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SB 14/12/06. (RV-12, F-1206F Bearing Bracket Cracks)

I don't have the kit yet so this may be a dumb question. It appears from the kit instruction diagrams that the vertical face of the two bearing bracket angles won't lay flat against the sloping face of the F1206 ribs unless forced into position. The only way I can see how that could happen would be if the brace/angle connection was forced to bend along the rivet line - which doesn't seem like a good idea. Is this what happens, or are the bearing angles pre-bent to conform to the slope of the ribs so that there is no need to distort the brace/angle connection to get it to fit?
Apologies in advance if I've misunderstood how it works.
 
SB

i just got the kit this week and it was $10.00. i called the company and they sent it right out

Donnie Mac
 
brace replacement

"I guarantee that it can be done, or the install document (which was confirmed while a test installation was done on the RV-12 prototype) would have been written differently.
As mentioned previously, the space is a little wider at the bottom, and the two ribs are slightly flexible at the back"

It would have been helpfull if the above statement would have been included in the instructions. I two removed the two top rivets to get the new part in place
 
so i removed my bracket today. besides a little blood , no problems. i have been holding off because my angle drill with 7/16'' clearance wont let me get a square shot at the forward rivets.well...........if you put a #30 drill in that spare chuck lying on your bench you can twist the chuck and drill it by hand. the side of the chuck slips into a lightening hole and you are 90 deg.! a box end wrench over the spindle of the chuck provides the pressure while you turn it by hand.5 minutes of aching hand and you are done.
 
Installed the kit yesterday. Took about 2 hours to drill out the old one and put in the new one. Used a #30 bit in my right angle die grinder and it worked well enough. It's the right time to make the change since I was working on section 24 and had easy access.
 
Crack

On my sixth conditional...over 600 hours...discovered a crack on the right aft rivet exactly the same as the one pictured in the service bulletin. Since it is in exactly the same location as the company airframe, it does provide more evidence to the theory that the crack is age related.

This possibility provides even more encouragement to the consideration of a pre-emptive fix. John Bender has a few more hours than I do and while he has no cracks, he sees the evidence as when, not if - enough so that he has already ordered the fix. Hopefully, more will see it as so. A brace that fails in flight could be tricky to handle...if possible at all.

Perhaps the saddest consequence of my find was that this was to be the first year in six that I was not expecting to remove the fuel tank....the poor thing deserves a break.

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I wonder if any of the aircraft with cracks have had their flaps deployed above 81 KIAS. Could that be a contributor?
 
For the most part, cracks in airframe parts are the result of cycle loading (lots of flexing cycles) not overload.
The first discovery was on the factory prototype at a flight Time of about 1000 hrs. All of the pilots that fly it do not exceed Vfe.
 
Shouldn't the rivets be installed the other way. Using the method that (when you can) the factory head always goes on side with the thinnest metal that you are assembling. I have mine installed the other way and no signs of cracks at 630 hours. Might make a difference??We will see as I will continue to inspect.


Brad Stiefvater
 
Shouldn't the rivets be installed the other way. Using the method that (when you can) the factory head always goes on side with the thinnest metal that you are assembling. I have mine installed the other way and no signs of cracks at 630 hours. Might make a difference??We will see as I will continue to inspect.
Good catch Brad...maybe so huh? The new set-up replaces the "ears" that attach to the vibrating bearing assembly with .064 aluminum instead of the original .040
That too should help with the flexing for sure.
 
I was finishing my 4th condition inspection yesterday. First year not to remove the tank. NOT. Contorted myself so I could check for the cracks. Yikes! Cracked both sides, and a third crack starting just for a bonus! Got my young and very flexible friend Sam to crawl into the baggage compartment (after removing the tank of course). A couple hours later we had extracted the offending bracket. A 12" #30 drill worked well for the forward facing rivets, after dismounting the AP servo and setting it aside. Used an air-powered right angle drill for the 3 rivets each side. Pictures below. Parts on order. Ten bucks well spent.

Airframe 120176, 4 years old, 227 hours. Well, maybe no tank out next year. LOL.

