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New Service Bulletin 00053

Greg,

It looks like (24) LP4-3 rivets are required to replace the ones drilled out. Are all the rivets used in this SB LP4-3?

The SB-00053 Installation Kit does not list the rivets as included. The service bulletin does not list the rivets in the list of “materials required”. Do I order rivets or not?

It says you get a bag of 30 LP4-3's.. They are contained in the Bag 1910 which is included in the SB-00053 Kit.. I placed my order last night..
 
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Do I have to order this if I'm still building? Or do they send it out automatically?

I built the tail in Oct. 2020.

still waiting on my last kit "finish kit"
 
There's ADHARS and antennas back there, not shown in the diagram provided if your RV-12 is Skyview equipped, if I remember correctly from my last inspection.
 
I'm with Steve and Jim. I wish Van's would re-think this repair/SB. I am not an engineer but the "clips" do not look robust enough and I suspect cracks will form even with the clips installed. I'm in favor of the external doublers cracks or not.

I would like to apologize to all of the engineers at Van's for my post. Especially the "re-think" it part.
I'm quite sure you guy's thought it through. I broke my own rule and posted out of frustration. I had just finished closing up after my first C.I. I also had the fuel tank out and now fact is I have to go back in....
Again, my sincerest apologies,
Jack
 
Almost seems like a doubler plate could be added on outside of skin similar to triangle plates on bottom of aircraft near wing center section. Crack appears to be in the skin and not the bulkhead. Otherwise, I have to find a 10 year-old kid to crawl into tail cone...

I’m with you Jim. Why not just put three doublers on from the outside and be done with it, cracks evident or not.

I'm with Steve and Jim. I wish Van's would re-think this repair/SB. I am not an engineer but the "clips" do not look robust enough and I suspect cracks will form even with the clips installed. I'm in favor of the external doublers cracks or not.

I’m 78 and understand, I wonder if Vans would entertain adding a couple inspection plates in that area.
My Bonanza and Cessna has them in that area. That’s an area that needs to be inspected regularly anyway.

Not a Boeing engineer but as Greg Hughes said, the issue is the lack of continuity of the bottom J stiffener either side of the bulkheads which interrupts the load path and also creates a sudden change in stfffness locally which allows flexing of the skin and leads to fatigue cracking. There are cutouts in the bulkhead in other locations to allow the stiffeners to pass through, but not on the bottom skin.

A patch would make sense for the skin tension loads, but looking at the crack, it seems to look like the bending was across the skin contact points indicating a vertical shearing load parallel to the plane of the bulkhead. The clips will stop that though rivets in the clips putting those rivets in shear. In this context look closely at the cracks in the bulletin and see if you agree.

Not that it is necessary to agree, because I would have high confidence in the FEA performed by Vans Engineers.
 
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The aluminum skin in that area is not flat, I don't understand how a piece of plywood will fit in there and not cause marks on the skin when the weight of a person is applied.

I have about 2 x 6 feet of green, HD foam (5" thick) from a fabric store that my wife made cowl plugs with. I was think about using that with the plywood on top, as I had the same concern about straight-up plywood after looking at the area in question.
 
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has anyone made the plywood pieces? If so would you share the dimensions?
Also are all the rivets drilled out from inside the tailcone or are some drilled from outside?
Alan
N603NH
 
Question for Greg Hughes - out of the 750+ RV-12's flying, can you tell us how many aircraft owners have reported cracks in these areas?
 
I might be out of place saying this but I am trying to understand;

SB-00023, a possible crack in a engine mount standoff is an "inspect every 100 hr item or replace".

SB 18-02-03, anti servo skin cracks - "If no cracks are detected, re-inspect at every annual condition inspection or until the
modifications required by this service bulletin have been completed".

SB-00053 for the tail cone skin cracks;
The ONLY compliance is to install the clips even if no cracks are found.

The first two SB's above feel like that they could crash an airplane if cracks occur, and the engineers give the option to hold off repair by continuous inspection.

This current tail cone SB doesn't seem like a safety of flight issue even if a crack occurs between the rivet holes, but the engineers say add the clips within 100 hours regardless.

What am I missing?
 
