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Broken Exhaust Hanger ? and a Temporary Fix

Ironflight

Ironflight

VAF Moderator / Line Boy
Mentor
During my recent post-trip maintenance on the Valkyrie, one little problem I found was a broken end on the horizontal exhaust hanger. On the RV-8, you have two links that angle back and down from oil pan bolts to support the exhaust pipes, and one cross-brace that holds them apart. Each of these three links is made from a piece of reinforced rubber hose and two ?ends? made from a piece of 3/8? stainless steel tube with the end crushed flat and drilled.

I was frankly quite amazed to see that the hole in one of the ends of my lateral link was worn and pulled through! And if you think the link looked bad, you should have seen the Cad-plated bolt that did battle with it! Both were toast, and needed replacement.

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Since these parts come with the Vetterman exhaust systems from Van?s, I wasn?t sure if Van would have the ends, so I gave Larry Vetterman a call direct. ?Sure, I?ve got some of those ends, I?m looking at a box of 367 of ?em right here!? was his response. ?I could bring a couple of ?em to LOE this weekend if you want.? How could I turn down an offer of personal delivery? That sounded great ? but with the broken hanger, how was I to get the airplane there?

?Really simple? he said. ?Go to the hardware store and get yourself a piece of 3/8? copper tubing ? aluminum will work, but copper is twice as strong ? not as good as steel, but it?ll last long enough for a trip like that, easy. Cut it to length, smash it carefully so as not to create any sharp stress risers, drill the hole, and you?re all set!?

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So ? if you find yourself with worn out exhaust hanger ends like I did, don?t despair ? Larry has replacements ? and you can make a temporary with a trip to your Ace Hardware and Aviation Supply Store. They?re likely to give you six inches of the stuff ? don?t bother with Home Depot ? they only want to sell a 20? coil!

Paul
 
Amazing that the stainless tubing (probably 304SS or similar would be my guess) and the bolt would grind themselves into oblivion yet the rubber hose would be unscathed.
 
Lars said:
Amazing that the stainless tubing (probably 304SS or similar would be my guess) and the bolt would grind themselves into oblivion yet the rubber hose would be unscathed.
Click to expand...

Good point. Paul, is it possible you didn't leave a large enough gap between the two stainless tubes (where they meet inside the rubber hose)? Or perhaps they moved closer over time due to the hose clamps getting lose? It seems to me that if the two stainless tubes were bonking against each other inside the rubber hose then it could cause this.
 
kevinh said:
Paul, is it possible you didn't leave a large enough gap between the two stainless tubes (where they meet inside the rubber hose)? Or perhaps they moved closer over time due to the hose clamps getting lose? It seems to me that if the two stainless tubes were bonking against each other inside the rubber hose then it could cause this.
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That's a good question, and while they are close, they don't touch. Of course, 1200 hours probably has something to do with the wear....:rolleyes:
 
Good Point - These need to be regularly checked

Paul:
Looks like the fastener wasn't clamped tight enough and was allowed to work back and forth in the joint. I've had a couple of these fracture as well, but at the point the tube end was crushed. Clamped tight enough, the bend point is taking all the load. In any event, there's a lot of movement with the pipes - any closer than a 1/2 inch of the engine mount on a nose dragger and they're banging against it. Glad you pointed this out.
Terry, CFI
RV-9A N323TP
 
Ironflight said:
So – if you find yourself with worn out exhaust hanger ends like I did, don’t despair – Larry has replacements – and you can make a temporary with a trip to your Ace Hardware and Aviation Supply Store. They’re likely to give you six inches of the stuff – don’t bother with Home Depot – they only want to sell a 20’ coil!

Paul
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I keep a length of steel brake line from the aviation aisle of the local AutoZone in the shop (and a short piece in the flight bag) for making new hangers. You can buy whatever length you need at any auto parts store.

Think I got this idea from Larry Vetterman many years ago.
 
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I have some 3/8" OD x .035" wall 4130 tube at the hangar. I will make some spares from that. Will let you know in 5-10 years if they hold up :)
 
I used to suffer from broken exhaust hangars until I solved the problem by fabricating an 1/4" aluminum strap that goes between the two pipes. Doing so will connect the pipes solidly but will still allowed movement for expansion and vibration. Haven't had a problem in over 1000 hours since.
 
Sam Buchanan said:
I keep a length of steel brake line from the aviation aisle of the local AutoZone in the shop (and a short piece in the flight bag) for making new hangers. You can buy whatever length you need at any auto parts store.

Think I got this idea from Larry Vetterman many years ago.
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Just wanted to update this thread for those who have checked every auto parts or home improvement store in their area ( like me) NO JOY

However, my local Ace hardware is now stocking 12" sections of 3/8" .028 stainless steel tubing for $6.
 
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GLPalinkas said:
Just wanted to update this thread for those who have checked every auto parts or home improvement store in their area ( like me) NO JOY

However, my local Ace hardware is now stocking 12" sections of 3/8" .028 stainless steel tubing for $6.
Click to expand...

Your saying your auto parts store doesn't stock brake lines????

Every parts store I've been in has steel brake lines in several lengths. Buy whatever length you need, cut off the ends so the fittings can be slid off the tubing and you have enough stock to make several exhaust hangers.

Here is a 72" line from Advance Auto for less than 8 bucks:

http://shop.advanceautoparts.com/we...90070-p?searchTerm=brake+lines&zoneAssigned=1

22190070_ags_pa672_pri_mini.jpg
 
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i made some replacement parts from solid steel stock about 10 years ago. smashed the ends flat enough to drill out the wholes. i dought they will ever wear out. i little more work but a solid repair. :)
 
Spruce has 3/8" 304 stainless tubing too.

