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Want to buy an RV-6, but I have a question on missing roll bar support

R

[email protected]

I'm New Here
I am looking to purchase a 2000 Vans RV6A. however the stainless steel support rod from the dash to the rollover bar is missing and no sign of a hole through the dash cover,would this be dificult to retrofit.
Cheers Rob
 
Contortion

Welcome to VAF, Rob.

Other than having to crawl under the dash, the rivetting may pose problems but they could probably be substituted with AN3 bolts and nuts. Do you know whether the slot for the forward end has been cut in the dash?

Best,
 
pierre smith said:
Welcome to VAF, Rob.

Other than having to crawl under the dash, the rivetting may pose problems but they could probably be substituted with AN3 bolts and nuts. Do you know whether the slot for the forward end has been cut in the dash?

Best,
Click to expand...

There is a section of 3/4" X 3/4" angle riveted to the center rib under the forward skin (between the panel and cowl). There is also a doubler plate riveted where the roll-bar support attaches to the rib and angle. If all of that is missing it would be difficult (not impossible) to install in an assembled aircraft. Hopefully only the center support is missing and all the mounting structure is in place.
 
AlexPeterson said:
Wow, without that part, you don't have a roll bar. What else important is missing from the a/c?
Click to expand...

Check for the screws holding the fuselage belly skin to the wings. :)

Seriously though, look for the structure under the dash that would let you retrofit the support. If it's not there, it's not the end of the world. Keep in mind that tip-up canopies fly without *any* structure forward of the pilot on the canopy. Yes, the forward rollover bar will be compromised without that support, but the amount of protection it offers won't go completely to zero.

You might check whether the main roll bar is the standard size, or if it was beefed up at all to compensate for the lost forward support.
 
rocketbob said:
Neither does the 8, FWIW... no question its stronger but is it really necessary?
Click to expand...

The RV8(A) is a tandem aircraft and the rollover bar has a considerably smaller span. In respect of the brace on the RV6(A) this is verbatim what Vans has to say on this issue:

"This centre brace is a structural piece that should be installed otherwise the roll bar will most certainly collapse if ever needed".

That's the definitive answer from the designer of the aircraft.

From the examples I've seen of side-by-side slider tipovers it seems to me that the roll bar is struggling even with the brace installed. Generally there is substantial deformation of the roll bar.

For those interested I recommend you go here to the Anti-Splat site and scroll across to the Nose Job Installation Video. In the first 30 seconds of the video you will see several examples of tipped over RVs and you can see for yourself what effect it had on the braced rollover bar.

http://antisplataero.com/Videos.html

As they say, a picture is worth a thousand words.
 
Captain Avgas said:
From the examples I've seen of side-by-side slider tipovers it seems to me that the roll bar is struggling even with the brace installed. Generally there is substantial deformation of the roll bar.
Click to expand...

Having been up close and personal with a nosegear failure and the scars to prove it from digging a friend out, the slider frame likely does as much for preventing the rollbar from tipping and I believe the structure would do fine without the brace. Just my $.02 based on experience but I wouldn't build one that way.
 
Snowflake said:
Keep in mind that tip-up canopies fly without *any* structure forward of the pilot on the canopy.
Click to expand...


This statement needs to be clarified for the benefit of folks still doing their initial RV research.

True, the tipup RV-6/A has no forward roll bar, but it does have a substantial roll bar structure immediately behind the occupants heads which the slider canopy doesn't have. The tipup roll bar is actually closer to the occupant's heads than the roll bar in the slider.

Consequently, the above quote is not a valid comparison of the roll over structures of the two models.
 
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Photos?

[email protected] said:
I am looking to purchase a 2000 Vans RV6A. however the stainless steel support rod from the dash to the rollover bar is missing and no sign of a hole through the dash cover,would this be dificult to retrofit.
Cheers Rob
Click to expand...

Do you have any photos of this suspect condition? I must admit that when I first read your post, I thought you were pulling our chain. A photo or two would certainly lend credence to this discussion.
 
Snowflake said:
Check for the screws holding the fuselage belly skin to the wings. :)

Seriously though, look for the structure under the dash that would let you retrofit the support. If it's not there, it's not the end of the world. Keep in mind that tip-up canopies fly without *any* structure forward of the pilot on the canopy. Yes, the forward rollover bar will be compromised without that support, but the amount of protection it offers won't go completely to zero.
You might check whether the main roll bar is the standard size, or if it was beefed up at all to compensate for the lost forward support.
Click to expand...

