Third annual condition inspection

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svanarts
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Third annual condition inspection

Post by svanarts »

I started my third annual condition inspection today and already ran into one big but common squawk. Upon inspecting my left hand elevator, a friend who was helping me noticed a crack in the trailing edge. I stopped drilled the crack and am going to fill in with JB Weld. I now have the opportunity to build again. I'm going to rebuild both elevators and this time I'm going to put electric trim in rather than manual. I'll probably save a pound or two this way.

If you're still bulding your -4 the way I've heard to avoid this common cracking problem is 1) build from a later kit that has thicker skins, and 2 put a bead of RTV in the trailing edge once you've got your edge bent.

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Post by Spike »

Well, at least you get to build something again without the wife getting upset. :mrgreen:

I believe this is why they probably went to the two the "bend in the front" skins on the later models. I have also heard that the RTV or Proseal will help fix the problem. Get us a picture when you get a chance.

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Post by captain_john »

Scott, I too have heard that the 0.020" (thicker) control surfaces are the beefier trick for the dash fours. Reliability and performance over time is signifcantly increased. Some have argued that it loses some feel or feedback to the stick. I dunno, I am an idiot.

:P

I would give it a try too. Sounds like a new W&B would be in order for you too.

We need PICTURES!!!

:mrgreen: CJ
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Post by svanarts »

I tried to take some pictures today but the sunny weather just didn't make for good photos. I'll take some this week when I go to put some temporary crack patch (JB Weld) in to hold it together while I order and build new tailfeathers.

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Post by aerial »

Apparently this is a common problem with the .016 tail skins in the 4. A gentleman from Eureka, CA who owns a 4 had his rudder rebuilt this last year with the same cracks in the trailing edge. Apparently it's caused by vibration. I wonder if you could put a rocket control surface on a 4, or if need the whole tail. It might be worth giving Harmon a call in Bakersfield, I know they beef-em :bang: up. When I took a ride in Rob's 180hp CS propped RV4 in Oregon, It was right after I had flown in Van's RV-9 160hp with the 3 blade MT prop. The 9 was so smooth it makes me think I want a MT prop. But then by the time you are ready to hang the prop you wallet is getting so thin it would be easy to go cheaper.
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Post by captain_john »

No need to get Harmon involved. Van has his own fix with the 0.020" skins. The rumor is that it does the trick. The 0.020" skins are what we have on all kits after the -4's conception. I wonder what the -12 will have?

Hmmmmm...

:roll: CJ
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More squawks annual inspection squawks

Post by svanarts »

For the problem with the tail, I've ordered new elevator skins (.020) and all the stuff to make new elevators with electric trim. I'm looking at this as an opportunity!

Okay, more annual inspection items. The left main gear leg has a little play or wobble in it. When I removed the tires to repack the wheel bearings I found that I could twist the gear leag in it's socket by pushing the axle fore and aft. Probably about 1/16" - 1/8" of movement there.

I've also found some cracking on the top left wing skin right at the rear spar rivet line just outboard of where passengers step. Looks like some errant feet have caused this problem. Most of those feet were probably mine.

I also found that the safety wire that is holding the bottom of the engine baffles together has rubbed through an oil return tube causing oil pukage. I have to replace that line and also figure out how to keep the safety wire from rubbing on it.

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Post by svanarts »

Okay, I got the official word from Vans:

> Hello,
> I have a couple of concerns about some items that came up during my
> third annual condition inspection. Item number 1 is that some
> cracking has started to occur along the left wing top skin / rear spar
> rivet line. Cracks have formed around 3 rivets on the top skin just
> outboard of the reinforcing plate that you step on. I left my
> drawings at the hangar so I apologize for not having part numbers but
> I'm sure you know what I'm talking about. My assumption at this point
> is that this was caused by carless feet. My question is can this be
> repaired and how can it be repaired? Is replacing the inboard top
> skin my only option?

It's the only option to get rid of the cracks, but if you stop drill them
(don't drill into the spar though) it would be OK to leave them, and
they may not spread any further.

>
> Item number 2 involves the right hand main gear leg. When I had the
> wheel off today I noted that the axle can move fore and aft about 1/16
> - 1/8 inch. The bolt at the top of the gear leg seems to move with
> the gear leg. Is this a concern and if so what are my repair options?
>

It probably won't matter with that amount of movement, but it is likely
to get worse over time, sooner or later you will ned to fix it. You can
ream the hole out to 3/8, which will probably take care of it at this
stage by making the hole in the mount round again; it is most likely
slightly oval. Alternatively, you could weld a patch over the holes in
the mount and redo the hole to 5/16 and avoid enlarging it, if the
hole in the gear leg itself is still round.