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Hi All
just a couple of questions,i understand the sb has to be done at some stage but is sufficient to inspect to see if you have any cracks on the outside , and secondly vans say to put plywood in between the stiffeners to work assuming you are under 200lb but i wouldn’t risk damage to the skins i plan to support the skins under the bottom with a timber plank and carpet on top what are you guys planning? will you be trusting the skins with plywood protection
 
Vans say to put plywood in between the stiffeners to work assuming you are under 200lb but i wouldn’t risk damage to the skins i plan to support the skins under the bottom with a timber plank and carpet on top what are you guys planning? will you be trusting the skins with plywood protection

I plan on working up my nerve to "go in" like doing surgery, but I'll wait for warmer weather. I plan on using 4" thick EPP Expanded Polypropylene instead of plywood. The 4" thickness should be taller than the bulkheads thus preventing damage as a scurry around in the tail cone like a hamster...
 
It's my understanding that Service Bulletins are not mandatory.

From the FAA Aviation Safety website: If you are
operating your aircraft under 14 CFR part 91, a
service bulletin is advisory, and compliance is not
mandatory unless it is included in an Airworthiness
Directive. Keep in mind that even when a service
bulletin is not mandatory, you should always pay
attention to it as a means to ensure your safety.

Please correct me if I'm wrong.
 
It's my understanding that Service Bulletins are not mandatory.
From the FAA Aviation Safety website: If you are
operating your aircraft under 14 CFR part 91, a
service bulletin is advisory, and compliance is not
mandatory unless it is included in an Airworthiness
Directive. Keep in mind that even when a service
bulletin is not mandatory, you should always pay
attention to it as a means to ensure your safety.
Please correct me if I'm wrong.

You are correct.
Having said that, one must consider the practical side.
When you sign off a condition inspection, can you, in good faith, say that the aircraft is "in a condition for safe operation", if it has an outstanding Service Bulletin?
 
Yes, I believe I could say that if I see that there are no cracks developing during future frequent inspections.
I have concerns that someone climbing into the tailcone could actually cause additional damage to a light skinned aircraft such as this.

Personally, I'm going to hold off until Vans provides additional information.
 
It's my understanding that Service Bulletins are not mandatory.

From the FAA Aviation Safety website: If you are
operating your aircraft under 14 CFR part 91, a
service bulletin is advisory, and compliance is not
mandatory unless it is included in an Airworthiness
Directive. Keep in mind that even when a service
bulletin is not mandatory, you should always pay
attention to it as a means to ensure your safety.

Please correct me if I'm wrong.

Your insurance company may not pay a claim if SB's not complied with...
 
Maybe Van's should consider alternative tail cone designs for the RV-15? I've attached one that should work for the over 70, overweight, over height crowd (note I hit 2 out of 3 on that list :)
 

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So, I spent the day on a creeper, SB-00053 in hand, laying under the tail cone of my airplane. I gotta say folks, I see no way that this 68-year-old, 170 lb, 5'10" guy is going to get this done.

I think Van's owes us some further tips and guidance on how to accomplish this SB. They obviously "proofed" the process. How about some lessons learned? The SB is pretty skimpy on guidance.
 
So, I spent the day on a creeper, SB-00053 in hand, laying under the tail cone of my airplane. I gotta say folks, I see no way that this 68-year-old, 170 lb, 5'10" guy is going to get this done.

I've been looking for a video of someone removing high-pressure fuel filters from behind baggage bulkhead on a 12iS... :eek:
 
You should assume that, since it's true. :) SBs like this one are based on real-world experience and careful, detailed studies performed by our engineering team, including stress/fatigue modeling and analysis.


The J-stiffener feature in the RV-12 tailcone provides stiffness in the skin and a load path. Since that feature (the J-stiffener) is discontinuous at the bulkhead in the original design, there is flexing occurring at the bulkhead area. The clips in the SB kit are installed to make that J-stiffener structure continuous. This provides a continuous load path through the bulkhead to increase stiffness and prevent the flexing of the skin at the bulkheads.

So, a doubler will not address the issue. It might prolong the time it takes to form a crack. Maybe. And, it very well could transfer undesirable loads elsewhere.

Install as described. This is all part of airplane ownership - maintenance and ongoing improvement based on field experience is the second half of design quality and safety. Our team doesn't guess at these things, they engineer them. We won't be telling anyone it's ok to install differently than the SB design specifies.

