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 > Model Specific > RV-12/RV-12iS
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #11  
Old 11-17-2015, 08:36 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 3,103
Default

Bob,

As an engineer you know we make our bread and butter answering the questions about what should be done when the OEM specs aren't met. I would not disagree with your statements, but I do think you are being overly conservative in this application. Maybe it's just my experience as a home builder seeing other applications, but I would still be comfortable with his suggested substitution. There are only a few critical applications like landing gear, cylinder head retention and prop bolts that raise the hairs on the back of my neck. Even if one bolt did fail on the water pump (and why would it since preload is most of the stress) you'd just get a leak you could address. I think the probability and consequences in this application result in low risk.

Rich
Reply With Quote
  #12  
Old 11-17-2015, 10:33 PM
tjo tjo is offline
 
Join Date: Dec 2009
Location: La Center,wa
Posts: 242
Default

You guys are way over thinking this. The substitution is fine unless we are talking about cylinder bolts, or case bolts, or rod bolts, but if that were true, they wouldn't be grade 8.8, which is the SAE grade 5 equivalent.

It sounds like they used the low strength bolts to save the case and make it so the bolt would fail if over torqued. I think the only risk with a higher strength bolt is overtorquing and damaging the engine case (or whatever the bolt is threading into).

Tim

Last edited by tjo : 11-17-2015 at 10:37 PM.
Reply With Quote
  #13  
Old 11-18-2015, 02:58 AM
Captain Avgas Captain Avgas is offline
 
Join Date: Oct 2005
Location: Melbourne, Australia
Posts: 1,959
Default

Quote:
Originally Posted by RFSchaller View Post
Bob,

I would not disagree with your statements, but I do think you are being overly conservative in this application.
Rich
Rich, you are right, in this particular case I have been extremely conservative, maybe too conservative. But in my defence I have had one eye on the original question and the other eye on the VansAirforce general audience, the bulk of whom do not come from a scientific background. We owe it to them to stress that changing out structural fasteners with those in any way different from that specified by the design engineer is not an option to be taken lightly by the uninitiated. At least the original poster had the common sense to ask the question and he should receive credit for that.

I have been impressed with the technical calibre of posts made by all the contributors to this thread and I'm confident the OP can now make an informed decision.
__________________
You’re only as good as your last landing
Bob Barrow
RV7A
Reply With Quote
  #14  
Old 11-18-2015, 03:53 AM
dbhill916's Avatar
dbhill916 dbhill916 is offline
 
Join Date: May 2013
Location: Westerville, OH
Posts: 166
Thumbs up thank you

Quote:
Originally Posted by Captain Avgas View Post
...At least the original poster had the common sense to ask the question and he should receive credit for that.

I have been impressed with the technical calibre of posts made by all the contributors to this thread and I'm confident the OP can now make an informed decision.
Gentlemen all,

I thank you all for the wealth of information and opinion. Many decades ago I was an engineer, but I think that only makes it dangerous for me to rely on my own analyses; thus the reason I asked the question here. The responses were exactly the kind of engineering discussion that is so informative on what might be perceived as an apparently trivial topic (nothing is trivial in aviation engineering!).

Jesse gets the credit for the optimal solution : Lockwood's web site shows that not only are they in stock, but they're much cheaper than LEAF's (except for the shipping fees.) Hopefully, I will have the best of both worlds: original specifications and timely availability.

In the event that they aren't shipped any time soon, I will wait until I find the original spec 8.8's.

thanks again for a lively discussion,
-dbh
__________________
David B. Hill
N76012
RV-12 #0760
Dues paid through 6-2022
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 04:17 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.