Home > VansAirForceForums

-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.

Go Back   VAF Forums > Main > RV General Discussion/News
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Thread Tools Search this Thread Display Modes
Old 03-16-2020, 09:36 PM
blackbeard10's Avatar
blackbeard10 blackbeard10 is offline
Join Date: Sep 2007
Location: OH
Posts: 213
Default cracks in skin around rivets on rudder

During condition inspection I found these two cracks in the rudder skin on the right side. None visible on the left side and the rest of the tail showed no cracks either in the skins or structural members. My plan so far is to use MEK or acetone to remove all primer and paint around these two crack to better visualize the extent of the cracks. If they are limited to around .75 inch or 1 and are only over the ribs, I will drill stop holes and widen the crack lines with dental burr, apply fairing compound and repaint. 400 hours on my rv 4. Comments appreciated.
Mark Wyss
Madison WI
0 360 A1A Ellison throttle body
Trutrak Efis
Catto 3 Blade

Last edited by blackbeard10 : 03-16-2020 at 10:09 PM. Reason: photo adjust
Reply With Quote
Old 03-16-2020, 09:56 PM
blackbeard10's Avatar
blackbeard10 blackbeard10 is offline
Join Date: Sep 2007
Location: OH
Posts: 213
Default cracks in rudder skin photos


Well, can't get the freaking photos to post
Mark Wyss
Madison WI
0 360 A1A Ellison throttle body
Trutrak Efis
Catto 3 Blade

Last edited by blackbeard10 : 03-16-2020 at 10:06 PM.
Reply With Quote
Old 03-16-2020, 10:17 PM
Scott Hersha Scott Hersha is offline
Join Date: Jan 2005
Location: Cincinnati, OH
Posts: 2,012

Hey Mark! How?s it going (other than the cracks) ? What thickness is the skin? Original was .016, but yours is newer, so I assume .020. There were problems originally with elevator skin cracks at the trailing edge where the stiffener angles were riveted, and a fix was to add a dollop of RTV in that area on each stiffener trailing edge (which you already know about). I haven?t heard of that problem with the rudder, but it may be the same cause. Being that it?s on the right side, I wonder if it is in the same vicinity as a rudder trim wedge maybe on the left side of the rudder? Stop drilling and filling may work if the stress in that area is relieved by that. Cleaning it up with a dental tool first - good idea..... where did you get one of those?
RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
RV4/bought 2016/sold/2017
RV8/2018 built/Sold(sadly)
RV4/bought 2019 Flying
RV6/Used kit purchased 2021 building
Cincinnati, OH/KHAO
Reply With Quote
Old 03-16-2020, 10:20 PM
drill_and_buck's Avatar
drill_and_buck drill_and_buck is offline
Join Date: Feb 2005
Location: Bridgewater, MA - KPYM
Posts: 479

Hi Mark,
Cracking of the rudder skin is not uncommon on early RV-6 models that used .016 thickness skins for the rudder which could be similar to yours. However they have also showed up on RV-7s, 9s, .... The cracks often occur on the end rivet of the rudder stiffner. Suspected cause is preload + vibration, ..... Some just drill stops holes while others will take additional actions. You can search the archives for various approaches others have taken.

See this thread
Mike Draper
RV-8 N468RV
First Flight 11/13/2011
TMX0360, Dual Pmags, CS
Reply With Quote
Old 03-17-2020, 08:31 AM
Mel's Avatar
Mel Mel is offline
Join Date: Mar 2005
Location: Dallas area
Posts: 11,214

Keep in mind that the primary cause of these cracks is insufficient bending of the trailing edge. There are MANY .016" control surfaces that have been flying for over 25-30 years without cracks.
Mel Asberry, DAR since the last century. Over 1,000 certifications accomplished. Discount for Veterans, Law Enforcement, Fire Fighters.
EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
Reply With Quote
Old 03-17-2020, 08:43 AM
tsneidin tsneidin is offline
Join Date: Jul 2005
Posts: 119
Default My rv-9 developed cracks

After around 300 hours. I rebuilt the entire rudder and used proseal on all the stiffeners. I'm 300 hours since the rebuild and no signs of cracks returning.
Todd Neidinger
RV-9 Flying
Reply With Quote
Old 03-17-2020, 09:29 AM
JonJay's Avatar
JonJay JonJay is offline
Join Date: Jan 2007
Location: Battleground
Posts: 4,348

Stop drill at each end of the crack and keep an eye on it.
This should stop their migration. Once you are sure they are stabilized, you can fabricate a simple .016 patch, the size of a quarter or less, and glue them over the area with thinned proseal and paint. You won?t notice them.
I had one crack in my first 20 hours, then went 800 before my second one showed up, exactly like yours in exactly the same place. I pulled the patch on the one that occurred twelve years ago and it hadn?t changed. I am monitoring the second after stop drilling and may or may not patch.

The issue was well known when I built my rudder. I followed all the protocols in fabrication, trailing edge bend to reduce preload, RTV to tie stiffeners, etc...

If I get anymore, I will have to remain or rebuild. If I do, I will use .020.

However, as Mel says, lots of .016 rudders with no cracks on airplanes with high hours.
Smart People do Stupid things all the time. I know, I've seen me do'em.

RV6 - Builder/Flying
Bucker Jungmann
Fiat G.46 -(restoration in progress, if I have enough life left in me)
RV1 - Proud Pilot.
Reply With Quote
Old 03-17-2020, 01:28 PM
Dean Pichon Dean Pichon is offline
Join Date: May 2006
Posts: 555

The rudder on my -4 developed similar cracks after a few hundred hours in service, probably for the reasons previously noted. I stop-drilled the 0.016 skins and flew for a couple more years before a built a new rudder using .020 skin material. I bent more carefully and prosealed the stiffeners to the skin. Twelve years later, no cracks.

Now, I making new elevators using .020 skins. (For the same reason.)

Good luck,

Reply With Quote
Old 03-17-2020, 07:51 PM
AX-O's Avatar
AX-O AX-O is offline
Join Date: Jun 2005
Location: SoCal
Posts: 2,545

Mark, looks like something else is going on with that rudder.

There are creases and deformities around the lower rod end bearing (on the skin). Did the rudder hit the rudder stop hard due to wind?

I had a similar crack on one of the rivets around the elevator trim hinge. Drilled it and glued a piece of 020 over it. Worked great.
RV-4 fastback thread and Pics
VAF 2020 paid VAF 704
The information that I post is just that; information and my own personal experiences. You need to weigh out the pros and cons and make up your own mind/decisions. The pictures posted may not show the final stage or configuration. Build at your own risk. Further more, these are my opinions and not those of my employer.
Reply With Quote
Old 03-17-2020, 09:00 PM
TJCF16's Avatar
TJCF16 TJCF16 is offline
Join Date: Mar 2015
Location: Greenville SC
Posts: 189

I have the same cracks. Two rivets on rt side fwd last one in stiffener . I got a disposition from Van?s. Stoped drilled and have not seen anymore migration! I plan on patching with a 1 1/2round piece of aluminum and pro seal!
Tim Crouch
RV-9A N626TC
Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -6. The time now is 11:11 PM.

The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.