting. Unless someone tries deriveting the whole panel line in the skin like you mentioned.

[HarvardIV]

Hi Richard:

Sounds like a real connundrum Chris... are there any photographs around of T-6 wings under construction? Let us know what you find out. All the best. Richard

Yes it is:

Here are photos of what we're dealing with:

http://community.webshots.com/album/357478903uJWfOg

Look at the series of photos called Mid_Wing, especially the first one.

Anyway, I mesed up the paint on one of the repairs, so you don't give me a hard time..

[bdk]

By the time you patch 2 or 3 holes in a skin it is usually faster (and better looking) if you just replace that entire skin. I replaced 3 skins on one of my wings due to storage rash (dents and small punctures) and probably had less than 40 hours into it. Unbutton the closeout strip and do one skin start to finish at a time to keep things in alignment.

You'll have a couple hundred dollars in sheet metal and rivets and have to find an experienced rivet bucker, but the results will be well worth the effort in my opinion.

[HarvardIV]

Hi BDK:

That might be a better idea. I kind of felt that reskinning would be a lot of work, but after hearing what you say maybe I should do it. Where's the best place to buy 2024 T-3 AL?