crack in rudder skin

[erich weaver]

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

[Bavafa]

Originally Posted by erich weaver

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

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.

[rvsxer]

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...

[Mike S]

Seen that in a few 6's, stop drill and fly ----- were it mine.

[Greg Arehart]

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

[akarmy]

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.

[plehrke]

I have several on my rudder. No stop drill and they have not increased in size in 5 years and 400 hours.

[Sam Buchanan]

Originally Posted by plehrke

I have several on my rudder. No stop drill and they have not increased in size in 5 years and 400 hours.

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.

[DeltaRomeo]

I have 'em too.

Stop drilled and monitored (flying for twelve years).

[Hum]

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 :-)