Sent photos to Van's. Very glad they found this problem. Obviously they go over the red demo airframe with an eagle eye. Glad they issued the SB, because I probably wouldn't have caught this in my airplane due to the location.

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Well John after seeing your 3rd crack starting. My idea is out the window.I guess I get to take the gas tank out again too_OH BOY!!

I just ordered the fix from Vans



Brad Stiefvater
 
Well John after seeing your 3rd crack starting. My idea is out the window.I guess I get to take the gas tank out again too_OH BOY!!

I just ordered the fix from Vans

Brad Stiefvater

My CI is due in July. Will order the parts cause taking the tank out, AGAIN will make it easier to install ADS-B-Out ****!! Thought the split mod was a panacea! Thanks, Brad and John!!
 
Well John after seeing your 3rd crack starting. My idea is out the window.I guess I get to take the gas tank out again too_OH BOY!!

I just ordered the fix from Vans

Brad Stiefvater

My CI is due in July. Will order the parts cause taking the tank out, AGAIN will make it easier to install ADS-B-Out ****!! Thought the split mod was a panacea! Thanks, Brad and John!!

The ************'s are due to the forum nazis!
 
3 rd crack

My 3 rd crack was just like BigJohn's photos but a little bit longer and on the same side. My total airframe time was similar. Would encourage everyone to take this SB seriously. Anyone that has 250 hrs or so on their airframe could have the problem. When I first reported my cracks I was the low guy on the airframe hours. Now we have a second airframe with similar hours and I would speculate that there are several others out there with the same problem.

Replacing water hoses, fuel hoses, carb sockets, carb rebuild and other 5 yr replacement items. Be safe.

Bob Kibby "N712BK
 
No cracks - 305 hours

Started an Annual Inspection and the bracket was the first thing I was anxious to see.
I examined very carefully and see no cracks. The rivets are not showing stress either.
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Flying since June 2010 and three hundred and five (305) hours on the plane.

Thanks Tony. There is some curiosity as to why hours doesn't appear to be a significant factor with the stress on this brace. In discussing with Brad, we both had a couple thoughts to throw out there. We both fly RV12 that are the same age with roughly 600 plus hours. I had a crack and Brad did not. One thought we discussed was how the wings are inserted. The brace is the flexing device for all of the forces applied to the flaperon torque tubes/arms. When the pilot guide and the actuation bracket are inserted into and onto the flaperon arm it is done so with a certain amount of force. A heavy hand, an an over aggressive push or even an "extra tight" fit would all seem to spell trouble for the brace. If it takes extraordinary strength to insert the wings, perhaps the brace will suffer.,

Second thought. This is a light plane with awful wing loading...that goes with the territory...its not an F-16. Many, many RV12 owners fly early morning donut runs or even sunset flights and intentionally avoid turbulent air. Others will max out the utility of the aircraft and fly long cross-country adventures which by noon will almost certainly involve tightening seat belts. Often, it becomes evident that the RV12 can handle more turbulence than the pilot finds comfortable. Uncomfortable on occasion yes, but very doable. The autopilot is a big assistance in those instances and saves lots of sudden, violent and tiring flaperon corrections. Certainly the company aircraft that discovered the crack has made its share of necessary cross-country flights. Again, the brace would seem to be the final resting place for the energy collected by all that stress.

All that said, the new brace is also a new design of brace. It is actually two separate pieces joined by some heavy solid rivets. The edges, now thicker sections connect directly to the flaperon bearing bracket and then to the thinner flexible brace itself.

Other than the recent skin to spar rivet wear SB, I don't know of any other bulletin where Van's requires (or recommends) an annual inspection of a potential SB problem. Interesting that they consider this bulletin to be of such value.
 
Other than the recent skin to spar rivet wear SB, I don't know of any other bulletin where Van's requires (or recommends) an annual inspection of a potential SB problem. Interesting that they consider this bulletin to be of such value.

