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crack in rudder skin

erich weaver

erich weaver

Well Known Member
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I found this small crack in my -7A rudder skin during a recent preflight inspection. I both called and emailed Vans to inquire about the appropriate degree of concern and a fix procedure, so got responses from two different people. The two responses were consistent in that neither believed it was of any serious concern, with no fix even being necessary, although one indicated I could stop drill and try and hide it with some proseal/micro as desired. Regarding the cause, the first response indicated such small cracks were not uncommon and likely due to prop blasts against the rudder, with the tear occuring where the relatively rigid structure of the rudder leading edge transitions to the remaining portion of the rudder that is relatively flexible. My email responder indicated the crack was likely due to insufficient rolling of the leading edge skin during the build.

Didnt recall seeing this type of crack before on the forum so thought I would pass the info along in light of the the recent SBs.

erich
 
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erich weaver said:
23vksq1.jpg


I found this small crack in my -7A rudder sking during a recent preflight inspection. I both called and emailed Vans to inquire about the appropriate degree of concern and a fix procedure, so got responses from two different people. The two responses were consistent in that neither believed it was of any serious concern, with no fix even being necessary, although one idnicated I could stop drill and try and hide it with some proseal/micro as desired. Regarding the cause, the first response indicated such small cracks were not uncommon and likely due to prop blasts against the rudder, with the tear occuring where the relatively rigid structure of the rudder leading edge transitions to the remaining portion of the rudder that is relatively flexible. My email responder indicated the crack was likely due to insufficient rolling of the leading edge skin during the build.

Didnt recall seeing this type of crack before on the forum so thought I would pass the info along in light of the the recent SBs.

erich
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This type of crack has been observed and discussed before and the most common belief is from insufficient/roll in the leading edge.

I had a crack in my trailing edge but that was as a result of another cause and although I was told ?it is of no serious concern and can be stop drilled? I opted for rebuilding another one since it is not that hard or expensive. Although I spend far more $$$ and effort to [match] paint the rudder and still did not come as perfect as I wanted.
Hine sight, I should have stayed with the same [original] rudder.
 
I have a similar crack in my -6 rudder a little higher up. I stop-drilled it with a small #50 bit and it hasn't changed in 6 years and 500 hours. Looks a little tacky,though...
 
Found a couple of these on my rudder the day I flew to the paint shop. We patched with some stick-on pieces of 0.016 Al (circles) before paint. No continued cracking (500+ hours later), so doesn't seem a structural issue. A common thought is that these occur due to flexing at the end of the stiffener, particularly if the stiffener was not attached with some proseal or silicone or similar material during assembly (which mine were not).

Greg
 
I had some of these on my 9A due to overdriving the stiffener rivets during the back riveting process. I read the instructions that said to make sure those last rivets were fully set so as to not interfere, and well, I drove them hard enough they were sticking out proud of the skins (YIKES). I got the pleasure of building a new rudder which never had any issues after that. I also wet set the stiffeners in proseal when I rebuilt them and put a blob at the end of each one to try and tie them in a bit to the spar. Not much help unless you are building a new one.
 
I have several on my rudder. No stop drill and they have not increased in size in 5 years and 400 hours.
 
plehrke said:
I have several on my rudder. No stop drill and they have not increased in size in 5 years and 400 hours.
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Nearly 15 years now (1200 hrs) for the cracks in my RV-6 rudder. I've watched them and they haven't changed since they first appeared when the plane was young. The cracks relieved the stress at the ends of the stiffeners and the rudder has been happy ever since.

I realize the rudder will have to be reskinned if/when I sell the plane but haven't gotten around to doing anything yet......maybe this will be the year reskinning perks to the top of the to-do list.
 
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Rudder cracks

I had lots of these cracks develop. I put aluminium 'speed tape' along the line of the stringers where the cracks were appearing.. seemed to help a little. Eventually decided to build a new rudder last year after reading about the C GNDY Rudder flutter accident..

I often use a lot of rudder to slow down (FP prop) and thought it might be the cause.. New rudder crack-free so far :)
 
One such crack early in the life of the airplane. I stop drilled it. It hasn't changed since and no more have shown up for the 13 years since the crack was first observed.
 
We have an RV4 at Jasper that has 4 cracks in his rudder all about an inch long and all stopped drilled. These appeared about 4 years ago and he has done nothing else. Rob told me this is a fairly common thing on 4's
Jack
 
Sounds like I have plenty of company although I cringe every time I see this thing. Think I might try a small patch using a circle of 0.016 like Greg suggested

Thanks all
Erich
 
Erich,
I would wait before adding a patch to your rudder. I had 3 cracks show up at different times about 500 hours ago. I stop drilled them, put some RTV in the holes, put a dab of paint to match and haven't seen another show up since then. I too purchased a new rudder kit and it is still in the box I think I will just include it in the sale of the plane when the time comes.
 
On my 9A I had a crack like this show up on both sides after someone elbowed my rudder that bent the lower trailing edge when parked at Oshkosh. Built a new rudder about 4 years ago and have never painted it since it has never gotten worse. Just fly it and check it regularly.
 
We're joining the rudder-crack club. These three cracks were tiny when we bought the plane (at ~340 hours).. We thought at first they were just a blemish in the paint at the rivets. But now (~450 hours) they've spread and it's clear the skin is cracking.

This makes sense, given the load is concentrated on the last rivet on the stiffener. But does anyone know why Van's doesn't have the stiffeners connect to the main rudder spar? That would allow most of the load to not be passed through the skin...

Given the responses on the forum, we'll stop drill these and monitor the condition. Maybe one day we can build a new rudder too.

Gotta say how much I love this forum! Always so helpful :)

Thanks all!
James.

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Rudder cracks

I too have 3 cracks on the rudder in area mentioned in other posts. They were there when I purchased the ship three years and 210 hrs ago....no change. In a post I read just after purchase, someone suggested putting a small piece of clear packing tape over them so I could see if it changed over time. I put a pencil mark at the ends of the cracks prior to putting the tape on no change to date. Some basic acro, and some Colordo mountain turbulence.
 
I have a couple of these cracks showing up on my HRII.

I'm wondering if the rudder can be rebuilt with new skins and stiffeners using the original spar.

Russ Werner
HRII
12 years/1000 hours
 
I am more curious about the theory of the cause being the lack of correct leading edge roll.
Did anybody get an explanation why the leading edge roll would cause it?
Is the assumption that the definition of an incorrect roll was when the transition from the spar web to the roll was not smooth and there was a crease?
 
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