Vans

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Post by Dan A »

I think I would drill it out to 3/8 and put the bigger bolt in it. That will make it stronger.
Dan

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Third annual condition inspection

Post by svanarts »

That's what I'm going to do. Much much easier than pulling the engine so I can weld on a patch.
I'm still debating what to do about the cracks in the wings skin. Whether to stop-drill and then
bondo over them or to put a doubler skin on top of the cracked area.

Feeling much better now!

--- RB Lists - RV4 <support@rivetbangers.com> wrote:

> I think I would drill it out to 3/8 and put the bigger bolt in it. That will make it stronger.
> Dan
> _________________________________________________________
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Post by svanarts »

One more update on the ol' annual. The wobbly gear wasn't as bad as I thought. I had somone with better eyes double-check me and told me I was nuts. It wasn't moving as much as I thought it was. I did find that the nuts were loose on the bolts that go through the gear leg sockets on the engine mount.

As for the wing I did buy another top skin. Right now I'm debating on whether to drill out the whole top skin or to just slap another skin on top as a doubler. I'm leaning toward drilling out all the rivets underneath the wing walk doubler, then drilling out rivets to the next wing rib. I could then add another rib or two for strength, extend the wing walk doubler out over the added ribs, then rivet the stop-drilled, cracked skin back down along with another skin on top. This would give me a veritable dance floor on the wing and wouldn't look TOO wierd.

Also did some tightening of the oil return lines, bought some new spark plugs, and ordered a Bell tailwheel fork. Nice unit and I like what it does for ground clearance at the tailwheel. Yeah you Van's tailwheel types know what I'm talking about.

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Post by captain_john »

Can we get a pic of the wing skin crack?

:oops: CJ
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Third annual condition inspection

Post by svanarts »

Sure, I’ll be out there in the morning.  I’ll try to snap a picture then.
 

From: RB Lists - RV4 [mailto:support@rivetbangers.com]
Sent: Tuesday, March 14, 2006 8:25 PM
To: rv4@rivetbangers.com
Subject: Third annual condition inspection

 
Can we get a pic of the wing skin crack?

ImageCJ




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svanarts
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Post by svanarts »

The much requested picture of wing skin cracking. This is just outboard of the wing walk reinforcing plate, just fore of the rear spar.

Image

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Post by captain_john »

Yup! Them are cracks!

:| Not that I doubted you, I just wanted to see what you were talking about exactly.

Do you have any insight as to why they appeared?

:? CJ
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Post by svanarts »

They appeared because I didn't listen to my gut and extend the wing walk out one more rib like I thought about doing. Mostly it came from careless passengers and short fat pilots not being careful about where they step.

Live and learn I guess. :bang:

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Post by captain_john »

How many ribs does it extend out, Four?

Is the -4 WW area smaller than the bigger winged variants?

...just wanna learn from you.

:roll: CJ
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Post by Spike »

Scott, what is the orientation of that picture? Ist it looking towards the fuse, or away from the fuse?
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Post by svanarts »

The wing walk only extends out to the 2nd wing rib counting from the root wing rib (and not counting the extra ribs added underneath the walk). Really should have extended it.

The orientaion of the picture is standing directly behind the left flap, looking forward. What you are looking at is the rear most row of rivets, between the 2nd and 3rd rib (using the above rib counting method.) I think on the 6/7 it goes out a rib bay and a half vs only one bay on the 4.

If I were building a plane I would take the wing walk doubler all the way to the second rib. Of course also adding the intermediate ribs to set the doubler on. Would make for a little extra riveting and a little added weight but might make for a more rugged wing.

Legal disclaimer: That is only my opinion and I'm not advising anyone else to do the above. :roll:

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Post by aerial »

captain_john wrote:Yup! Them are cracks! ...Do you have any insight as to why they appeared?

:? CJ
I'd like to know how he wing walks.

1) Puts on his aerodynamic leotards and parachute
2) Fires up the RV4 and climbs to 1500 ft. minimun aerobatic altitude.
3) Put's it on autopilot.
4) Walks out on the wing? :bow:
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