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  #11  
Old 02-20-2018, 09:11 AM
337_Driver 337_Driver is offline
 
Join Date: Feb 2018
Location: Youngsville, NC
Posts: 23
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The damage is from a significant ground loop after a hard landing. The wings were replaced. It was 20+ years ago. If he and I can agree on a price I'm still strongly considering the airplane.
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  #12  
Old 02-20-2018, 09:32 AM
RV6_flyer's Avatar
RV6_flyer RV6_flyer is offline
 
Join Date: Jan 2005
Location: NC25
Posts: 2,992
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Quote:
Originally Posted by Dayton Murdock View Post
What is flexing to cause this to happen. Until that is resolved this deformation will occur again.
There was a design change of the steel weldment in the four corners of the firewall longeron attachment located in the cockpit. (Wd-402L, Wd-402R, Wd-403L, and Wd-403R) It deals with early RV-4s. Later kits were shipped with an improved part. I thought there was a SB for it but cannot find it. The change was published in the early RVators. If you really want to know more, I will dig through my early paper copies of the RVator and email it to you.

Google search found this.


"Engine Mount Bracket Reinforcement"
"[1988]"
"Several RV-4 pilots have reported cracking failure of the engine mount brackets (WD-402 & 403) in the forward fuselage. Usually this has resulted from continued operation from rough airstrips or one or more extremely hard landings. Regardless, these brackets seem to be the structural Achilles Heel of the RV-4 airframe."
"Some time ago, we altered the bracket design by increasing the thickness of the attachment arms from .050 to .065". However, many RV-4s now flying have the .050 brackets. We have developed a couple of relatively simple mods which can be added during or after construction."
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NC25 RV-6
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Building RV-8 S/N: 80012

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Last edited by RV6_flyer : 02-20-2018 at 09:43 AM. Reason: add link and quoted text
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  #13  
Old 02-20-2018, 05:02 PM
designerX designerX is offline
 
Join Date: Sep 2005
Posts: 145
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Quote:
Originally Posted by RV6_flyer View Post
There was a design change of the steel weldment in the four corners of the firewall longeron attachment located in the cockpit. (Wd-402L, Wd-402R, Wd-403L, and Wd-403R) It deals with early RV-4s. Later kits were shipped with an improved part. I thought there was a SB for it but cannot find it. The change was published in the early RVators. If you really want to know more, I will dig through my early paper copies of the RVator and email it to you.

Google search found this.


"Engine Mount Bracket Reinforcement"
"[1988]"
"Several RV-4 pilots have reported cracking failure of the engine mount brackets (WD-402 & 403) in the forward fuselage. Usually this has resulted from continued operation from rough airstrips or one or more extremely hard landings. Regardless, these brackets seem to be the structural Achilles Heel of the RV-4 airframe."
"Some time ago, we altered the bracket design by increasing the thickness of the attachment arms from .050 to .065". However, many RV-4s now flying have the .050 brackets. We have developed a couple of relatively simple mods which can be added during or after construction."

As mentioned in the previous posts the original poster is asking about the footwell deformation which is NOT a weldment crack. This is a deformation of the stainless footwell due to a hard landing (or ground loop) which is a different issue. If the price and craftsmanship are right and there are no other signs of damage around the gear intersection, motor mount and no weldment cracks then buy it and fly it!
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RV-8 slow build fuselage w/showplanes fastback
RV-4 (bought flying)

Last edited by designerX : 02-20-2018 at 05:04 PM.
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  #14  
Old 02-21-2018, 10:54 AM
Sylvester Sylvester is offline
 
Join Date: Mar 2017
Location: Uk
Posts: 8
Default Footwell

See the other post on this page entitled Firewall wrinkle. I think it's important to squash the heavy landing/grounloop theory. It could cause the problem, but I had the cracks without either. It's a structural design problem, which can be cured, I hope, with gussets to brace the 3/4 x 3/4 verticals as per the RV7. Very complex loads in those front corners and not enough rigidity. Build accuracy helps too.
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