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  #1  
Old 01-25-2021, 10:58 AM
mikefox mikefox is offline
 
Join Date: Feb 2011
Location: San Jose, CA
Posts: 74
Default SB-00013 slip joint slipping

I'm turning to all the good folks here for some guidance and assistance in performing this SB.

The good folks at VANS have provided a new EX-00021-1 three part exhaust assembly which our team purchased and put on the plane per the instructions. We also installed the EX-00022-1 per the SB which is working flawlessly.

The issue is the middle tube is slipping down and resting on the radiator hose. This contact caused the rubber hose to develop a hole and slow leak which was quickly noticed by pre-flight inspections before each and every flight.

See picture

VANS support said it shouldn't slip, but my co owners aren't so sure this is a good solution to have a slip joint in the exhaust this way.

Has anyone else been successful in installing the EX-00021-1 without it slipping? If so, kindly let me know what I'm doing wrong. Our group strives to follow best practices and compliance with all of VANS Aircraft's recommendations to keep our plane safe and flying well.
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  #2  
Old 01-25-2021, 01:15 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Location: Hinckley, Ohio
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Default

Looks like fire sleeve got a little toasty also...
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Jim Stricker
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PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 633

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father & CFI) - USAAF 1st Lt. Captain B-17H
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  #3  
Old 01-25-2021, 02:59 PM
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Roadjunkie1 Roadjunkie1 is offline
 
Join Date: Jun 2017
Location: Erie, Colorado
Posts: 91
Default Slip joints in exhaust systems

OK: disclaimer: I have not built an RV-12 (which I assume this is; not noted in your post or signature); I am NOT an A&P/IA but have worked on airplanes for decades. But there are several things that I am seeing:

1) Slip joints are very common in exhaust systems, and allow a SMALL amount of movement. Sometimes they are held together with a coupling to keep the movement to a minimum. I don't see one on your exhaust which, I would think, means it needs to be supported some other way to keep the movement to a minimum.

2) I think I see some "exhaust sealant" smeared around the joint similar to some goop WalMart sells, likely in an attempt to reduce bypass exhaust.

3) There is a fire sleeve protecting something (?a fuel line?) that appears to be WAY too close to the hottest thing in your engine compartment: the beginning of the exhaust.

4): The heat shield is resting ON the radiator hose (carrying water, I assume) and is likely what is holding that slip joint together.

I have a slip joint on my (most excellent) Vetterman exhaust system that has that coupling but was also starting to show a little exhaust staining from slight leakage. A JUDICIAL use of an exhaust pipe expander (AutoZone, etc) used on the INSIDE pipe with multiple fit and expand fit and expand trials to get it to seal better. It has been on this RV-4 over 1200 hours.

Fixes (just ideas): MOVE whatever that fire sleeve is covering; drop the radiator hose down some to be further away from that HOT exhaust pipe, heat shield or no; figure out a way to better support those slip joints so they don't move down; Don't seal exhaust with that grey stuff (that was an assumption on my part; I've seen it before: sloppy stuff that doesn't work well).

AGAIN: I know nothing about the construction of an RV-12; these are just things I am seeing as a builder and sometimes mechanic. Other -12 builders/mechanics may have better ideas. Have other -12s had problems like this?

IMHO only; this is strictly an opinion on what I am seeing not an approved method of repair. Good luck!
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  #4  
Old 01-25-2021, 07:55 PM
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rcarsey rcarsey is offline
 
Join Date: Jul 2012
Location: North Brunswick, NJ
Posts: 204
Default

Quote:
Originally Posted by Piper J3 View Post
Looks like fire sleeve got a little toasty also...
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It has something to do with the black rubber in the clamp and the orange material.

My engine hadn't run at all and after a few months of the two rubbers touching each other, the orange firesleeve got discolored. I'm not sure how it happens, but the discoloration seems permanent... and it seems only a cosmetic problem at this point for me.
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  #5  
Old 01-27-2021, 01:44 PM
bernsbm bernsbm is offline
 
Join Date: Nov 2015
Location: Mequon, WI
Posts: 54
Default

I recently installed the new exhaust tubes (EX-00021-1 and EX-00022-2) on my Rotax 912iS and experienced a similar problem. When I attempted to complete Page 48iS/U-07 Step 7:

Grasp the muffler assembly and apply force in the fore-aft direction while moving the muffler assembly side-to-side approximately one inch [25.4 mm] each side of center. This will allow the muffler assembly and all the exhaust pipes to settle into their final "least-stress" positions.