The inspection interval is not because of a high concern of failure. It is actually just the opposite.
Because there is strong evidence that in most cases, evidence of cracks will not show up until a considerable amount of flight time has accumulated, regular inspection allows an owner to wait and install the updated part at their convenience, or when cracks are discovered.
A crack that is induced by repetitive load cycles (like this one) can be influenced by many factors (how well the part was deburred, etc.), so there will never be a specific number that it will show up. I would be surprised if many cracks are found prior to about 500 hrs.
 
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I got it to at 689hrs.:( I thought the replacement went as planned per the SB. New part installed, after getting to it maybe 2 hours labor at a leisure pace.;)No sweaty rivet on bottom of wing.:D
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My experience

Hi,

I was nervous about applying this mod, and was in two minds about the undertaking while I had the airplane in bits for the annual inspection - there was no signs of cracking, so no obvious requirement to do so at this time. Hamish offered to help and bashed out one mandrel thus committing me to complete the mod. Much of the work described below was undertaken by him, rather than myself as punishment ;-)

Having lost my 1/16 pin punch, we used a #52 drill bit as a punch to extract the rivet mandrels. It worked for the six rivets on the left and right sides of the assembly. Incidentally it also worked for the wing root mod which involved tapping out many more mandrels. I broke the drill bit, but the remaining length was long enough to complete all of these holes. Unsurprisingly the punch I had previously ordered arrived a day later!

Having drilled off the heads of the left/right rivets, we used a #30 drill bit as a punch to remove the remains of the rivets. The drill bit was short enough to get a reasonable swing with a hammer.

The problematic rivets are the four fore/aft ones. I considered attacking them from the rear (looking forward from inside the tailcone) with the 12 inch drill (I had the shop heads on the forward side of the assembly). I also considered cutting the bracket to bits with a dremel, to allow me to get at the four rivets with my 90 degree drill while remaining in cockpit area.

In the event Hamish used a strong pair of snips on the shop heads working from the cockpit area. These broke off the shop head and mandrel together. With some wiggling the bracket then broke free with the four fore/aft rivets still attached.

The replacement assembly, when correctly assembled by following the plans!!!, can be manoeuvred into place relatively easily and pulling the new rivets is the easiest part of the operation.

Having assembled the new parts incorrectly twice (in different wrong ways) I can confirm it is possible to wiggle the bracket into place even when incorrectly built ;-) My thanks to three fellow builders in the UK who offered me their kits to replace my botched up assembly job.

Now done, and I'm happy with the result.

Cheers...Keith
 
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My first condition inspection at 130 hours and the crack was there! Installed the new improved brace in about two hours (with tank and floor out already) and good to go. Can't figure out a way to attach a photo here as I use no social media, but have a few shots.
 
225 hrs in 1 year and no cracks for me,even admit to failing to retract flaps after takeoff. I was diligent in my deburring.
 
As Brad said, tape camera to a piece of fairly firm wire. Bend a 160 degree bend near the end so the camera is nearly looking back at you. Once inserted up thru rear-most inspection port and run up thru center section, you can twist as need to look as though you were in the rear looking forward toward the bracket in question. Takes a little time to bend wire and twist to get shots you want. Works. You can get this little camera into almost any part of the plane to see things. For $20 or so, handy to have around.

I finally picked up a cheap scope as you suggested. I wasted quite a bit of time poking around with the scope, until I finally figured out what you meant by going through the center section. After I figured out that I needed to place the scope through the hole that the control rods use, it was a piece of cake. Thanks John for this fantastic solution to a repetitive inspection. By the way, 240 hours and no cracks..................Tom
 
I finally picked up a cheap scope as you suggested. I wasted quite a bit of time poking around with the scope, until I finally figured out what you meant by going through the center section. After I figured out that I needed to place the scope through the hole that the control rods use, it was a piece of cake. Thanks John for this fantastic solution to a repetitive inspection. By the way, 240 hours and no cracks..................Tom

A bit of a thread drift sorry.
I have to agree on the usefulness of these things. I picked one of these up early in the build (still building), for the price they work ok once you figure what software to use with it.
I used mine when I had a rivet issue early on. It was this one https://www.amazon.co.uk/gp/product/B00KV669US/
I use some thick bailing wire taped to the scope and bent back on itself to get it where I wanted it, took about an hour of fiddling to get it into position but it worked well in the end.
 
