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RV-12 Service Bulletin 19-03-22 Published - Possible cracks in #2 exhaust tube

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greghughespdx

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Document Name: Service Bulletin SB 19-03-22
Effective: May 21, 2019
Subject: Cracking of the EX-00017 Cylinder #2 Exhaust
Affected Models: RV-12 with 912 ULS engines
Affected Serial Numbers: All RV-12 model aircraft (RV-12iS is not affected)
Required Action: Inspect the EX-00017 Cylinder #2 exhaust tube for cracks as described in this document. If cracks are found, replace the EX-00017 with an EX-00017-1.

Van’s Aircraft has released a Service Bulletin (SB 19-03-22) affecting all RV-12 aircraft equipped with a Rotax 912 ULS engine and a specific configuration/version of the Cylinder #2 exhaust pipe. Depending on when the RV-12 firewall-forward kit was produced, there are three possible designs for the Cylinder #2 Exhaust Tube. Only one of those designs (EX-00017) is affected by the service bulletin. Inspection is required in order to determine which specific part is installed on an individual aircraft.

Data from the field suggests that some EX-00017 Cylinder #2 Exhaust Tubes are prone to fatigue cracking. If the pipe fails, hot gases from the exhaust may eventually compromise the composite cabin heat duct, which could in turn result in the introduction of dangerous exhaust gases into the cabin if the cabin heat door was open. Complying with this service bulletin will ensure aircraft equipped with affected parts are furnished with a sufficiently robust part, equivalent to aircraft equipped with newer parts.

Before further flight, owners are instructed to inspect their aircraft to determine which part is installed, and in cases where the affected part is installed to either replace the part with a new part available from Van’s Aircraft or to equip the aircraft with a carbon monoxide detector and then inspect the affected part at regular intervals. If a cracked pipe is found, the new part must be acquired and installed. Note that once a crack develops in the affected part, it is likely the exhaust pipe will fail quickly. Therefore, regardless of whether any cracks are observed, Van’s Aircraft recommends that any affected part be replaced proactively, to avoid the possibility of a crack-related failure. The use of an aviation-grade carbon monoxide detector prior to replacement is an option, but should not be considered a long-term solution.

Photos of the affected part are included in the service bulletin document, in order to aid in identification and to help determine whether or not the installed part is the one covered by this bulletin.

RV-12-912ULS-Exhaust-Variants-Web.jpg
 
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Hey Greg, my FWF kit was shipped April 2010. Any idea of which pipe came during that time period? Just being lazy about pulling the cowl.
 
Hey Greg, my FWF kit was shipped April 2010. Any idea of which pipe came during that time period? Just being lazy about pulling the cowl.

Hi John. Sorry, but no. Given the importance of knowing for certain, the only way to properly/safely check is to actually take a look. You may only need to remove the top half of the cowl and use an inspection mirror, but the best way is to remove both halves.

Knowing for certain which part is installed is the main need.

greg
 
$230 for the new part. A bit pricy! I hope mine is not the affected revision. Will check sometime in the next two weeks and keep my fingers crossed!
 
$230 for the new part. A bit pricy! I hope mine is not the affected revision. Will check sometime in the next two weeks and keep my fingers crossed!

That point was raised a couple of times this week in discussions with customers about this SB. We probably should have stated in our initial post here that Van’s is providing this part, which is somewhat complex and labor intensive to manufacture, at-cost to owners who are replacing affected parts.

A couple other questions we've answered this week:

Q: Have there been actual cracks of this pipe occur in the real world?
A: Yes, on at least two occasions we have observed a failure of this exhaust pipe section, which resulted in burn damage to the engine cowl at the air inlet tunnel, which provides cabin heat.

Q:What’s the worst thing that could happen if this pipe fails?
A: Failure of the exhaust pipe could result in hot exhaust gases eventually burning through the air inlet duct in the cowl, which would result in the introduction of exhaust gases and carbon monoxide into the air inlet duct, and potentially in turn into the cabin of the aircraft where it could affect occupants.

