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  #21  
Old 11-23-2010, 08:43 PM
jersey jersey is offline
 
Join Date: May 2010
Location: Wharton, Texas
Posts: 122
Default Modify Cowling

This is a serious problem!!!!!

Found upper left and lower left bolts finger tight. I removed all bolts and reinstalled with locktite blue. Cut a section of the cowl out to access the upper left. Reinstalled the cut out with nut plates and aluminum tabs for future inspections. I don't fully trust it yet. If anybody is interested, I will be glad to send photos via email.

Gary
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  #22  
Old 11-23-2010, 09:03 PM
JohnF JohnF is offline
 
Join Date: Jan 2005
Posts: 458
Default Cut Out Photo

Gary, would you consider posting photo of how you make the 'cover' over the cutout that you make to inspect that one awkward to get at bolt? thanks
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  #23  
Old 11-23-2010, 09:46 PM
MartySantic's Avatar
MartySantic MartySantic is offline
 
Join Date: Apr 2008
Location: Davenport, IA
Posts: 1,369
Default

Quote:
Originally Posted by jersey View Post
This is a serious problem!!!!!

Found upper left and lower left bolts finger tight. I removed all bolts and reinstalled with locktite blue. Cut a section of the cowl out to access the upper left. Reinstalled the cut out with nut plates and aluminum tabs for future inspections. I don't fully trust it yet. If anybody is interested, I will be glad to send photos via email.

Gary
You better believe this is a SERIOUS problem. This issue is more than 1 week OLD and the only notification to those that have flying RV-12s has been via this website. This is indeed a SAFETY of FLIGHT issue, as mentioned in the initial post, and notification to ALL RV-12 owners HAS NOT but should have been made by now. Many have found at least 1 capscrew loose. At least three or more have been flying with 2 of the 4 capscrews loose or missing.

A periodic inspection is NOT an acceptable solution because the condition has been discovered between the required 100 hour ROTAX inspection points. As such, the required inspection MUST not be counted on, a critical situation may develop between the inspection points!!

Statistics dictate this is indeed a major problem. There are NOT that many RV-12s flying!

IMHO, notification to all is much more important rather than trying to find a solution and issuing the notification concurrently with the solution. We can try to notify all via this website, but, Van's has the complete list of RV-12 owners.

Please continue to report your findings to Van's at:

engineering@vansaircraft.com
with "SAFETY ALERT" in the Subject Line
__________________
Marty Santic ----- W9EAA
RV-12 N128MS ----- Now Flying
My RV-12 Build Log - http://www.martysrv12.blogspot.com/
Davenport, IA

Last edited by MartySantic : 11-23-2010 at 11:39 PM.
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  #24  
Old 11-24-2010, 06:23 AM
LIMA HOTEL LIMA HOTEL is offline
 
Join Date: Apr 2009
Location: Jackson MI
Posts: 71
Default

I think the best solution for this problem would be to use the same kind of lock washers under the engine mount cap screws as we use under the prop attach bolts. Lets see what Van's comes up with.
Larry

Last edited by LIMA HOTEL : 11-24-2010 at 06:29 AM.
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  #25  
Old 11-24-2010, 07:01 AM
okiejohn okiejohn is offline
 
Join Date: Jun 2008
Location: Oklahoma City
Posts: 74
Default Suggestions

I tightened the bolts at 25 hours and at nearly 100 hours I had 3 bolts loose.
Yes, I torqued them and i checked them at the 25 hour oil change, but not the inaccessible one. I erroneously assumed if it was covered up, it meant that access was not required therefore it would stay tight.

I think if you are getting ready to rtv your cooling shroud down, you should either:
1: wait for Vans to come up with a fix
2:moto- tool a slot that you can get a balldriver into to get to the left top screw. Then fiberglass a trough in so you can still get to the screw without leaking air.

If you wait till you get your engine in about the best you can do is rtv an aluminum cover.

I theorise that the tough steel of the engine mount might be as hard as the lockwashers and they don't get a good bite. Van's is so far against the blue medium strength locktite, but the technician at LEAF said it would work good and he recomended it. Without locktite, you need a short inspection interval.

