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Old 12-16-2014, 04:36 PM
Tom Martin Tom Martin is offline
 
Join Date: Jan 2005
Location: Ontario, Canada
Posts: 1,544
Default bearing maintenance

There are two bearings that hold the main front sticks in the RV14 and the following picture shows one of them.



This is a well designed item that captures a COM3-5 bearing between the two pieces of metal, much the same way as the aileron hinge brackets.
There are 8 -3 rivets that hold the bearing in place and another 8 -4 rivets that hold the bracket to the small bulkhead that is forward of the main spar. There are two dash 8 screws that also go through the bulkhead and tie into a stiffener on the other side.
Although I have yet to install any controls I am sure that this item incorporates the "stops" for stick travel in the upper and lower bumps.

This is a well thought out, light and strong unit.
The problem comes with long term maintenance. This is going to one very difficult bearing to replace, 16 rivets to drill out in a pretty tight space. I know that these bearings are very reliable put eventually it will have to be changed out, 10 or even thirty years down the road.
I am all for building light, but in this case I believe it would be prudent for the engineers to take a second look at this bracket and add some extra screws, or bolts so that the unit can be removed without drilling and riveting. It would turn a two day job into a couple of easy hours.

This is not a big deal, build on, but take a look at it yourself and imagine the repair, it will not be pretty.
I have been building and maintaining RVs and rockets for over 20 years and stuff does wear out. You will be a surprised when your brand new airplane turns 10 years old!
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EVO F1 Rocket 1000 hours,
2010 SARL Rocket 100 race, average speed of 238.6 knots/274.6mph
RV4, RV7, RV10, two HRIIs and five F1 Rockets
RV14 Tail dragger

Fairlea Field
St.Thomas, Ontario Canada, CYQS
fairleafield@gmail.com

Last edited by Tom Martin : 12-16-2014 at 07:05 PM.
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  #2  
Old 12-16-2014, 05:08 PM
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rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
Default

I don't mean to imply I think they will last forever, but the same bearing, in the same type of application is still going strong in the Blue RV-6A prototype at 26 years old with no sign of trouble.
They are in a well protected area, and if lubed (as they should be) once a year, it seems they will last a very long time.

BTW, I caution anyone making a change to this bracket without doing some detailed engineering.... As you mentioned, it is a control stop for the stick travel in the pitch control circuit. With the length of the stick, factored against the design load required to meet FAR 23 The loads they know an average pilot can easily exert), the loads this bracket / rib needs to be able to take are quite high. Hence, the reason there is more than just a couple screws used to mount it.
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Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")

Last edited by rvbuilder2002 : 12-16-2014 at 05:16 PM.
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  #3  
Old 12-16-2014, 05:16 PM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,218
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Quote:
Originally Posted by rvbuilder2002 View Post
I don't mean to imply I think they will last forever, but the same bearing, in the same type of application is still going strong in the Blue RV-6A prototype at 26 years old with no sign of trouble.
They are in a well protected area, and if lubed (as they should be) once a year, it seems they will last a very long time.
Scott, what is your lubricant of choice in these bearing?

Thanks,
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Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10
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  #4  
Old 12-16-2014, 05:18 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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Quote:
Originally Posted by Kyle Boatright View Post
Scott, what is your lubricant of choice in these bearing?

Thanks,
In our shop we use LPS-2
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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