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Exhaust spring wear

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Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Wed May 18, 2011 5:40 am Post subject: Exhaust spring wear

Hi All,



While I was doing another rubber hose replacement on a relatively higher time plane I noticed the springs are worn almost half way through where they connect over the loop on the exhaust pipe and muffler. I have seen this many times before and had forgot to mention something before. They do not need to be worn all the way through before they just break off and you will never know when it will fail. I used to own a Kolb MK III  a long time ago and one did break before I caught it at 800 hrs. All the Rotax 912's have spring wear. When your plane gets to approximately 800 hrs. you need to toss the 8 exhaust springs and replace them. The vibration can and will eat right through the spring hook. You don't have to take anything else off, just pull the springs. Safety wire them and then re-apply the high temp silicone on the spring. There are two ways to apply silicone. The first way is to actually fill the inside of the spring with silicone. The second way and the one I use is to apply the silicone on the outside of the spring from top to bottom. Make it at least 3/8" wide and 1/4" tall. You need to give it some strength anbody by making it wide and tall enough to work. I thin little bead is worthless. Work it in between the spring coils. This is to dampen the vibration to the spring and help prevent premature spring breakage and help with the wear I just mentioned above.



I have 720 hrs on my plane and they are worn half way through on 3 springs and a quarter the way through on the others. 



p.s.

You can have faster exhaust spring wear so these should always be checked as the engine builds time, but I usually see the problem right around 700-800 hrs. Just keep an eye on yours.

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_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

pchristensen10(at)austin.
Guest

Posted: Wed May 18, 2011 5:59 am Post subject: Exhaust spring wear

I replaced my springs last summer because they were worn quite a bit     nearly 1/2 through (maybe 580 hours).  I had one of the new         springs break on my tripthis year to Sun N Fun.  I     had the silicon and safety wire on the springs so they held until I     noticed the broken spring immediately upon arriving home.  I'm     guessing that I damaged the spring with my vice grips when I     installed it. Probably gouged the spring (or the tornado did it.     ;>)

     

     Pete

     Kitfox III , (early 912 going on 650 hours)

     

     On 5/18/2011 8:40 AM, Roger Lee wrote:     [quote]        	  Quote: 	
		  --> RotaxEngines-List message posted by: "Roger Lee" <ssadiver1(at)yahoo.com> (ssadiver1(at)yahoo.com)



Hi All,



While I was doing another rubber hose replacement on a relatively higher time plane I noticed the springs are worn almost half way through where they connect over the loop on the exhaust pipe and muffler. I have seen this many times before and had forgot to mention something before. They do not need to be worn all the way through before they just break off and you will never know when it will fail. I used to own a Kolb MK III  a long time ago and one did break before I caught it at 800 hrs. All the Rotax 912's have spring wear. When your plane gets to approximately 800 hrs. you need to toss the 8 exhaust springs and replace them. The vibration can and will eat right through the spring hook. You don't have to take anything else off, just pull the springs. Safety wire them and then re-apply the high temp silicone on the spring. There are two ways to apply silicone. The first way is to actually fill the inside of the spring with silicone. The second way and the one I use is to 

 

!

 apply the silicone on the outside of the spring from top to bottom. Make it at least 3/8" wide and 1/4" tall. You need to give it some strength anbody by making it wide and tall enough to work. I thin little bead is worthless. Work it in between the spring coils. This is to dampen the vibration to the spring and help prevent premature spring breakage and help with the wear I just mentioned above.



I have 720 hrs on my plane and they are worn half way through on 3 springs and a quarter the way through on the others. 



p.s.

You can have faster exhaust spring wear so these should always be checked as the engine builds time, but I usually see the problem right around 700-800 hrs. Just keep an eye on yours.



--------

Roger Lee

Tucson, Az.

Light Sport Repairman - Maintenance Rated

Rotax Repair Center

Home 520-574-1080  TRY HOME FIRST

Cell 520-349-7056





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=340277#340277



	
     [b]

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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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Arty Trost

Joined: 25 May 2006
Posts: 205
Location: Sandy, Oregon

Posted: Wed May 18, 2011 6:06 am Post subject: Exhaust spring wear

Hi Roger -



My springs don't last anywhere near as long - usually about 150 hrs, even with high temp silicone. Even though I keep my Drifter hangared, the springs rust. I think it's because we're on the rainy side of the Oregon Cascades, with lots of humidity. Checking them is part of my pre-flight, and I change them at every annual.



Arty Trost

Maxair Drifter

Sandy, Oregon



www.LessonsFromTheEdge.com/uladventure2009.htm

 

 

--- On Wed, 5/18/11, Roger Lee <ssadiver1(at)yahoo.com> wrote:

[quote]Hi All,



While I was doing another rubber hose replacement on a relatively higher time plane I noticed the springs are worn almost half way through where they connect over the loop on the exhaust pipe and muffler. I have seen this many times before and had forgot to mention something before. They do not need to be worn all the way through before they just break off and you will never know when it will fail. I used to own a Kolb MK III  a long time ago and one did break before I caught it at 800 hrs. All the Rotax 912's have spring wear. When your plane gets to approximately 800 hrs. you need to toss the 8 exhaust springs and replace them. The vibration can and will eat right through the spring hook. You don't have to take anything else  off, just pull the springs. Safety wire them and then re-apply the high temp silicone on the spring. There are two ways to apply silicone. The first way is to actually fill the inside of the spring with silicone. The second way and the one I use is to !

 apply the silicone on the outside of the spring from top to bottom. Make it at least 3/8" wide and 1/4" tall. You need to give it some strength anbody by making it wide and tall enough to work. I thin little bead is worthless. Work it in between the spring coils. This is to dampen the vibration to the spring and help prevent premature spring breakage and help with the wear I just mentioned above.