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Can some kind soul point me to the section and page in the Kit Assembly Instructions that will show my mechanic where the F-1206F Bearing bracket is located on the RV-12?

We have a kit built aircraft that we bought from the builder, and have the cd with plans/assembly instructions but very hard to find stuff on the cd.

John
 
Look up section 21 Mid Fuse Ribs & Bottom Skins
The info you want is on page 21-03, figure 3. That should get you started, then read the service bulletin.
Cheers,
DaveH
120485
 
My CI is due in July. Will order the parts cause taking the tank out, AGAIN will make it easier to install ADS-B-Out ****!! Thought the split mod was a panacea! Thanks, Brad and John!!

The ************'s are due to the forum nazis!

Isnt the ADSB out just a 2020 GPS replacing the the 250 gps in the sv system? why would the tank come out for that or am I thinking in vs out....
 
We just replaced the bracket in (2009) serial #2 RV-12 with 724 TT on it. Found four cracks after getting some built up lubricating grease/dirt out of the corners. It's VERY hard to see those cracks without carefully cleaning the bracket. And its hard to clean the bracket without being a python - or taking the tank out, which we did.

I'm trying IBB and have no idea why the images are so stinking huge...

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IMG_9381.jpg

IMG_9382.jpg

IMG_9383.jpg

IMG_9384.jpg

IMG_9385.jpg
 
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We just replaced the bracket in (2009) serial #2 RV-12 with 724 TT on it. Found four cracks after getting some built up lubricating grease/dirt out of the corners. It's VERY hard to see those cracks without carefully cleaning the bracket. And its hard to clean the bracket without being a python - or taking the tank out, which we did. Pix to follow if you're interested.

Pictures would be interesting.
 
Enjoyed your story Keith, I also wish to proceed in the same 'Flashman at the Charge' fashion.

You mentioned pulled rivets.....are any solid rivets that require a good bashing? And could the tank have not been removed?

V/R,
Doug


Hi,

I was nervous about applying this mod, and was in two minds about the undertaking while I had the airplane in bits for the annual inspection - there was no signs of cracking, so no obvious requirement to do so at this time. Hamish offered to help and bashed out one mandrel thus committing me to complete the mod. Much of the work described below was undertaken by him, rather than myself as punishment ;-)

Having lost my 1/16 pin punch, we used a #52 drill bit as a punch to extract the rivet mandrels. It worked for the six rivets on the left and right sides of the assembly. Incidentally it also worked for the wing root mod which involved tapping out many more mandrels. I broke the drill bit, but the remaining length was long enough to complete all of these holes. Unsurprisingly the punch I had previously ordered arrived a day later!

Having drilled off the heads of the left/right rivets, we used a #30 drill bit as a punch to remove the remains of the rivets. The drill bit was short enough to get a reasonable swing with a hammer.

The problematic rivets are the four fore/aft ones. I considered attacking them from the rear (looking forward from inside the tailcone) with the 12 inch drill (I had the shop heads on the forward side of the assembly). I also considered cutting the bracket to bits with a dremel, to allow me to get at the four rivets with my 90 degree drill while remaining in cockpit area.

In the event Hamish used a strong pair of snips on the shop heads working from the cockpit area. These broke off the shop head and mandrel together. With some wiggling the bracket then broke free with the four fore/aft rivets still attached.

The replacement assembly, when correctly assembled by following the plans!!!, can be manoeuvred into place relatively easily and pulling the new rivets is the easiest part of the operation.

Having assembled the new parts incorrectly twice (in different wrong ways) I can confirm it is possible to wiggle the bracket into place even when incorrectly built ;-) My thanks to three fellow builders in the UK who offered me their kits to replace my botched up assembly job.

Now done, and I'm happy with the result.

Cheers...Keith
 
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