Personal statement, made as an individual: I happened to be the pilot of an RV-12 in one of the two occasions mentioned in the above above point (this was not one of the company-owned airplanes). I was able to recognize the occurrence of the failure, determine what was likely happening, and get the airplane safely on the ground before things got too much worse. I did have to repair the fiberglass cowl/duct in that case and the inlet duct material, although substantially heat damaged, had not burned all the way through. That said, had I not recognized the occurrence in a timely enough manner, the outcome could have been different. So, from personal experience I'd suggest - as an individual aircraft operator and pilot - that a taking the proactive approach on this (replacing the affected part) is in my opinion a smart, reasonable and relatively small price to pay. Heck, you don't even want to know how many AMU's it cost me a couple years ago to replace an exhaust section that had failed on the certified spam-can aircraft I owned! And, I replaced that same part twice in a 10 year period! I'm still trying to wipe those expenses from my memory!
 
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HUM---a good tube bender could make those bends without the welded section. Maybe Clint will chime in.

Tom
 
RV12 exhaust

I posted about an exhaust some time ago,the story is I had an exhaust break, at a weld on a Long Eze. It caught the cowling on FIRE.Probably on taxi in. The eze was saved. My point is: exhaust can ignite fiberglass, to me this the most serious aspect of replacing the pipe! Ben
 
I?ve no experience with wrap, but have been told it cuts down the heat greatly.

Do not wrap the RV-12 exhaust. It's not manufactured not intended for that. And, it would have no impact related to the issue described in the SB, other than to make it basically impossible to examine the pipe itself.
 
Like ?Benfra? I had a separated exhaust header on another homebuilt. It was a War FW-190 with a fiberglass covered wood airframe. It took me about 20 minutes to reach an airport. My cockpit smelled like a barbecue pit, but fortunately I only had minor charring at the edge of the firewall. That plane looked great, but it was responsible for a lot of ?experience?.
 
When I received my powerplant kit from Van's in June of 2015, I received one of the very first kits with the revised exhaust system that moved the muffler a little further aft. So if the powerplant kit was received much prior to that date, the exhaust pipe will not be the EX-00017 pipe shown with the issue.

I have no clue when the newer EX-00017-1 pipe began shipping in the powerplant kits.

Because my RV-12 has the EX-00017 exhaust pipe in question, for piece of mind and safety, I just placed an order for the revised EX-00017-1 exhaust pipe and will replace the affected pipe.

Happy flying,
 
Everyone,

Please be advised, the only proper way to check your aircraft to determine whether the affected part is installed is to remove the cowl and take a look. You only need to remove the top cowl half, which takes less than five minutes, and grab a flashlight to see the whole pipe.

Shipped before/after dates can help determine likelihood of which part is installed, but do not guarantee an accurate answer. The only way to accurately and reliably check, is to check. Failure to check the aircraft means non-compliance with the service bulletin.

Just want to be very clear on that point! It only takes a few minutes of time and a Phillips screwdriver to complete the part inspection.

Thanks,

greg
 
It figures....

Of course I have the affected part!! Let me first say that I appreciate Van's selling this to their customers at their cost! Not happy with Rotax!! I just ordered the new version at $230 plus tax/shipping. After only 140 hours in my first 2 years, it's ridiculous that a customer should pay for a defective part, especially on the heels of my overweight carb floats! I don't care about the labor cost (most of us do it ourselves anyway) but everyone that has this bad exhaust pipe should be reimbursed by Rotax :mad:

For reference, my FWF kit was packed/shipped in Dec, 2016. The packing list does not show the individual pipe part numbers, so you really have to visually inspect as Greg pointed out. I would really like Van's to push this issue with Rotax, it's just wrong and it's about $30 worth of pipe/welding! Sorry for the rant, it's not the money, definitely the principle.

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Hi Paul, sorry to hear you have the affected part. But, are we sure it is a Rotax problem?
The Rotax 912 is installed in a million (OK, maybe hundreds) different airplanes with a variety of exhaust arrangements. I can't imagine that Rotax builds all these different pipes. Maybe the aircraft manufacturer sources just the end pieces from Rotax and the rest of the pipe is welded up by someone else to fit the application?
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Hi Paul, sorry to hear you have the affected part. But, are we sure it is a Rotax problem?