I have 720 hrs on my plane and they are worn half way through on 3 springs and a quarter the way through on the others. 



p.s.

You can have faster exhaust spring wear so these should always be checked as the engine builds time, but I usually see the problem right around 700-800 hrs. Just keep  an eye on yours.



--------

Roger Lee

Tucson, Az.

Light Sport Repairman - Maintenance Rated

Rotax Repair Center

Home 520-574-1080  TRY HOME FIRST

Cell 520-349-7056





Read this topic online here:



http://forums.matronics.com/viewtopicf="http://www.matronics.com/Navigator?RotaxEngines-List"  target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List  -->  [quote][b]

- The Matronics RotaxEngines-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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bob(at)fly-ul.com
Guest

Posted: Wed May 18, 2011 7:07 am Post subject: Exhaust spring wear

RE Spring breakage...



I wonder if these springs would be any better than the Rotax springs: http://jbmindustries.com/ROTAX.htm



Their two-stroke carb/plug boots, are WAY better than the crappy Rotax boots.

--

Bob Comperini

e-mail: bob(at)fly-ul.com

WWW: http://www.fly-ul.com

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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Thu May 19, 2011 6:14 am Post subject: Re: Exhaust spring wear

I am familiar with those other springs and they are fine. Some of you have some excessive spring wear at 150 hrs. Thats lots of vibration pulsation going on or just poor quality springs.



I guess the bottom line here is forget the hour time check or replacement on the springs and keep an extra good eye on them all the time. Make sure they are safety wired and silicone will definitely help this wear. Just a note on the silicone. From some of the planes that come in to my shop it is evident that many owners do not use a big enough bead down the spring or work it into the coils. The silicone must have enough mass to do you some good. A thin bead won't cut it.

- The Matronics RotaxEngines-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

cscsail(at)gmavt.net
Guest

Posted: Thu May 19, 2011 7:29 am Post subject: Exhaust spring wear

200+ hrs, no silicone and no signs of wear. Wondering if the silicone 

prevents the springs from holding with enough force to keep them in place. I 

also have so little vibration that I would not expect the springs to be and 

issue, but checked yesterday after reading the post.

Gordon



---

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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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pchristensen10(at)austin.
Guest

Posted: Sun May 22, 2011 12:37 pm Post subject: Exhaust spring wear

I just had another spring fail.  Less than a year old.  I suspect they 

got a batch from China.



Pete

On 5/19/2011 9:14 AM, Roger Lee wrote:

 	  Quote: 	
		   



 I am familiar with those other springs and they are fine. Some of you have some excessive spring wear at 150 hrs. Thats lots of vibration pulsation going on or just poor quality springs.



 I guess the bottom line here is forget the hour time check or replacement on the springs and keep an extra good eye on them all the time. Make sure they are safety wired and silicone will definitely help this wear. Just a note on the silicone. From some of the planes that come in to my shop it is evident that many owners do not use a big enough bead down the spring or work it into the coils. The silicone must have enough mass to do you some good. A thin bead won't cut it.



 --------

 Roger Lee

 Tucson, Az.

 Light Sport Repairman - Maintenance Rated

 Rotax Repair Center

 Home 520-574-1080  TRY HOME FIRST

 Cell 520-349-7056





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=340390#340390

- The Matronics RotaxEngines-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?RotaxEngines-List

grahamsingleton(at)btinte
Guest

Posted: Sun May 22, 2011 2:37 pm Post subject: Exhaust spring wear

I've seen some springs that have failed. The tabs on the exhaust were not properly de burred and had cut through the springs. So, check the holes in the tabs for sharp edges.

Graham

From: Pete Christensen <pchristensen10(at)austin.rr.com>

To: rotaxengines-list(at)matronics.com

Sent: Sunday, 22 May, 2011 21:34:56

Subject: Re: RotaxEngines-List: Re: Exhaust spring wear

--> RotaxEngines-List message  posted by: Pete Christensen <pchristensen10(at)austin.rr.com (pchristensen10(at)austin.rr.com)>

I just had another spring fail.  Less than a year old.  I suspect they 

got a batch from China.

Pete

On 5/19/2011 9:14 AM, Roger Lee wrote:

 	  Quote: 	
		   -->  RotaxEngines-List message posted by: "Roger Lee"<ssadiver1(at)yahoo.com (ssadiver1(at)yahoo.com)>

 I am familiar with those other springs and they are fine. Some of you have some excessive spring wear at 150 hrs. Thats lots of vibration pulsation going on or just poor quality springs.

 I guess the bottom line here is forget the hour time check or replacement on the springs and keep an extra good eye on them all the time. Make sure they are safety wired and silicone will definitely help this wear. Just a note on the  silicone. From some of the planes that come in to my shop it is evident that many owners do not use a big enough bead down the spring or work it into the coils. The silicone must have enough mass to do you some good. A thin bead won't cut it.

 --------

 Roger Lee

 Tucson, Az.

 Light Sport Repairman - Maintenance Rated

 Rotax Repair Center

 Home 520-574-1080  TRY HOME FIRST

 Cell 520-349-7056

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=340390#340390

&ghref="http://www.matronics.com/Navigator?RotaxEngines-List" target="_bl-========================tp://forums.matronics.com" target="_blank">http://forums.matronics.comhttp

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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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