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Cracked Eng Mount

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ppeerenbo(at)charter.net
Guest

Posted: Thu Jun 01, 2006 3:27 am Post subject: Cracked Eng Mount

I have a Model IV with a 912UL 360TT. I found a eng mount crack on the short 

tube that connects the top mounts, left side. The crack looked like a stain 

on the powered coated mount that wiped off. I cleaned the paint off and the 

tube is cracked half way around. Can any one give me information on the 

mount? Wall thickness, any weld repair advice is welcome.



Paul N102DG

Jim Shumaker

Joined: 09 Jan 2006
Posts: 106

Posted: Thu Jun 01, 2006 5:11 am Post subject: Cracked Eng Mount

Paul

   

  I just found a crack on my model III 912ul.  It was on the top of the ring tube of the dynafocal mount.  When I pulled the engine, one of the short tubes was also cracked.  I have not even done a complete inspection yet.  Will keep you informed as to what I find.  

   

  Even with two cracked tubes on the mounts the engine felt tight and secure on the frame.  

   

  Jim Shumaker



Paul <ppeerenbo(at)charter.net> wrote:

  



I have a Model IV with a 912UL 360TT. I found a eng mount crack on the short 

tube that connects the top mounts, left side. The crack looked like a stain 

on the powered coated mount that wiped off. I cleaned the paint off and the 

tube is cracked half way around. Can any one give me information on the 

mount? Wall thickness, any weld repair advice is welcome.



Paul N102DG

_________________
Jim Shumaker

jimmieblackwell(at)sbcglo
Guest

Posted: Thu Jun 01, 2006 7:24 am Post subject: Cracked Eng Mount

This the third engine mount problem, (including mine), with the 912 UL in the last two weeks.  I wanted to ask Jim and Paul to post a picture of their cracked mounts on Sportflight and let's try to determine if there is are some common denominators such as torque or total hours on the mount when it fails.  Looks like Paul and I had about the same amount of hours when the failure occurred.

   

   My rubber engine mount pads had been changed within 15 hours of when my engine mount broke.  When changing the rubber pads I torgued all the hardware according to the latest Model IV building manual.  I can't help but wonder if the torque settings may be wrong or if there was a batch of bad engine mounts produced at some point.  Hopefully, some of you with more experience and knowledge can help us figure out what is causing the engine mount failures before someone hurts their Kitfox or worse, themselves.

   

  Jimmie

James Shumaker <jimshumaker(at)sbcglobal.net> wrote: 

  



Paul



I just found a crack on my model III 912ul. It was on the top of the ring tube of the dynafocal mount. When I pulled the engine, one of the short tubes was also cracked. I have not even done a complete inspection yet. Will keep you informed as to what I find. 



Even with two cracked tubes on the mounts the engine felt tight and secure on the frame. 



Jim Shumaker



Paul 

wrote:




I have a Model IV with a 912UL 360TT. I found a eng mount crack on the short 

tube that connects the top mounts, left side. The crack looked like a stain 

on the powered coated mount that wiped off. I cleaned the paint off and the 

tube is cracked half way around. Can any one give me information on the 

mount? Wall thickness, any weld repair advice is welcome.



Paul N102DG

smokey_bear_40220(at)yaho
Guest

Posted: Thu Jun 01, 2006 7:58 am Post subject: Cracked Eng Mount

Jimmie and all,



I do not have the 912, but wonder after reading other

posts on this list if it isn`t a problem with start

and shutdown shaking from the high compression. 

Unless you have inflight vibration that occurs at rpms

you should stay away from, it would seem the biggest

vibration is durning starting and stopping.  Different

props would likely mean different running vibrations,

so unless your props are the same, that should not be

the problem.



Do you have clutches installed?



How much does the plane shake when you start?



Do you notice inflight vibs?



Have you had exhaust cracks that would indicate

running vibs?



Carbs falling off?



These questions have been raised before on the list

and there may be a connection.



Kurt S.  S-5/NSI turbo



--- Jimmie Blackwell <jimmieblackwell(at)sbcglobal.net>

wrote:



 	  Quote: 	
		   This the third engine mount problem, (including

 mine), with the 912 UL in the last two weeks.