Ok, understand the root cause is the discontinuity of the J-stiffener. Given the difficulty of the fix, please tell us you looked at an "external strap" (not a plate doubler) of considerable thickness as an alternative to fixing the discontinuity. If you did, fine. But you owe us that answer.
 
For what its worth, I had to run my NAV antenna inside the cone after completion (the nav install was part of the avionics subkit which came long after the airframe assembly steps).

Getting my hands all the way back.. essentially.. to the rear bulkhead/doubler plate to ziptie that coax in place was very difficult for me (5'10" 200lbs) and I had to get another builder to do that step. (it also entailed some drilling).

For this SB, getting to the rearmost bulkhead for this will again be difficult for me. My plan is to use pink rigid insulation foamboard from Home Depot (in lieu of the plywood) and build up enough layers so that I do not need to worry about my weight being put on the bulkheads as I venture into the bowels of my -12. The "soft" edges of the foam should help to ensure I don't somehow put dents or creases in the skins. And its very easy to shape the foam according to the bottom skin dimensions.

A small clippy fan will help keep things a little more comfortable inside.. conditions tend to get quite warm and steamy while working. A helper with his own pull-rivet gun, cleco/pliers under the tail will be very beneficial too. The last thing you want to do is to have to make multiple trips into the cone.
 
I've been looking for a video of someone removing high-pressure fuel filters from behind baggage bulkhead on a 12iS... :eek:

I just replaced my 12iS Rotax fuel filter (after the first 100hrs per Rotax inspection schedule). It was fairly easy -- I didn't feel it warranted its own video..

One question that came up though is whether the metal/rubber washers are reusable (the ones that Van's sent us, in place of the Rotax copper crush washers). Support said if they look good, OK. BUT, they are cheap.. so why not get new ones. Oh, and more fuel leaked out of it than I expected.
 
I'm very surprised that the skins alone can support 200lbs- makes me more confident in that little airplane. I'm at 190lbs and not getting lighter as I age, so glad I haven't received my tail kit yet. :D

The good news is that the kit is $30 and should take a day or less. If this was on a Cessna I bet the parts would be $500 and the A&P labor would be another $1,000.....sentiment coming from a guy who just had to replace seat rails and several seating components on a 172. Sticker shock doesn't do that job justice. Haha.

Good luck everyone.
 
My plan is to use pink rigid insulation foamboard from Home Depot (in lieu of the plywood) and build up enough layers so that I do not need to worry about my weight being put on the bulkheads as I venture into the bowels of my -12.

Apologies if I'm wrong, but I don't think you need to worry about some weight being put on the bulkheads. I believe the plywood is just designed to distribute any weight that you put on the skin over a larger area to prevent damaging the skin. In order to get this SB completed I think we will just need to slither into the tail cone like a snake. I expect that once you get to the far back bulkhead you will have some of your body weight across the two forward bulkheads and the skin between the bulkheads.

My plan is to use either plywood or think foam as described by others and then throw a couple of thick blankets across all the foam and bulkheads. Lastly I'll probably put some cardboard over all of it, to make it easier to slither to the back. :)
 
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Joe, I’m pretty sure you CANNOT put any weight what so ever on the bulkheads. Crush one of these, and it’s game over for your tailcone.
 
I went out to the plane today and inspected the bottom of tail cone for cracks and found none. Skins look like the day they were painted. My plane is early SN with TT = 750 operating from pvt grass strip. As mentioned in a previous post, when ground is soft, I pull the airplane back into the hanger with a winch attached to tail tiedown hook. I’m glad to see no cracks.

So, I stood to the side of the airplane and tried to visualize myself crawling head first into the tapering tail cone. I thought about how I would work up my nerve to "Go In" like a surgeon and ended up feeling squeamish thinking about scurrying around in the tail cone like a hamster...

My plan is to buy the SB kit and sit tight. I’m going to wait 100 hours which will put me into fall timeframe and near Annual Condition Inspection. If inspection again shows no cracks, I might put this SB on Condition Inspection like the WD-1221 Engine Mount Standoff where 100-hour inspections are required. I can even incorporate the visual inspection into the pre-flight routine and add item to the checklist.

