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-   -   Poor Riveting (https://vansairforce.net/community/showthread.php?t=146684)

cccjbr6 02-19-2017 07:10 AM

Thanks for posting Vic. Your posts about bad build quality, bad maintenance, and other problems you encounter are especially valuable to non-builders like me. Could these posts be assembled in dedicated "stickies" by subject (or even better in their own forum in the education section) so they would be easy to find and study?

vic syracuse 02-19-2017 07:31 AM

Thanks for the comments, Chris. That's a good idea. I need to motivate myself to contribute once a week or so with some of my findings so we all can learn.

Vic

vic syracuse 02-19-2017 08:04 AM

Vertical fin attach
 
Here's another one on an RV-7 found this past week. It had been flying for 7 years, and allegedly maintained by an A&P. Personally, I think the riveting shown should have been caught on the initial airworthiness inspection, if not the 6-7 subsequent inspections. I think 2 out of the 7 rivets are acceptable. :(

Just remember that there is a simple formual for determining a set rivet:

It should be approximately 1/2 the original diameter in height and approximately 1.5 original diameters in width. Diameters here are referring to the unset rivet measurements. As an example, a 1/8" rivet as seen here (AN470) should measure 3/16" across and 1/16" high after being set. After a while you will be able to eyeball it.



acam37 02-19-2017 09:56 AM

Looks like those could be hit again and they would be perfect

KatanaPilot 02-19-2017 10:29 AM

Quote:

Originally Posted by acam37 (Post 1151337)
Looks like those could be hit again and they would be perfect

I'm really new at aircraft sheet metal work, but if workmanship like this that is fairly accessible and visible has been considered acceptable - both for the initial airworthiness sign-off and subsequent condition inspections - what about all of the inaccessible (and long hidden) fasteners in the wings and other critical areas?

All I can surmise from seeing these and other examples of marginal construction is that Van and his engineers did a heck of job designing to the lowest common denominator. Otherwise, these airplanes would be falling out of the sky.

For me, it confirms the advantage of having several sets of trained and experienced eyes (in my case at Synergy) look at each and every component I build.

RV7ForMe 02-19-2017 11:52 AM

Where do you find these planes?
 
Geez! I mean those do not look good to anyone. Not even to an amateur like me. How the heck do these birds get signed off? Kudos to Vans for over-engineering the heck out of these planes. Thanks for posting these...

rv8ch 02-19-2017 01:32 PM

2 of 7 or 2 of 9?
 
Quote:

Originally Posted by vic syracuse (Post 1151298)
... I think 2 out of the 7 rivets are acceptable. :(


Vic, I agree completely that these photos are very helpful.

One point - I assume you mean 2 of the 9 rivets there are ok? Can I guess you mean the one on the far left and the one at the lowest point on the photo? They seem to be slightly overdriven IMHO, but I agree that they look "ok", from the angle I can make out in the photo. Perhaps the bottom right corner rivet might be "ok", if slightly underdriven. If a picture is worth a 1000 words, seeing it in 3d with two live eyes is worth 1000 pictures. :)

vic syracuse 02-19-2017 02:18 PM

Yes, my bad. I guess I can't count. :)
The two you mentioned are set properly. The others could be fixed in about 2 minutes with a gun and bucking bar. They are easily accessible.

There have been a few comments about the Vans aircraft being over engineered. No doubt. I remember taking my first piece on the rv-4 to the FAA when we had to to get preclosure signoffs. He asked if I was building a tank. I didn't know any better until I looked at the inside of a Cessna tail. Yikes! I didn't understand how it stayed on, but I certainly understood why they were cracking from everyone pushing down on the tails to move them around!

That being said (that they are overengineered) they should still be built right. Anything worth doing is worth doing right. These pictures I am showing you are not becasue I am picky. Quite candidly, none of these would have been given an airworthiness certificate if I was the DAR. A lot of them are fixable---some even during the course of the inspection like the RV-7 vertical fin. Others, like the RV-10, are going to take a major rebuild.

As someone also mentioned, it makes you wonder about the rest of the aircraft. I am working on posting some pictures in a bit that will drive that point home with a big hammer. :(

Vic

vic syracuse 02-19-2017 02:29 PM

What else is lurking
 
So, in the spirit of what else might be lurking behind visible poor workmanship, take a look at the following:

Missing rivets on the horizontal stabilizer. Should have been caught on airworthiness inspection.