	


__________________________________________________

ppeerenbo(at)charter.net
Guest

Posted: Thu Jun 01, 2006 3:01 pm Post subject: Cracked Eng Mount

I will take a picture this weekend. I have had a carb come off 200  plus hrs 

ago, balancing carbs, new carb sockets, and spring kit seams to have taken 

care of that. 100 plus hrs ago I did the mod to stiffen the eng mounts 

(shorten the bushings). Its more than likely that this has been cracked for 

a wile. Its appears to emanate from the weld and I would say it went aft 

first and could go unnoticed easily. I am an airline mechanic for 27 years, 

including time as a level II NDT, PT, UT, ET & PM. If I had just wiped the 

stain and not go further with power coat removal, it would go till the next 

annual inspection, this is a very fine tight crack. I do not have a slipper 

clutch, and the 912 does shake if you don't get a clean start. The start 

procedure that was on this list of using choke with the ignition off and let 

sit, then set the throttle seams to work better than the primer system. ( I 

took that off) I have never had exhaust or any real fretting problems, when 

running the 912 is awsom powerplant.



Paul N102DG

---

mike
Guest

Posted: Thu Jun 01, 2006 4:43 pm Post subject: Re: Cracked Eng Mount

another thing to be concerned about is shut down.  What I do is run the rpm's up to about 3000 and then turn off the mags and pull back on the throttle as far as it will go at the same time.

Jim Shumaker

Joined: 09 Jan 2006
Posts: 106

Posted: Thu Jun 01, 2006 9:51 pm Post subject: Cracked Eng Mount

I'll try to get pictures up this weekend also.  

   

  My guess is that it is the shaking of the engine.  There is not any distortion associated with the cracks on my engine and they are not cracked all the way around.  

   

  Jim Shumaker



Paul <ppeerenbo(at)charter.net> wrote:

  

I will take a picture this weekend. I have had a carb come off 200 plus hrs 

ago, balancing carbs, new carb sockets, and spring kit seams to have taken 

care of that. 100 plus hrs ago I did the mod to stiffen the eng mounts 

(shorten the bushings). Its more than likely that this has been cracked for 

a wile. Its appears to emanate from the weld and I would say it went aft 

first and could go unnoticed easily. I am an airline mechanic for 27 years, 

including time as a level II NDT, PT, UT, ET & PM. If I had just wiped the 

stain and not go further with power coat removal, it would go till the next 

annual inspection, this is a very fine tight crack. I do not have a slipper 

clutch, and the 912 does shake if you don't get a clean start. The start 

procedure that was on this list of using choke with the ignition off and let 

sit, then set the throttle seams to work better than the primer system. ( I 

took that off) I have never had exhaust or any real fretting problems, when 

running the 912 is awsom powerplant.



Paul N102DG

---

_________________
Jim Shumaker

gjglh(at)cebridge.net
Guest

Posted: Fri Jun 02, 2006 5:38 pm Post subject: Cracked Eng Mount

I had to pull my engine because of a cracked motor mount. Facing the engine the top 

left verticle downward tube broke of 3/4" above rubber mounts and the right side of 

the cross tube for the upper mounts had a crack 1/2" in. I put an outer tube layer 

on each tube to give added strength.

Gary

M-IV Speedster



On Fri Jun  2  1:48 , James Shumaker <jimshumaker(at)sbcglobal.net> sent:



 	  Quote: 	
		  



I'll try to get pictures up this weekend also.  

   

  My guess is that it is the shaking of the engine.  There is not any distortion 

associated with the cracks on my engine and they are not cracked all the way 
	


around.  

[quote]   

  Jim Shumaker



Paul ppeerenbo(at)charter.net> wrote:

  

I will take a picture this weekend. I have had a carb come off 200 plus hrs 

ago, balancing carbs, new carb sockets, and spring kit seams to have taken 

care of that. 100 plus hrs ago I did the mod to stiffen the eng mounts 

(shorten the bushings). Its more than likely that this has been cracked for 

a wile. Its appears to emanate from the weld and I would say it went aft 

first and could go unnoticed easily. I am an airline mechanic for 27 years, 

including time as a level II NDT, PT, UT, ET & PM. If I had just wiped the 

stain and not go further with power coat removal, it would go till the next 

annual inspection, this is a very fine tight crack. I do not have a slipper 

clutch, and the 912 does shake if you don't get a clean start. The start 

procedure that was on this list of using choke with the ignition off and let 

sit, then set the throttle seams to work better than the primer system. ( I 

took that off) I have never had exhaust or any real fretting problems, when 

running the 912 is awsom powerplant.