As a side note… I wonder if some of these planes are being severely abused, perhaps in flight training. Case-in-point is Kathryn’s Report from just two weeks ago where RV-12 in New Hampshire landed hard and gear collapsed.

Just say’n…
 
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I went out to the plane today and inspected the bottom of tail cone for cracks and found none. Skins look like the day they were painted. My plane is early SN with TT = 750 operating from pvt grass strip. As mentioned in a previous post, when ground is soft, I pull the airplane back into the hanger with a winch attached to tail tiedown hook. I’m glad to see no cracks.

So, I stood to the side of the airplane and tried to visualize myself crawling head first into the tapering tail cone. I thought about how I would work up my nerve to "Go In" like a surgeon and ended up feeling squeamish thinking about scurrying around in the tail cone like a hamster...

My plan is to buy the SB kit and sit tight. I’m going to wait 100 hours which will put me into fall timeframe and near Annual Condition Inspection. If inspection again shows no cracks, I might put this SB on Condition Inspection like the WD-1221 Engine Mount Standoff where 100-hour inspections are required. I can even incorporate the visual inspection into the pre-flight routine and add item to the checklist.

As a side note… I wonder if some of these planes are being severely abused, perhaps in flight training. Case-in-point is Kathryn’s Report from just two weeks ago where RV-12 in New Hampshire landed hard and gear collapsed.

Just say’n…

I agree 100%.

I detail clean the underside a minimum of every 25 hours and will give extra attention to this area.

I am a bit confused why Greg or Scott have been so quiet on this issue. There are many questions being asked in this thread, they should address them.
Why it is this a mandatory repair even if no cracks are visible?
Show us how to support the tail cone skin to prevent additional damage from climbing inside.
What is the history of this SB?
Are we risking a crash if there is a 1" crack in this area?
 
Ok, understand the root cause is the discontinuity of the J-stiffener. Given the difficulty of the fix, please tell us you looked at an "external strap" (not a plate doubler) of considerable thickness as an alternative to fixing the discontinuity. If you did, fine. But you owe us that answer.

We considered a wide variety of methods to address this. An external strap does not address the issue. Adding more skin structure doesn't resolve the actual problem. The need here is to prevent the problematic flexing of the skin in the first place.

I am a bit confused why Greg or Scott have been so quiet on this issue. There are many questions being asked in this thread, they should address them.
1) Why it is this a mandatory repair even if no cracks are visible?
2) Show us how to support the tail cone skin to prevent additional damage from climbing inside.
3) What is the history of this SB?
4) Are we risking a crash if there is a 1" crack in this area?

We're pretty busy right now with a lot of work that we have to balance, so our apologies if we don't reply in a timely manner every time. The clips in the kit are pre-bent, the rivets are pretty easy to drill out, and it's all pulled rivets to install the new parts. Yes, getting in the tailcone is a bit awkward. To address your questions:

1) For SLSA it is mandatory. For ELSA and EAB you have the power of discretion. Cracks will eventually form. Every airplane is a little different. It will vary from one aircraft to another in terms of how long it will take, and whether you'll see them when they start to form.
2) To be honest, I think people are overthinking this a bit. Put a tail stand in place so the tail won't strike the ground when someone's in the tailcone. And the idea with the plywood is to prevent a knee or other body part from applying concentrated stress on a skin. The plywood described in the bulletin spreads the load over a large area and accomplishes this. If you want to use dense foam or some other method, your choice. I'll ask our engineering team for some additional input on this and see what they say.
3) It was just issued. Aircraft with both very low and very high hours (and in-between) have been found with similar cracks in the same locations. Engineering analysis says cracks will eventually form. Parts to address the stress concentrations and load carry-though were issued. Service bulletin and parts were released.
4) There's no way to answer that question for every airplane equally. A crack is not a crack is not a crack. It depends completely on the loads applied to the airplane with the 1" crack, where exactly the crack is located, and a bunch of other hypotheticals/variables. Once a crack starts, it represents a structural failure which was predicated by the discontinuity in the J-stiffener and the resulting transfer of loads into the skin/rivets. The whole point here is to prevent the cracking. Once the skin has cracked, the skin's remaining ability to handle these loads is diminished. The important point here is that we are installing new parts with this SB to remove the problem loads from the skin itself. It can only get worse one it starts, and how much worse is the variable. It depends. The stresses on the top and bottom of the tailcone can be quite high, and if there are discontinuities and/or cracks where the load concentration is highest, it needs to be addressed. Proactively. That's why we issued this bulletin.