I am not negative about this. With 400 RV-12s flying soon, we will be the largest fleet of new small airplanes, and any safety issues will be communicated on VAF.
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  #26  
Old 11-24-2010, 07:23 AM
jersey jersey is offline
 
Join Date: May 2010
Location: Wharton, Texas
Posts: 122
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John I think your right about the lock washers not performing. I noticed that the engine mounting bracket arm was flexing slightly when I was aligning the bolts. Although they firmed up when I tightened the bolts to the engine it would seem that they shouldn't rely solely on the engine case for rigidity. This is a high speed, high compression engine. It seems to me that a significant amount of energy retention would be concentrating where the brackets clamp to the engine. I'm probably over-analyzing. Hopefully Vans engineers will get back to us soon. In the meantime I will continue to inspect the bolts and enjoy the plane.

Gary
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  #27  
Old 11-24-2010, 09:49 AM
MartySantic's Avatar
MartySantic MartySantic is offline
 
Join Date: Apr 2008
Location: Davenport, IA
Posts: 1,369
Default

Quote:
Originally Posted by jersey View Post
This is a serious problem!!!!!

Found upper left and lower left bolts finger tight. I removed all bolts and reinstalled with locktite blue. Cut a section of the cowl out to access the upper left. Reinstalled the cut out with nut plates and aluminum tabs for future inspections. I don't fully trust it yet. If anybody is interested, I will be glad to send photos via email.

Gary
Gary asked me to post his photo's as he did not know how to do it. So, here are the photos of Gary's modification to the top shroud. A very eloquent change that allows access to the top left capscrew.











__________________
Marty Santic ----- W9EAA
RV-12 N128MS ----- Now Flying
My RV-12 Build Log - http://www.martysrv12.blogspot.com/
Davenport, IA

Last edited by MartySantic : 11-29-2010 at 12:08 PM.
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  #28  
Old 11-24-2010, 10:06 AM
MartySantic's Avatar
MartySantic MartySantic is offline
 
Join Date: Apr 2008
Location: Davenport, IA
Posts: 1,369
Default

Quote:
Originally Posted by jersey View Post
John I think your right about the lock washers not performing. I noticed that the engine mounting bracket arm was flexing slightly when I was aligning the bolts. Although they firmed up when I tightened the bolts to the engine it would seem that they shouldn't rely solely on the engine case for rigidity. This is a high speed, high compression engine. It seems to me that a significant amount of energy retention would be concentrating where the brackets clamp to the engine. I'm probably over-analyzing. Hopefully Vans engineers will get back to us soon. In the meantime I will continue to inspect the bolts and enjoy the plane.

Gary
The following links and for that matter, the entire website is very interesting. The information and data clearly demonstrates how ineffective split lockwashers are and in some cases the bolt/joint is better WITHOUT the lockwasher. (Look at the graph).

http://www.boltscience.com/pages/vibloose.htm

http://www.boltscience.com/pages/hel...ingwashers.htm

AND the video.....

http://www.boltscience.com/pages/jun...ringwasher.htm

I sent all of this to Van's, last week.
__________________
Marty Santic ----- W9EAA
RV-12 N128MS ----- Now Flying
My RV-12 Build Log - http://www.martysrv12.blogspot.com/
Davenport, IA
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  #29  
Old 11-24-2010, 10:15 AM
MartySantic's Avatar
MartySantic MartySantic is offline
 
Join Date: Apr 2008
Location: Davenport, IA
Posts: 1,369
Default

Quote:
Originally Posted by LIMA HOTEL View Post
I think the best solution for this problem would be to use the same kind of lock washers under the engine mount cap screws as we use under the prop attach bolts. Lets see what Van's comes up with.
Larry
A very interesting article on bolt locking devices other than the split lockwasher. The NordLock washer is a VERY interesting device once understood. (No wonder Sensenich uses it!)

http://contrails.free.fr/article_bol...ng_devices.php

This was also sent to Van's last week.
__________________
Marty Santic ----- W9EAA
RV-12 N128MS ----- Now Flying
My RV-12 Build Log - http://www.martysrv12.blogspot.com/
Davenport, IA

Last edited by MartySantic : 11-24-2010 at 10:21 AM.
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  #30  
Old 11-24-2010, 10:17 AM
JBPILOT JBPILOT is offline
 
Join Date: Nov 2007
Location: Jesup, Iowa
Posts: 1,545
Default Hey Gary - -

EXCELLENT Patch ! Good job ! I really like it ! I did not take as much time. If I ever have to go back in, that will be my choice.

John Bender
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