The middle and bottom sections of EX-00021-1 would rotate resulting in the EA LV-1 heat shield resting on the radiator hose. I contacted Tech Support and they suggested two things. First, be sure the muffler is centered, and not positioned more on the pilot side. Second, clock the upper segment of the EX-00021-1 so that the tube will be about 1/2 inch from the cowl. Following their advice resulted in separation between the EA-LV-1 and radiator hose of about 1/4 inch.

After tightening all exhaust stud nuts I test ran the engine for 10 minutes. On rechecking the separation between the EA LV-1 and radiator hose, the gap was 1/8 inch. Tech support confirmed this change from ľ to 1/8 inch was not unusual after engine run, and the 1/8 inch gap was adequate.

Iíve since flown ~1.2 hours and on recheck the 1/8 inch gap is unchanged. Iíll be checking again after my next flight to confirm everything is stable.

Hope this is helpful.
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  #6  
Old 01-27-2021, 02:01 PM
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Piper J3 Piper J3 is offline
 
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1/8" is not very much clearance - that would make me nervous. I don't think anything on my 912ULS is that close to causing interference and rubbing.
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Jim Stricker
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 633

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father & CFI) - USAAF 1st Lt. Captain B-17H
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  #7  
Old 01-27-2021, 04:24 PM
bernsbm bernsbm is offline
 
Join Date: Nov 2015
Location: Mequon, WI
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I agree 1/8 inch is close. Van's technical support just called me in follow up and relayed the target gap should be 5/16 but no less than 1/4 inch. They confirmed this can be achieved by proper clocking of the exhaust tube.

Guess I have some more adjusting to do!
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N12BB RV12 Skyview flying since Oct 2016 (Sold)
N122B RV12iS Garmin flying since Oct 2020
https://eaabuilderslog.org/?s=bbernstein
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  #8  
Old 01-27-2021, 04:51 PM
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jrtens jrtens is offline
 
Join Date: Apr 2018
Location: Utah
Posts: 142
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You might want to put some heat shield material on the radiator hose in case the pipe slips down inflight.

https://smile.amazon.com/Thermo-Tec-...s%2A=0&ie=UTF8
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  #9  
Old 01-27-2021, 08:24 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 2,921
Default

A similar issue is the oil line that taps into the forward right side of the engine. It is very close to the exhaust pipe. At the time (a few years ago) there was debate about putting exhaust wrap on the exhaust header and how it might promote early failure of the exhaust pipe. I took the exhaust wrap from Auto Zone and wrapped the oil line which was already fire sleeved. My 10 year replacement is due in March 2022, and I have had no problems.
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  #10  
Old 02-26-2021, 02:27 PM
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greghughespdx greghughespdx is offline
 
Join Date: Nov 2011
Location: Aurora, OR
Posts: 925
Default Van's will be replacing lower segment of the #1 exhaust tube assembly

For those who have received the RV-12iS #1 tube parts either (specifically, the assembly with 3 sections that make up the #1 tube), we will be instructing customers to remove and destroy the lower-most one-third segment of the assembly and replace that tube segment with a replacement lower tube segment that we will provide, and which is in flight testing now. We do not have the exact timeframe to share yet, but this is being actively worked on. Only one of the three segments has actually changed, so for those who have received the three-part tube assembly already we are planning to replace the lower 1/3 tube segment, unless the airplane has already flown with the problematic three-tube setup - in which case we'll replace the entire three-tube assembly. A bit complicated, I know. And we know this has been frustrating for a few people, and that the manufacturing process is a bit slow for this due to the complexity of the bends, materials, etc. - but we are working on it actively and have made a significant investment in new tube-bending equipment that will result in better and more-capable future manufacturing, as well.

Note that is issue affects only the RV-12iS - The original RV-12 is not affected.
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Last edited by greghughespdx : 02-26-2021 at 02:35 PM.
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