Welded, .028 walls is $6.75/ft
Seamless, .035 walls is $3.20/ft

Next time I make a 'spruce order, I probably should grab a foot of this tubing just to keep on hand for when one of my exhaust hangars breaks. Probably wouldn't be a bad idea to make up one replacement segment to toss into the travel toolbag as well since there are at least 4 pieces of this stuff on the exhaust of my -6.
 
Sam Buchanan said:
Your saying your auto parts store doesn't stock brake lines????

Every parts store I've been in has steel brake lines in several lengths. Buy whatever length you need, cut off the ends so the fittings can be slid off the tubing and you have enough stock to make several exhaust hangers.

Here is a 72" line from Advance Auto for less than 8 bucks:

http://shop.advanceautoparts.com/we...90070-p?searchTerm=brake+lines&zoneAssigned=1

22190070_ags_pa672_pri_mini.jpg
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Sam, you must have missed the "stainless" part of the equation that the OP Paul talked about. I found lots of steel brake lines at those places but no one carries the stainless steel variety. My exhaust is circa 1998 and the hangers were some sort of softer tubing. I have had them break three times in 160 hours. Thought I would use stainless steel like Larry now sends out with the newer exhausts. I found what I needed at Ace Hardware and wanted to help others searching for same. Gary
 
GLPalinkas said:
Sam, you must have missed the "stainless" part of the equation that the OP Paul talked about. I found lots of steel brake lines at those places but no one carries the stainless steel variety. My exhaust is circa 1998 and the hangers were some sort of softer tubing. I have had them break three times in 160 hours. Thought I would use stainless steel like Larry now sends out with the newer exhausts. I found what I needed at Ace Hardware and wanted to help others searching for same. Gary
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As a general rule stainless is not one of the harder steels. The steel brake lines have worked well on the 1999 vintage exhaust on my -6. I found the key to reducing breaking is making sure the mounts weren't trying to flex where they are attached and also being careful not to kink the tubing where it is flattened. I've had two or three to break over the course of 1200 hrs but replacement is easy.

Hope the stainless works well for you. Just be advised there are many different flavors of stainless, some harder than others. I would consider 4130 steel an upgrade if you want something robust.
 
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Style

Seems like a good thread to revive, since there are pictures. I like pictures.

I am lately having all sorts of breakage issues. I have a Vetterman 4x4 on my
0-360 RV 6.

Mine mounts to the engine mount instead of the engine sump. The Adel clamps are breaking on me, the rubber hose pieces are cracking, and the top hangar strap broke also.

I used some inferior hose last week and had to replace that with the right stuff while on the ramp during the HII FFI clinic. I still had some minor shaking issues during the weekend and by the time I got home Sunday the shaking had returned to its full glory. I suspect that when I take the cowl off today I will find loose and/or broken exhaust bits a'plenty.

I am wondering if the recent rash of problems could actually be caused from something down line going on, maybe there is a reason not directly related to the exhaust mounting style per se.

I didn't have any exh hgr problems for the first 2-300 hours I have had this a/c, but now they seem to be a more regular occurrence. I admit freely that my formation flying and it's associated learning curve (ham fisted throttle at times) is probably part of the deal....but hey!

So my question is, how can I make a better exh hgr system to accommodate my cough, cough, flying style?
 
Balance

Cathy,
Have you had the prop balanced? I'm wondering if some of the vib may be originating there. Also, any idea when the mounts were installed/replaced?
My thoughts are that you may have some other things going on that may be adding to the vibration issues with the exhaust.
cj
 
grubbat said:
Cathy,
Have you had the prop balanced? I'm wondering if some of the vib may be originating there. Also, any idea when the mounts were installed/replaced?
My thoughts are that you may have some other things going on that may be adding to the vibration issues with the exhaust.
cj
Click to expand...

I am going to get the prop balanced however I suspect that since there is no vibration when I first rebuild the hangars, the prop may not be involved. Regardless, it is going to get balanced. One thing eliminated from the equation.
 
4 pipe on RV-4

I have the 4 pipe Vetterman on my-4. I used 3/8" diameter stainless tubing with hiem rod ends (similar to the aileron pushrods) that run from the back of the sump(engine sump attach bolts) down to the pipe gang clamps that come with the exhaust. I made a steel angle for the sump end, and at the clamp end with a hole for the rod end to bolt to. The system is very rigid, yet completely moveable(if that makes any sense). Because it is not connected to the airframe which is fixed, there is no transfer of load to cause fatigue. 250 hrs. so far, and I do lots of light acro and formation so it gets plenty of rapid throttle changes...no cracks or problems.
 
Hangar on

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A couple of weeks ago I made this bracket. Last weekend it broke, in the same place, in the same way as the previous one.

While I was looking for ideas I swung the prop blade and looked at the track. One blade was about 1/4". So I begrudgingly cut all that great safety wire on the prop bolts in hopes that a re-tourque might line up the blades better.

I'll be looking for more expertise on this before out all goes back together but would the track cause any issues with my exhaust that were not present before I took the prop off in Dec?
 
Quick reminder; reduction of cooling drag requires increasing the lower cowl exit velocity. Hanging a bunch of hardware in the exit, in particular fat, round tube shapes, clamps, and chunk aluminum, is counterproductive.

Cable hangers are less draggy, and seem to be bulletproof. This one was supplied by AWI, but there are endless variations:



Even if you don't care about drag reduction, there are many other ways to hang a tailpipe. For example, this is the tailpipe hanger for a Maule...fatigue is not an issue:



This is a standard automotive tailpipe hanger. Obviously durable; when is the last time you saw a dragging tailpipe? Think you can work it into a good design?



Set your mind free. Stop designing bandaids.
 
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