Crack in trim tab

Dgamble · #1 05-03-2006, 05:45 AM

A small crack is developing in my trim tab, coming off the corner where the control arm joins the tab.

What are my options here? I can easily stop drill it and monitor it to ensure that it doesn't grow, but I'd like to consider longer term options. Two come to mind: build a new trim tab, or try to re-skin the one I have.

I've seen the tab skin in Van's catalog, so that part is easy enough to get, but are the other parts equally easy to get? Is it likely that I can get the old skin off without destroying the underlying structure?

And what are the chances of this being a recurring problem? I there something wrong with the way the current one is built/mounted/aligned?

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jcoloccia · #2 05-03-2006, 06:08 AM

If it's anything like the -7 (which from looking at other builder's websites it is) there is no underlying structure. It's just a skin with a spar in front.

Maybe yours is from a really old kit but all the trim tabs I've seen have the horn mounted on the bottom. I would be shocked if Vans had ever designed the horn to be mounted to the side like that....cracks would be inevitable, I think.

Anyhow, it'd probably take you a week to build the trim tab yourself if you have no experience. You could give it to an experienced builder and he could crank it out in a day.

I'll also mention that it looks like the right end of the hinge is tweaked up a bit (a side affect of how the pin is safety wired). May not be a big deal but it certainly doesn't help to have that stress right at the edge of a sheet. Maybe that contributed to the crack.

lrfrey · #3 05-03-2006, 07:10 AM

Yep, pretty simple structure... but the reason the skin is in the catalogue is it is a PITA to build, and a lot of folks build more than one!

If you want to rebuild it, it's possible to drill it out and reskin it, but I'd opt for the skin, spar, hinge and horn and start over. The parts are all in the "LIST" on Van's web.

Now, having said that, if you have no previous metal/riveting experience, this "ain't the part to learn on".

Stop drill it and watch it ... IMHO

Larry

rv6rick · #4 05-03-2006, 07:31 AM

Hi Dave,
The older trim tabs had the horn on the side. You don't have 'something special.

Step 1 - Call Vans and order the new one...it's something like $20 to $25 bucks. If they no longer have the 'side tab' then just use your old one or whip out a new on......this will keep the cable pass through hole aligned.

Step 2 - Stop drill the crack and keep flying.....check it on preflight.

Step 3 - Whip out a new trim tab when you're new one arrives, making sure to align the new hinge with the old hinge on the elevator. Paint it and you're done.

I repectfully disagree with the other replies.......this IS the part that you learn on as a new builder......it's a piece of cake and only cost $20 bucks if mess it up. Also....it doesn't take a week or even a day to make one. Bring it over my place and we'll whip it out in an hour and a half....including lunch.

Where were you at the clinic dude??

Rick Gray in Ohio at the Buffalo Farm

Mel · #5 05-03-2006, 07:32 AM

Dave,
If you decide to build a new tab, you might try what I did. Instead of folding the end, cut it square and make an "end rib". This look neater and is easier to do. I also set the end rib in by the thickness of the horn so that the horn is flush with the skin. Been flying for 13 years with no cracks anywhere. I'll try to get out and take a pic or 2 and send to you.
Mel...DAR

sf3543 · #6 05-03-2006, 07:36 AM

The crack you have shown is a problem that surfaced with RV6 trim tabs that were built according to plans back in the 90s. I had the same thing happen to me. VAN came up with a fix, which was detailed in the RVator back around 1998 or 1999. You have to rebuild the tab, if it is cracked, and add a piece of .040 (?) metal that attaches to the spar on the back and wraps around the rib where the horn is attached. This stiffens up the entire structure and oui la...no more cracks. You can also get the thicker trim tab skin, which also helps, but if you use the same horn, you still need to add the fix.

jcoloccia · #7 05-03-2006, 07:38 AM

Quote:

Originally Posted by rv6rick

Also....it doesn't take a week or even a day to make one. Bring it over my place and we'll whip it out in an hour and a half....including lunch.

Lol....it only took me 5 minutes to screw up my first one (clamp slipped and I demolished the trailing edge).

Dgamble · #8 05-03-2006, 08:16 AM

Where were you at the clinic dude??

Flying with the daughter:

http://n466pg.blogspot.com/2006/04/g...rove-city.html

I would love to have come down if only to take pictures, but the days when I can get Egg to fly with me are few and far between. As it was, I had to bribe her with a trip to the outlet mall at Grove City, PA. We monitored button 5 on the way - sounded like fun! BTW, does anyone ever ask W-P ops to cite their authority to try to kick you off that freq? Just curious about that.

Next year for sure!

Dgamble · #9 05-03-2006, 08:21 AM

I told my A&P that's doing my condition inspection that I'd have an answer to this in 15 minutes. He commented that he'd be lucky to get an answer from Cessna about something like this in 15 days, if at all!

I'm going to monitor it, and I think a stop drill will probably be enough for awhile, but I think I will also build a new one just for the experience. I'm in A&P school (coincidentally, I'm in sheet metal class this quarter, and tonight we're talking about skin repairs), and I want to build a -10, so it would be silly to pass on a learning experience like this!

Dgamble · #10 05-03-2006, 09:33 AM

Do you think I can get away with ordering the pre-punched skin?

Here's the shopping list so far:

TRIM TAB SPAR
E-607PP $4.41 $4.41

Prepunched 0.016 elevator trim tab skin for RV-6
E-619PP $10.00 $10.00

TRIM TAB HORN
AS3-063X3X3 $1.32 $1.32

This is probably the bottom mount horn, but I think I can recover the existing right side horn. Not sure I want to, though.