VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-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 > Safety
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #11  
Old 01-02-2022, 04:09 PM
Larry DeCamp Larry DeCamp is offline
 
Join Date: Apr 2010
Location: Clinton, Indiana
Posts: 1,211
Default Good input, but I will stir the pot a little.

So, for safety, van specifies large washers where they can be applied to keep the outer race from coming off the inner ball.
Yet, the kit is supplied with components that do not support the washer option, and Ralph has never seen one fail.
So, is it possible they are both acceptable, but conform to DIFFERENT material or design specs ?
__________________
Larry DeCamp
RV-4 fastback in process w/ Superior roller 360/AFP/G3X/CPI/Catto3b
Clinton, IN

Last edited by Larry DeCamp : 01-03-2022 at 09:26 AM.
Reply With Quote
  #12  
Old 01-02-2022, 07:40 PM
RV7 To Go's Avatar
RV7 To Go RV7 To Go is offline
 
Join Date: May 2011
Location: Ontario, Canada
Posts: 333
Default

Quote:
Originally Posted by Toobuilder View Post

If you want to make it easier, just drill through the stud at the swage countersink and knock it free with a punch.
This is what I have done on two 4's and my 7. Very easy to do. Only takes a couple minutes to drill off the flare and drive out the stud. install with a bolt and large washer. Might need to enlarge the opening in the fuselage a bit to clear.

All of the RV's built on our field (over a dozen) have been done this way, ever since an MD-RA inspector pointed it out as potential issue years ago. Even though we have never heard of a failure of one of these ball ends we still do it just to be safe.
__________________
Al
___________
RV4 - Bought 2013 Sold 2017 after 450 hrs
RV7 - Built in 6.5 yrs & Flying 2017
RV4 - Built 2021 Time flown and Sold
RV8 - Building 2022
Reply With Quote
  #13  
Old 01-02-2022, 07:53 PM
Stewbronco Stewbronco is offline
 
Join Date: Sep 2019
Location: Langley BC
Posts: 264
Default Or just get the correct heim joint

Very simple instead of modifying the ballpoint stud to just order the same one used on top of flap rod from VANS. On advise from a very well respected MDRA inspector that had made a " containment "arm out of aluminum I addressed this issue without molesting the heim joint . Vans designed the GREAT plane but this would be better in double shear and the rod end would need to be contained on a racecar. I don't know how to post pictures ...but Larry ..I sent you a PM

Last edited by Stewbronco : 01-02-2022 at 08:24 PM.
Reply With Quote
  #14  
Old 01-03-2022, 08:27 AM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
Posts: 4,897
Default

Fair point to order a std. heim joint in a new build, but for those with the "studded" version on hand, it takes less time to press out the stud than to open the Van's website on your computer.
__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
______________
Harmon Rocket II -SDS EFI
1940 Taylorcraft BL-65
1984 L39C - SOLD
RV-8 - SDS CPI - SOLD
Reply With Quote
  #15  
Old 01-03-2022, 04:26 PM
Scott Hersha Scott Hersha is offline
 
Join Date: Jan 2005
Location: Cincinnati, OH
Posts: 2,197
Default

Good points made, and easy to accomplish for me on my ďnewĒ RV6 build since Iím at that point - and I have the correct replacement bearings that just require me to grind a bigger hole in my fuse for the extra bolt end/washer assembly. But Iím still curious about the company still recommending the screw mount bearing that they do. Is there any record of failure of this joint? It seems like, with more than 11,000 units flying with this configuration, there should be some data on failures if itís a problem. Does anyone know if Vans has an opinion on this?

Iím not trying to second guess anyone, but trying to not fix something that isnít broken and possibly never has broken. Iím not an aeronautical or structures engineer, but the folks that designed my airplane are. Why are they still recommending this bearing?
__________________
SH
RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
RV4/bought 2016/sold/2017
RV8/2018 built/Sold(sadly)
RV4/bought 2019/sold2021
RV6/Used kit purchased 2021 building
Cincinnati, OH/KHAO
JAN2022
Reply With Quote
  #16  
Old 01-03-2022, 04:40 PM
Ralph Inkster Ralph Inkster is offline
 
Join Date: Feb 2008
Location: Calgary, Alberta
Posts: 1,753
Default

[quote=Scott Hersha;1579
Does anyone know if Vans has an opinion on this?