Rob,
With all due respect, statements like this, from someone that is not fully familiar with all the design aspects of the RV-6 are very dangerous, and in my opinion, one of the few negative aspects of the VAF forums.

The brace for the roll bar (and all of its related structure) should be considered a very integral part of the roll bar. I know of one fatal accident where the roll bar folded fwd while an RV-6 slid upside down and the pilot was killed. I don't know any specifics... whether it was found that the brace had not been installed, etc. Doesn't matter, any compromise of the roll bar system should not be taken lightly.
Regardless... my point is that with your above statement (particularly the highlighted portion) you could be adding confidence to the O.P. regarding not to be worried about it.

When purchasing an RV built by someone else it needs to be looked over very carefully. If I were inspecting one and found a major deviation such as described here, I would wonder what other casual engineering decisions were made and probably look doubly careful at the rest of the airplane.
 
So, from a non 6 guy, the following is purely guesstimation.

If the slider uses the braced front roll bar, and the tipper uses a rear roll bar, and the subject airplane has the front roll bar, but not the brace or the hole in the forward skin to accommodate said brace, is is possible that the aircraft was originally a tipper, that got converted to a slider??

If so, is it possible that the rear roll bar is still in place??

Photos of the entire canopy/cockpit would probably help here.
 
Mike S said:
So, from a non 6 guy, the following is purely guesstimation.

If the slider uses the braced front roll bar, and the tipper uses a rear roll bar, and the subject airplane has the front roll bar, but not the brace or the hole in the forward skin to accommodate said brace, is is possible that the aircraft was originally a tipper, that got converted to a slider??

If so, is it possible that the rear roll bar is still in place??

Photos of the entire canopy/cockpit would probably help here.
Click to expand...

After building a 7 I would say this is not possible, The forward structures on a tip up and a slider are completely different in the way they are constructed. Also if the rear brace was still present there would be no way to slide the canopy back.

Does anyone have any photos of the very first 6's built? Does it have the brace in it? I have never seen it.

-david
 
I remember discussing this change with one of our customers 7 or 8 years ago (not sure it's the same aircraft). He explained that he omitted the brace for a cleaner appearance. I don't recall if he strengthened the rollbar in any way to compensate for this change.
 
Have the seller install the brace per plans as part of the sale? This assumes that the seller is the builder
 
I would agree that the roll-over structure is almost entirely compromised without that forward brace. There is very little that attaches the roll bar base to the structure. It is basically clamped to the longeron and could not withstand any significant fore/aft load without that support.
 
rv7boy said:
Do you have any photos of this suspect condition? I must admit that when I first read your post, I thought you were pulling our chain. A photo or two would certainly lend credence to this discussion.
Click to expand...

I am not the original poster but I have access to photos of the RV6A in question and I am posting them with the call sign removed.

You can access a larger, higher resolution photo by double left clicking on the images.



 
I would be curious to see if the weldment on top of the roll bar that the brace bolts to is there or if they cut it off.
I could not imagine trying to retrofit the brace into a finished aircraft. It would be a very difficult job. If the weldment is missing, it would require removal of the windscreen and roll bar to have it welded back in.

In my opinion, this airplane is a death trap. How did this even get an airworthiness cert. ?
 
pierre smith said:
Jon, airplanes aren't required to have rollbars. Cherokees and Sonex don't. It was Van's idea.

Best,
Click to expand...

Thanks Pierre. Just shows my lack of understanding of what deviations from the manufacturers design are evidently allowed and can still be signed off on.
Given the incidents of roll overs in the A models, I still feel this airplane is unsafe to fly. Frankly, regardless of where the little wheel is.....

PS - I have been on my back before in an off field landing of my '42 L3. I would have been dead in a low wing with no roll bar or support structure. It was a very low speed roll over in a clover field. I walked away.
 
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JonJay said:
Thanks Pierre. Just shows my lack of understanding of what deviations from the manufacturers design are evidently allowed and can still be signed off on.
Click to expand...

We're dealing with experimental aviation. While the RV in question has less rollover protection than one built to plans, it in no way violates any FARs or any requirements for obtaining an airworthiness certificate.

The builder is the manufacturer. We are free to modify, ignore or ruin any design as we wish. The RVs have blurred the lines between experimental and standard category for many folks, but they still are certified experimental just as your one-off, Briggs and Stratton powered tri-plane would be.
 
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