Pop rivets on the engine mount attachments. Really?



How's this for wallowed out holes on the landing gear attachment?



This is the horizontal stabilizer attachment, the first clue that one might want to look deeper.



Real friends don't let their friends buy RV's without a thorugh prebuy.

Vic

RV74ME 02-19-2017 08:05 PM

On the subject of acceptable rivets, I'm wondering is it ok if you have a properly formed shop head that is "overdriven" (won't fit in the rivet gauge), but still meets the minimum head height? Hope that makes sense.

rv9builder 02-19-2017 08:20 PM

Quote:

Originally Posted by RV74ME (Post 1151506)
On the subject of acceptable rivets, I'm wondering is it ok if you have a properly formed shop head that is "overdriven" (won't fit in the rivet gauge), but still meets the minimum head height? Hope that makes sense.

As long as it meets the minimum head height, it's OK if the diameter is too large to fit in the rivet gauge. (That's assuming it isn't so large in diameter that the head is starting to crack.)

RV7A Flyer 02-19-2017 10:31 PM

Quote:

Originally Posted by rv9builder (Post 1151509)
As long as it meets the minimum head height, it's OK if the diameter is too large to fit in the rivet gauge. (That's assuming it isn't so large in diameter that the head is starting to crack.)

In fact, it's not *supposed* to fit in the rivet gauge. It's a go-nogo gauge...if the rivet head can fit inside the hole, it's *not* driven enough.

ETA: Yes, I know that the hole is supposed to be *EXACTLY* the ideal (minimum) diameter, and an absolutely perfectly set rivet will "pop" into the hole with no slop at all...but really...how many times does that actually happen? Better to be slightly overdriven, and the gauge will usually just kind of "wobble" on the head, but the head won't go all the way through, than to have one that is underdriven and doesn't "fill the hole".

az_gila 02-20-2017 01:29 AM

Look the same, but -
 
Quote:

Originally Posted by RV7A Flyer (Post 1151524)
In fact, it's not *supposed* to fit in the rivet gauge. It's a go-nogo gauge...if the rivet head can fit inside the hole, it's *not* driven enough.

ETA: Yes, I know that the hole is supposed to be *EXACTLY* the ideal (minimum) diameter, and an absolutely perfectly set rivet will "pop" into the hole with no slop at all...but really...how many times does that actually happen? Better to be slightly overdriven, and the gauge will usually just kind of "wobble" on the head, but the head won't go all the way through, than to have one that is underdriven and doesn't "fill the hole".

Check your gauges first.

This one from Spruce is a No-Go one as mentioned above -

https://www.aircraftspruce.com/pages...rivetgauge.php

But some of the older ones, or ones from other sources, look identical but are set up to measure an exact 1.5D/0.5D rivet head.

Make sure you know which version you are using...:confused:

vic syracuse 02-20-2017 05:30 AM

Overdriven rivets actually have more tensile strength but you need to be careful around thin materials. They can be cause of cracks developing in the material, and if you look closely you can sometimes see the two materials begin to separate.

That being said, I would rather see a few overdriven rivets in a project than underdriven ones, as long as they all aren't concentrated on 1 piece.

There may be a perfect airplane out there, but I haven't seen it yet, including mine. Everyone once in a while there is a rivet that is just a bugger to get to, and it comes out less than perfect. You can have up to 10% of your rivets being bad and it still be acceptable, again as long as they aren't concentrated on one piece.

So, for the newbies, don't fret too much. Ask for help if you are unsure. The pictures that have been shown here are the worst of the worst. They didn't need a gauge to tell the builder they weren't right.

Vic

Oliver 02-23-2017 01:51 PM

Quote:

Originally Posted by RV7A Flyer (Post 1151524)
In fact, it's not *supposed* to fit in the rivet gauge. It's a go-nogo gauge...if the rivet head can fit inside the hole, it's *not* driven enough. [...]

We have two gauges, from ATS and from Cleaveland. Both are set for 1.5 x rivet diameter. Many of the 3/32? rivets will however end up not high enough, if driven to a width of 1.5x.

