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		tiger862(at)ligtel.com Guest
 
 
 
 
 
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				 Posted: Mon Sep 18, 2006 8:39 am    Post subject: lower cowling | 
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				Is there anyway to repair cracks in a lower cowling  on a 1978 Tiger, besides putting patches on the  outside?
     [quote][b]
 
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		flyv35b(at)minetfiber.com Guest
 
 
 
 
 
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				 Posted: Mon Sep 18, 2006 9:28 am    Post subject: lower cowling | 
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				Yes, put the patch on the INSIDE and flush rivet  it.  The patch and cowl skin can usually be dimpled to accept the flush  rivet.  Use AN426-3 rivets typically.
   
  Cliff  A&P/IA
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		GrummanDude
 
 
  Joined: 15 Jan 2006 Posts: 926 Location: Auburn, CA
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				 Posted: Mon Sep 18, 2006 11:20 am    Post subject: lower cowling | 
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				Unfortunately, no.  You're stuck with a patch.  All 78 and 79 Tiger 
 cowlings will crack on the lower right side in the cooling exit ramp 
 area.  The metal cooling exit ramps do not absorb enough of the 
 vibrations from the prop-exhaust pulses.  The only way I know of to 
 recuce or eliminate future cracks is to replace the metal ramp with a 
 fiberglass ramp.
 
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  _________________ Gary
 
AuCountry Aviation
 
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		az_gila
 
 
  Joined: 17 Jun 2006 Posts: 99 Location: Tucson, AZ
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				 Posted: Mon Sep 18, 2006 9:19 pm    Post subject: lower cowling | 
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				At 12:19 PM 9/18/2006, you wrote:
   	  | Quote: | 	 		  --> TeamGrumman-List message posted by: teamgrumman(at)aol.com
 
  Unfortunately, no.  You're stuck with a patch.  All 78 and 79 Tiger cowlings will crack on the lower right side in the cooling exit ramp area.  The metal cooling exit ramps do not absorb enough of the vibrations from the prop-exhaust pulses.  The only way I know of to recuce or eliminate future cracks is to replace the metal ramp with a fiberglass ramp. | 	  
  Gary... is the damage less with a PowerFlow exhaust??   
 
  The pulses should not be hitting the cowling...
 
  gil A
 
  
 
  
  [quote]-----Original Message-----
  From: tiger862(at)ligtel.com
  To: teamgrumman-list(at)matronics.com
  Sent: Mon, 18 Sep 2006 9:37 AM
  Subject: lower cowling
 
       Is there anyway to repair cracks in a lower cowling on a 1978 Tiger, besides putting patches on the outside?[b]
 
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		flyv35b(at)minetfiber.com Guest
 
 
 
 
 
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				 Posted: Tue Sep 19, 2006 6:03 am    Post subject: lower cowling | 
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				Gary's right about the 78/79 models cracking.   But maybe it is due to the cowling flexing more due to the hole being cutout for  the exhaust tailpipe rather than the exhaust pulses.  Whatever it is the  stresses are more concentrated at the front corner of the air outlet "box" than  they are with the fiberglass outlets used on the earlier models.  And maybe  just patching the hole with an aluminum or composite filler patch (with the PF  internal design) will stiffen the cowl and make it better.  The PF  might be better (who knows) but it does require cutting out quite a bit of  material from the outlet duct for the tailpipe and this could change things as  well.  You could always install Gary's outlet ducts.
   
  It's not that big a deal to make a nice looking patch  with flush rivets.  Most repairs I have seen have be lazy with AN470 rivets  in a  haphazard pattern, or worse, pop or avex  rivets.
   
  Cliff
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		GrummanDude
 
 
  Joined: 15 Jan 2006 Posts: 926 Location: Auburn, CA
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				 Posted: Tue Sep 19, 2006 10:28 am    Post subject: lower cowling | 
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				Well, now, that is a great question.  I guess once the planes have been 
 is service with repairs AND a short stack powerflow for a long enough 
 time to see if the repairs crack.
 
 Gary
 
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  _________________ Gary
 
AuCountry Aviation
 
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