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  #1  
Old 05-07-2021, 09:16 PM
Walt's Avatar
Walt Walt is offline
 
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Location: Dallas/Ft Worth, TX
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Default Horiz Stab cracks/repairs: Don't do this...

If you find cracks on the horizontal web (ref SB 14-01-31) please do the repair recommended by Van's.
This aircraft is going to have to have a new horizonal stab made now because of the botched repair job.
The repair parts and install instructions (video) for this "Bracket mod" do not comply with Van's SB intent nor do they have any approval from Van's engineering. (it's also getting new vertical attach fitting).
It would have been much easier/cost effective to do the SB mod than it will be to build this guy a new stab.
I guess the guy who did this repair also preferred the looks of the all thread hex head fasteners more than AN hardware.
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Last edited by Walt : 05-08-2021 at 08:06 AM.
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  #2  
Old 05-08-2021, 07:52 AM
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Carlos151 Carlos151 is offline
 
Join Date: Jan 2008
Location: Lebanon, TN
Posts: 403
Default Be afraid, be very afraid

These are some scary pictures
Reminds me of the puzzle pictures, how many mistakes can you find?
Random hardware, edge distances, bolt lengths, spacers, etc.
I guess they were worried about cracks. With what you can see in these pictures, I would be worried too and wondering about the rest of the aircraft.
At least the torque seal looks good
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  #3  
Old 05-08-2021, 09:33 AM
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Snowflake Snowflake is offline
 
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Quote:
Originally Posted by Carlos151 View Post
With what you can see in these pictures, I would be worried too and wondering about the rest of the aircraft.
I'm not so sure about that. The visible riveting job looks fine, although hard to see in the small photos. These two questionable mods are clearly not part of the original build.

Aftermarket mods that don't affect structure are one thing. These were scary when they were first announced, and are no less scary now.
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  #4  
Old 05-08-2021, 10:33 AM
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Carlos151 Carlos151 is offline
 
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Quote:
Originally Posted by Snowflake View Post
I'm not so sure about that. The visible riveting job looks fine, although hard to see in the small photos. These two questionable mods are clearly not part of the original build.

Aftermarket mods that don't affect structure are one thing. These were scary when they were first announced, and are no less scary now.
Not so sure about that. I agree, it's hard to see with these small pictures, but even so, I see a few over driven rivets, spar spacers that were not fitted properly, rough edge finishes, an extra hole between two bolt heads that has nothing in it (not sure if it's supposed to or not), a bolt head that appears to have been drilled on the top or it might be another hole behind the bolt head (might have happened during the mod install), nuts installed with maybe a half a thread visible, broken down nyloc nuts. There's likely more, that's all I'm saying.

Totally agree though that most of the "damage" was caused with the mod install.
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  #5  
Old 05-08-2021, 11:40 AM
David Paule David Paule is offline
 
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You can click on the photos and get a larger photo.

Dave
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  #6  
Old 05-08-2021, 01:54 PM
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MacCool MacCool is offline
 
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Location: central Minnesota
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Default

Quote:
Originally Posted by Walt View Post
If you find cracks on the horizontal web (ref SB 14-01-31) please do the repair recommended by Van's.
This aircraft is going to have to have a new horizonal stab made now because of the botched repair job.
The repair parts and install instructions (video) for this "Bracket mod" do not comply with Van's SB intent nor do they have any approval from Van's engineering. (it's also getting new vertical attach fitting).
It would have been much easier/cost effective to do the SB mod than it will be to build this guy a new stab.
I guess the guy who did this repair also preferred the looks of the all thread hex head fasteners more than AN hardware.
Walt, are you saying that the aftermarket "horizontal stab bracket mod" is fundamentally and conceptually bad, or that the one pictured was installed badly? I'm not a builder, and the SB 14-01-31 doesn't affect me so I'm not clear on the issues, but I'm interested in your opinion regarding the perceived problems with this aftermarket mod.
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  #7  
Old 05-08-2021, 02:30 PM
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Carlos151 Carlos151 is offline
 
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Quote:
Originally Posted by David Paule View Post
You can click on the photos and get a larger photo.

Dave
Sure can, but at less than 150KB per picture, they are still Lo Res no matter how many times you click on them.
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  #8  
Old 05-08-2021, 02:48 PM
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Walt Walt is offline
 
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Quote:
Originally Posted by MacCool View Post
Walt, are you saying that the aftermarket "horizontal stab bracket mod" is fundamentally and conceptually bad, or that the one pictured was installed badly? I'm not a builder, and the SB 14-01-31 doesn't affect me so I'm not clear on the issues, but I'm interested in your opinion regarding the perceived problems with this aftermarket mod.
In my opinion the 'mod' is worse than nothing as it is based solely on eyeball engineering and makes people think that it has some real value to improve the strength of the Horiz, there is absolutely no engineering data for that claim. The fact that this particular example was installed so poorly it ruined the front spar and cannot be repaired (or simpler to build a new one).

I've been involved in some major structure repairs for a very long time, and I've learned to respect the things engineers do that I cannot see. I do know merely attaching a stronger piece of material to a section of structure to "reinforce" it, unless properly designed just moves the stress area to another perhaps weaker location which may make things more likely to fail.

I can eyeball a lot of repairs using methods in 43-13 but when it comes to primary structure like spars that one goes to eng for approval.
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EXP Aircraft Services LLC
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Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
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  #9  
Old 05-08-2021, 02:55 PM
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Walt Walt is offline
 
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Quote:
Originally Posted by BillL View Post
Installed badly.

1. Rivets were replaced with 10-32 stainless with threads to the head, this means a thread is carrying the shear loads of the HS.

We can not see the additional fasteners behind the rib. Likely the same. as #1.

As a builder - stay with the plans or know exactly, precisely what you are doing.
FYI, the ASplat 'mod' has no fasteners OB of the rib (unlike the Van's SB repair which carries the reinforcement further out, hence the difficulty of installing the Van's repair compared to this mod).
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Walt Aronow, DFW, TX (52F)

EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 2000+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
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  #10  
Old 05-08-2021, 06:36 PM
Rallylancer122 Rallylancer122 is offline
 
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Default

I "re-sparred" a stab after a someone botched the sb. It wasn't as bad you might think. I think I ended up using about 4 cherry rivets and was able to finish the rest back to stock. The parts were a lot cheaper than an entire stab kit. I wouldn't hesitate to do it again.
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