1.3x rivet diameter is technically sufficient. I therefore made a 1.3x no-go gauge, to measure the absolute minimum diameter. With shorter rivets, I usually end up at a width of around 1.4x, what still leaves an acceptable height.

I also feel that a width of 1.3x - 1.4x can be achieved with only a short burst. A width of over 1.5x, so that the rivet doesn?t pass the gauge anymore, however requires quite a bit more hammering with the rivet gun, what increases the risk to slip with either the gun or the bucking bar.

I drive longer rivets to a diameter of 1.5x, though.

Oliver

David Paule 02-23-2017 02:24 PM

I follow the riveting spec on Van's site. The acceptable dimensions it lists are not exactly the rule of thumb, worth noting, and the commercial rivet gauges I've seen do not meet the spec.

I made a -3 gauge and a -4 gauge for myself.

Dave

rvbuilder2002 02-23-2017 03:04 PM

Quote:

Originally Posted by Oliver (Post 1152627)
We have two gauges, from ATS and from Cleaveland. Both are set for 1.5 x rivet diameter. Many of the 3/32” rivets will however end up not high enough, if driven to a width of 1.5x.

1.3x rivet diameter is technically sufficient. I therefore made a 1.3x no-go gauge, to measure the absolute minimum diameter. With shorter rivets, I usually end up at a width of around 1.4x, what still leaves an acceptable height.

I also feel that a width of 1.3x - 1.4x can be achieved with only a short burst. A width of over 1.5x, so that the rivet doesn’t pass the gauge anymore, however requires quite a bit more hammering with the rivet gun, what increases the risk to slip with either the gun or the bucking bar.

I drive longer rivets to a diameter of 1.5x, though.

Oliver

To ex[and a bit more on the info in your post.....

The 1.5 rule of thumb (and all of the rivet gauges that have been made using it), is not a specification. It is a genral us guide line / rule of thumb that is much easier to follow that the actual specification.
The specification allows quite a bit of latitude/tolerance one side or the other of teh 1.5X guide line, for shop head diam. and height.

LettersFromFlyoverCountry 02-26-2017 08:36 AM

I've been doing a LOT of riveting -- the aft bulkhead on the RV-12 for example -- and it came out great.

You know why?

Because just as I start to squeeze the rivet, I say to myself, "Stay out of Vic's threads. Stay out of Vic's threads. Stay out of Vic's threads."


az_gila 02-26-2017 08:50 AM

Quote:

Originally Posted by rvbuilder2002 (Post 1152647)
To ex[and a bit more on the info in your post.....

The 1.5 rule of thumb (and all of the rivet gauges that have been made using it), is not a specification. It is a genral us guide line / rule of thumb that is much easier to follow that the actual specification.
The specification allows quite a bit of latitude/tolerance one side or the other of teh 1.5X guide line, for shop head diam. and height.

This is the original - html spec version created in 1997 by Brian Yablon and myself - page that lists the spec Vans 'borrowed' that Scott mentions.

http://web.archive.org/web/200008161...ash.net/~gila/

Note the picture on the main page, many builders use the height portion of the rivet gauge incorrectly when measuring the shop height on dimpled material.

vic syracuse 02-26-2017 09:23 AM

Quote:

Originally Posted by LettersFromFlyoverCountry (Post 1153341)
I've been doing a LOT of riveting -- the aft bulkhead on the RV-12 for example -- and it came out great.

You know why?

Because just as I start to squeeze the rivet, I say to myself, "Stay out of Vic's threads. Stay out of Vic's threads. Stay out of Vic's threads."


Too funny. But glad I am helping to make a difference. :)

Vic

rdamazio 02-27-2017 03:16 PM

Whatever lack of self-esteem I had about my rivets is now gone after seeing this :p mine look perfect in comparison...

Palamedes 03-01-2017 06:38 PM

Quote:

Originally Posted by rdamazio (Post 1153695)
Whatever lack of self-esteem I had about my rivets is now gone after seeing this :p mine look perfect in comparison...

Exactly. I'm very confident in my rivets now!

ChiefPilot 03-01-2017 06:55 PM

Quote:

Originally Posted by vic syracuse (Post 1151424)
Missing rivets on the horizontal stabilizer. Should have been caught on airworthiness inspection.


That's actually kind of nice. Makes complying with the service bulletin much easier.


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