That's a good point Tony, and I did think about that, I was just hoping to find out via the rant who the actual vendor was. Just like the carb floats are more of a Bing issue (I assume) but Rotax needs to step up on that one. Just frustrated....like I said, probably about $30 worth of time and materials to make the replacement pipe. Normal usage/wear/tear is one thing, but a defective part....all involved vendors should step up. But you're right, this one may have nothing to do with Rotax!
 
I suspect that this pipe is a Van's vendor-supplied part unique to the RV-12 series. Wouldn't it be less costly (as a user option) for the vendor to weld a patch over the weak area of the EX-00017 pipe using the original jigging? Perhaps Van's could offer to exchange a failure-prone EX-00017 pipe for a vendor-repaired replacement pipe that is similar to the EX-00017-1?

Fortunately, my older (#120496) RV-12 has the original EXH-1202 pipe and I am OK for now. We'll see ...
 
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Wouldn't it be less costly (as a user option) for the vendor to weld a patch over the weak area of the EX-00017 pipe using the original jigging? Perhaps Van's could offer to exchange a failure-prone EX-00017 pipe for a vendor-repaired replacement pipe that is similar to the EX-00017-1?

I think that's a great idea Dave, I hate to just remove what appears to be a good exhaust pipe (currently) and just throw it in the trash!! (along with $230) Maybe an exchange program where those with the bad pipe could be sent a repaired version (to reduce downtime) and send in the bad pipe. If the user doesn't send in the old pipe in a reasonable amount of time, they could be charged full replacement price. I would certainly prefer that to throwing it away. Thanks for the thought :)
 
A number of the parts for the exhaust system (including this #2 tube assembly) are sourced from Rotax and then welded into assembly at Van's by our team. We are selling the part at our cost of materials (Rotax supplied and otherwise) and labor in this case, a decision that was made specifically because of the fact that we have seen two of these fail in the field and we believe it's in the best interest of aircraft occupants to have the reinforced part. We're certainly not making any money off the replacement pipes, and we actually put quite a bit of time and effort (not built into the cost of the part) into testing whether or not we could reliably produce one standard pipe that would actually fit on flying airplanes consistently. The entire exhaust assembly sells for more than $1200. Complete replacement of the exhaust system has always been the required approach when an exhaust repair has been needed in the past, so in this case we worked to reduce the impact of this particular part change.

All of the ideas being discussed (and a few more) were discussed here at Van's. We cannot take a used pipe on exchange and patch it and then send it to someone else. And sending a patch to the aircraft owner and having a reliable weld made is not something we determined could reliably work. The patches would have to be custom formed to the pipe, which is a time consuming and costly process to get right. The heat-affected zone as a result of welding these pipes requires special attention, to ensure the final result is safe and meets critical specs.

Exhausts are "wear" items, of course. There's a lot of vibration and heat and other forces at play. It's common to need to replace worn or cracked exhaust systems and components on aircraft. And they're never inexpensive, but in the RV world they're at least reasonable. The exhaust on my certified airplane is ridiculously expensive to replace parts on - much, much more so than any exhaust system on any RV! The last part I had to replace on that airplane was a simple curved shield with a small screen welded on, and it was more than triple the cost of the pipe in question here.

So, we understand the frustration but please realize that we've done all we can to make it as reasonable as possible to take care of this item. Our goal here is to tell you about the issues we have seen in the field on the aircraft where the exhaust has cracked, so you can address the problem proactively. We do so in the interest of both safety and transparency, as we care about our customers and value providing you useful information you can act on.


[ed. $230 change that can keep CO from filling your lungs. I'm pretty sure this 'ol thread has run it's discussion course, so I'll close it up now. Greg, thanks to you and the mothership for looking out for us and thanks for the solution.

SB 19-03-22

"Learn it. Know it. Live it." --- Brad Hamilton (movie quote)

https://www.vansaircraft.com/service-information-and-revisions/sb-19-03-22/

v/r,dr]​
 
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