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Did header wrap today


procharger

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What brand did you get? used a lot of it over the years and it seems the cheaper stuff sheds the fiberglass worse.. not fun when you get that crap all over your arms etc. I'm starting to itch just thinking about it. And the cheap stuff doesn't hold up as well... I use it alot (have it on my homebuilt headers on my plane etc.)

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As mentioned in the approval Corey posted, the wrap reduces visibility to exhaust pipe problems.  That's the only thing that keeps me from doing it, since I've already had failed welds on both an exhaust pipe and the muffler.  I'd like to have the reduced temps under the cowl, but I really feel like I need to keep a close eye on my exhaust pipes.

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Any 2" header wrap cloth from an auto parts store will work. Some are painted black and some are plane. I prefer plain to work with. The reason for the name in the LOA is that was the first one I used.

 

"As mentioned in the approval Corey posted, the wrap reduces visibility to exhaust pipe problems."  

 

This is a misnomer from people who have never used this wrap for many years.

Hi Andy,

 

Of all people I would think you would know better. What happened to your exhaust pipe? Post your broken exhaust pipe pictures. Do you think header wrap would have hidden that. Pipes don't get a tiny crack. They snap all the way across and break. You don't get hidden issues that you can't see. I have been using header wrap on Rotax engines for more than 15 years and see lots of engines come in with it. It has never caused an issue or hid anything visible. Even if a pipe crack the exhaust blowby alone would tear the wrap and leave blowby exhaust gas debris all over that area.

 

When a pipe breaks you can hear it many times in the cockpit.

post-3-0-10489600-1459259642_thumb.jpg

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Hi Andy,

 

Of all people I would think you would know better. What happened to your exhaust pipe? Post your broken exhaust pipe pictures. Do you think header wrap would have hidden that. Pipes don't get a tiny crack. They snap all the way across and break. You don't get hidden issues that you can't see. I have been using header wrap on Rotax engines for more than 15 years and see lots of engines come in with it. It has never caused an issue or hid anything visible. Even if a pipe crack the exhaust blowby alone would tear the wrap and leave blowby exhaust gas debris all over that area.

 

When a pipe breaks you can hear it many times in the cockpit.

 

Thanks Roger, sorry I don't know any better...I'm a slow learner.     :giggle-3307:  

 

I assume that all breaks start with stress cracks, like the ones I had in my muffler.  My assumption is that the broken weld I experienced was the result of a stress crack that I just didn't see until it was a full break.  

 

Now, it's certainly possible that even a small crack is going to leak enough gas to blow out a small area of the wrap and reveal itself that way.  I just don't have enough experience to know.   

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When your exhaust pipe starts the crack it is quick and swift. It doesn't happen over time. It is because of side load stresses and poor weld reliefs. When it starts it snaps. In all my years with a stainless Rotax exhaust pipe I have never seen just a tiny crack. 

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When your exhaust pipe starts the crack it is quick and swift. It doesn't happen over time. It is because of side load stresses and poor weld reliefs. When it starts it snaps. In all my years with a stainless Rotax exhaust pipe I have never seen just a tiny crack. 

 

Cool, thanks.  That is the experience I had, as you know.  I'll start planning to wrap my pipes, maybe it will extend the life of my old-style ignition modules...

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Unless there's something special about ROTAX exhausts, aircraft exhaust DO sometimes show signs of impending failure with tiny leaks/cracks before failure.

 

Googled image from a Mooney:

 

2015122495105323.jpg.d77f7081cc9e36a548c

 

I think the fear that exhaust wrap could hide an imminent problem is warranted. The MOST Conservative Action would be to remove/replace the wrap at every inspection. Or just cast a very careful eye at the wrap itself for any sign of exhaust leakage.

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When you buy a header wrap: avoid the ones that require the silicone spray. I used DEI's titanium wrap (it's actually fiberglass).

 

Also, cracks in exhausts can be caused by two things: unbalanced prop, and poor lubrication of the knuckle joints causing them to seize. They should be lubricated regularly, but the rotax manuals don't exactly specify a time period, only that they echo these words. I've made it a habit to use NICKEL anti-seize every couple hundred hours. I know copper was recommended previously, but upon further research, copper causes stainless steel embrittlement over time due to amalgamation and we've had a lot of problems with ball joints cracking and decaying when using copper (copper anti-seize is prohibited in nuclear power plants due to this problem).

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They should be lubricated regularly, but the rotax manuals don't exactly specify a time period, only that they echo these words. I've made it a habit to use NICKEL anti-seize every couple hundred hours.

Coincidentally, my Sky Arrow calls for every 200 hours.

 

FWIW, 2 are straightforward. Two are fiendishly hard.

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http://www.permatex.com/products-2/product-categories/lubricants/specialty-lubricants-anti-seize/permatex--nickel-anti-seize-lubricant-detail

 

It's like a grease. You can get them from auto parts stores, but they often have to be shipped from a warehouse. Get it before you start mucking with the exhaust.

 

The nickel stays around longer than copper too.

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Hi Eddie,

 

That's a Mooney and that exhaust pipe is steel. See the rust not to mention the poor welding. Stainless is more brittle.

 

Looks like a regular stainless aircraft exhaust to me. Stainless exhaust don't always stay looking nice and perfect their whole lives.

 

Speaking of stainless aircraft exhaust, I have a new muffler ordered for my Piper Warrior. Where the exhaust enters the muffler the tube is cracked all the way around. This seems to be a common problem, so I teach my students to check for it on their pre flight inspections. It was a student that caught this crack. The bad thing is they went flying before they told me about it.

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One negative on the Sky Arrow is the difficulty in uncowling it. Not a huge deal, but ladders are involved, and getting it back on requires some judicious jiggling - not something you'd want to do daily.

 

Loved my Grummans in that regard - it would be nice if all planes were that easy to open up and check.

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In my experience, exposed exhaust will burn through the wrap pretty easily showing you the problem (and letting you hear it, if hearing it is a possibility over other noises of flying/driving/exhaust etc.) I probably couldn't hear a leak over my 4-1 straight piped exhaust on my 912 so I pull the cowl quite often (for other inspection reasons, and constant tweaking and modifying stuff as well) and check everything over to make sure... I wasn't real impressed with the stainless pipe I used when building these headers so I've been a little nervous (claimed as 304, I don't think it is). I made small heat shields between the headers and carbs/oil lines etc. just in case something cracks it won't be spitting fire onto those items  :lol:  But the exhaust wrap is nice to have, the quality stuff will allow you to place your hand on the pipes surprisingly quickly after running and engine - (even running one hard) do this at your own risk of course  B)

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