Paul N102DG

---

Jim Shumaker

Joined: 09 Jan 2006
Posts: 106

Posted: Sat Jun 03, 2006 6:16 am Post subject: Cracked Eng Mount

The cracks on my mounts seem to be in the same places.

   

  Jim Shumaker



gjglh(at)cebridge.net wrote:

  



I had to pull my engine because of a cracked motor mount. Facing the engine the top 

left verticle downward tube broke of 3/4" above rubber mounts and the right side of 

the cross tube for the upper mounts had a crack 1/2" in. I put an outer tube layer 

on each tube to give added strength.

Gary

M-IV Speedster



On Fri Jun 2 1:48 , James Shumaker sent:



 	  Quote: 	
		  



I'll try to get pictures up this weekend also. 

 

 My guess is that it is the shaking of the engine. There is not any distortion 

associated with the cracks on my engine and they are not cracked all the way 
	


around. 

[quote] 

 Jim Shumaker



Paul ppeerenbo(at)charter.net> wrote:

 

I will take a picture this weekend. I have had a carb come off 200 plus hrs 

ago, balancing carbs, new carb sockets, and spring kit seams to have taken 

care of that. 100 plus hrs ago I did the mod to stiffen the eng mounts 

(shorten the bushings). Its more than likely that this has been cracked for 

a wile. Its appears to emanate from the weld and I would say it went aft 

first and could go unnoticed easily. I am an airline mechanic for 27 years, 

including time as a level II NDT, PT, UT, ET & PM. If I had just wiped the 

stain and not go further with power coat removal, it would go till the next 

annual inspection, this is a very fine tight crack. I do not have a slipper 

clutch, and the 912 does shake if you don't get a clean start. The start 

procedure that was on this list of using choke with the ignition off and let 

sit, then set the throttle seams to work better than the primer system. ( I 

took that off) I have never had exhaust or any real fretting problems, when 

running the 912 is awsom powerplant.



Paul N102DG

---

_________________
Jim Shumaker

pwmac(at)sisna.com
Guest

Posted: Tue Jun 06, 2006 3:10 pm Post subject: Cracked Eng Mount

There are many examples of cracked mounts before Skystar came up with 

the heavy wall mount $$. Most of the cracks were in the tubing - not 

even close to the welds. Guys with powder coated mounts found the 

cracks were hidden by the coating because the coating is so flexible. 

I would strongly recommend removing the coating on all the upper 

tubes from weld to weld and making a close examination. When the 

repair is complete don't powder coat use and enamel paint which is 

brittle and will reveal a crack as soon as it happens. White is the 

best color for showing cracks.`



BTW, there are several reports of the Skystar repairs failing again, 

but fix I used is much better than the temporary fix that Skystar was 

using and did not work.



If you want the details on how to do a DIY beefup/repair let me know 

and I will PM you with pics and specs which Frank Miller gave me. 

This info is applicable for the M4 mount which was a Skystar design. 

If the newer models use the Rotax style with the circular /ring mount 

then I would be of no help.

I hesitate to post the long winded message on the list so If someone 

else wants the info I will send it to them as well.



Avoid cracks by using a protocol for start and shutdown that 

eliminates engine shake, but, that is another thread.

Regards, Paul W

===============



At 04:58 PM 6/1/2006, you wrote:

[quote]



I will take a picture this weekend. I have had a carb come off 200  plus hrs

ago, balancing carbs, new carb sockets, and spring kit seams to have taken

care of that. 100 plus hrs ago I did the mod to stiffen the eng mounts

(shorten the bushings). Its more than likely that this has been cracked for

a wile. Its appears to emanate from the weld and I would say it went aft

first and could go unnoticed easily. I am an airline mechanic for 27 years,

including time as a level II NDT, PT, UT, ET & PM. If I had just wiped the

stain and not go further with power coat removal, it would go till the next

annual inspection, this is a very fine tight crack. I do not have a slipper

clutch, and the 912 does shake if you don't get a clean start. The start

procedure that was on this list of using choke with the ignition off and let

sit, then set the throttle seams to work better than the primer system. ( I

took that off) I have never had exhaust or any real fretting problems, when

running the 912 is awsom powerplant.



Paul N102DG

---

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