Note that we don't do risk analysis based on hypotheticals, and we certainly don't issue SBs for fun. We engineer and issue SBs to cover the potential risk for a fleet of aircraft based on real-world experience. Will your airplane fall out of the sky if there's a one-inch crack? That depends on a lot of things. We'd very much prefer to have you execute this simple SB rather than find out the hard way.

I'm an RV-12 owner with pretty bad arthritis, so I share in the awkward pain of climbing in a tailcone. If it's difficult physically for someone to get in the tailcone, I'd say get a helper. Teenagers work cheap and maybe you'll introduce someone new to experimental aviation. It's inconvenient, but not really all that difficult to get back there... That said, I know I sure wouldn't want to do it every 100 hours (as some have suggested they might do instead, and we do not advocate that) just to inspect, and please note that it needs to be inspected from inside, not just from outside. When you review the SB you'll see the cracks in the photos are from inside the aircraft. And, when you climb back there once and you get the parts installed, you're done.

We appreciate the feedback, and we review it and consider it for context when creating the next SB or when adjusting an existing one.

Hope that helps.
 
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Thanks Greg, for the more thorough explanation.

If you were only addressing certified owners then I agree you don’t owe us an explanation. This type of factory interface is what makes Vans stand out among the other kit plane manufacturers. Don’t ever think it is unnecessary.
 
...I'd say get a helper. Teenagers work cheap and maybe you'll introduce someone new to experimental aviation...

Might I suggest checking with your local EAA Chapter to see if there are any Student Build RV-12 Projects they're mentoring? Our Chapter, EAA 75, is just about finished our tailcone. I'm confident we have quite a few students that would be very competent in performing this SB...and fit inside the tailcone very well. Bad news for us is we just closed the tailcone skins about 3 weeks ago...timing for this was JUUUUUSSST a bit late to make it super easy for us.

I'll let you all know how it works out when we get our SB kit to apply.

-Greg
 
I'd be inclined to offer a teenager an exploratory flight after the work is done, in exchange.

Something to think about.
 
My concern with a teenager or anyone else with low experience in that tight space, arms extended, looking at it from an angle and trying to drill out the lower bulkhead rivets (3). What if they miss center, or are at an angle and they over drill one of the holes creating a serious repair issue.
 
Greg, not sure if you saw my question or not.

Sorry, I meant to reply before and apparently forgot to! I don't personally know the exact number. I know it's at least a handful of actual aircraft for certain, and that the specific pattern was proven repeatedly both in discovery of real-world cracks and via analysis, and that this was determined to be a "when" rather than an "if" type of problem. Hope that helps.
 
When I was working inside of the tail cone of my 6A, I took a bean bag and removed 1/2 of the beans and placed them in a king size pillow case and sealed the end.

The now 2 bean bags filled in the belly to over the bulkhead. One on each side. I then laid cardboard on the bean bags to make it easy to slide in and out.
It turned out to be very comfy.
 
Disappointed

When I was working inside of the tail cone of my 6A, I took a bean bag and removed 1/2 of the beans and placed them in a king size pillow case and sealed the end.

The now 2 bean bags filled in the belly to over the bulkhead. One on each side. I then laid cardboard on the bean bags to make it easy to slide in and out.
It turned out to be very comfy.

No lame jokes about “spilling the beans” yet?
Y’all are pitiful (grin)
 
Will buy a beer at Oshkosh for the first guy who posts accurate measurements of the various plywood/foam rectangles for this SB. (sure would like to cut them out in advance of crawling in there later this spring.)
 
Will buy a beer at Oshkosh for the first guy who posts accurate measurements of the various plywood/foam rectangles for this SB. (sure would like to cut them out in advance of crawling in there later this spring.)

I'm planning to get this for you as soon as we have a little time. My airplane happens to be apart right now for other reasons, so getting these from an actual airplane should be not too difficult. It may just take a few days or so before I can do it.
 
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