Broken Exhaust Hanger ? and a Temporary Fix

[Ironflight]

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.



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!?





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

[Lars]

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.

[kevinh]

Originally Posted by Lars

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.

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.

[Ironflight]

Originally Posted by kevinh

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.

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....

[terrykohler]

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

[Sam Buchanan]

Originally Posted by Ironflight

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

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.

[Lars]

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

[rocketbob]

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.

[GLPalinkas]

Originally Posted by Sam Buchanan

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.

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.

[TS Flightlines]

Everyone--
online metals.com has 3/8, .028 , 304 stainless for $3.78/ foot
Tom