I’m not trying to second guess anyone, but trying to not fix something that isn’t broken and possibly never has broken. I’m not an aeronautical or structures engineer, but the folks that designed my airplane are. Why are they still recommending this bearing?[/QUOTE]


Well, its the holiday season, excess food & too much idle time = lets 'Overthink the engineers' on something else & create another preceived issue.
__________________
Ralph
built a few RVs, rebuilt a few more, hot rodded more, & maintained/updated a big bunch more

Last edited by Ralph Inkster : 01-03-2022 at 04:48 PM.
Reply With Quote
  #17  
Old 01-03-2022, 05:30 PM
Champ's Avatar
Champ Champ is offline
 
Join Date: Apr 2012
Location: Kingsville, Ontario, Canada
Posts: 390
Default

Started with a std rod end, bolt & big washer then switched to Vanís design. On final inspection my MDRA rejected the Vanís design and would only approve a bolt/big washer attachment.
__________________
Dennis Enns
Bellanca Champ 7ACA since 1986, restored 1990.
RV-8 IO375, MTV-9-B/183-50a, PMags, OW Award Oshkosh 2017
2022 Donation In
Reply With Quote
  #18  
Old 01-03-2022, 06:57 PM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
Posts: 4,897
Default

Quote:
Originally Posted by Ralph Inkster View Post

Well, its the holiday season, excess food & too much idle time = lets 'Overthink the engineers' on something else & create another preceived issue.
Well, that's a bit harsh Ralph. The Op's question is valid: If the big washer is standard practice on all rod ends to contain the race within the body, and this "studded" unit is metallurgically identical to the other Heim joints that DO require the washer, why is it OK to ignore this containment practice?

And I agree - I have never seen a failed/uncontained race. I simply removed the stud in my Rocket because I changed the flap geometry and the stud would not work.
__________________
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
______________
Harmon Rocket II -SDS EFI
1940 Taylorcraft BL-65
1984 L39C - SOLD
RV-8 - SDS CPI - SOLD
Reply With Quote
  #19  
Old 01-09-2022, 01:12 PM
wawrzynskivp wawrzynskivp is offline
 
Join Date: Feb 2018
Location: Incline Village Nv
Posts: 308
Default To washer or not to washer

I recall paying a very experienced test pilot to go over my build prior to first flight. I learned a lot from that, but the one thing that seemed out of place was the discussion of the push rod to flap attachment on my RV7.

Unless I missed something, Van's Plans do not call out a washer on that particular Heim Joint. I assume this is due to the reliability of the joint, the need to cut the fuselage for clearance, and the problem generated by a washer hanging up on the aircraft skin.

The inspector shared his desire to see a washer there as personal and not based on any specific knowledge of failures. I can certainly see his point.

However, in that particular assembly I would point to the aluminum tube/pushrod being scored along its inner circumference during threading as being the most likely impeding failure over time. I wouldn't call it likely, or even remotely likely, just much more likely to see fatigue failure in scored aluminum rather than smooth steel.

The inspector's observation bothered me as the consequence of failure weighs heavily on peace of mind, even though the likelihood is so remote at least in my mind to be undefined. How many things can we imagine as going wrong?

I guess I am asking this question again: Does anyone know of a failure mode for these joints other than obvious overload?
Reply With Quote
  #20  
Old 01-09-2022, 01:36 PM
bjdecker's Avatar
bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 1,134
Default

Quote:
Originally Posted by wawrzynskivp View Post
How many things can we imagine as going wrong?
That's a very long list my friend. For what it's worth, the failure of that particular CM-4MS rod end bearing isn't on mine

That particular rod end is loaded in predominately in shear, a failure is likely going to happen when extending the flaps (higher loading). Back of the envelope FMEA tells me that the push rod will bend & bind before the attachment fails -- likely causing the flap motor to stop turning, blowing a fuse/circuit breaker and causing a partial or split/partial flap configuration.

...but that's just me...
__________________
Brian Decker
RV-7 (Flying)
Reply With Quote
Reply


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 04:52 AM.


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.