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Air Compressor Warning

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vectorwarbirds(at)aol.com
Guest

Posted: Sun Aug 12, 2007 9:02 am Post subject: Air Compressor Warning

We just completed rebuilding three air compressors pulled from 400 to 1200 hour engines and feel you all should be aware of what we found.  First you should know that there are THREE valves at and in the compressor.  One is external at the cylinder and two are internal valves. One is located in the cylinder head and the other in the piston itself and the most important.  The piston valve and its airways were virtually clogged with burned oil residue, the airways are 5/32" in diameter are run down and out the sides of the piston.  Those holes were clogged to about the size of a safely wire when we removed the piston.  You will most likely NOT be able to remove the piston valve yourself without the special tools to do so. There are both vertical and horizontal holes running through the piston so the crown valve has to be removed to clean them all. 

 

 As a test we submerged one of the uncleaned and un-assembled pistons in carbon cleaner in our heated ultrasonic cleaner and left it for 48hrs to just see if this would clear the passageways and clean the valve without having to disassemble the valve system, almost zero cleaning after we took the thing apart so this is not an option. 

 

 The piston valve is just like the external valve, poppet valve and spring. They were completely clogged as well as all the passageways.

 

 From this experiment we are going to pull our newly cleaned compressor in two years to see what kind of build up has occurred during that time, then we will know a schedule for cleaning.  So in closing we would recommend that everyone take a hard look at pulling the cylinder and having the system cleaned at the least.  You can pull the cylinder only as there is no need to remove the compressor body from the engine for this program.  We also replaced all the nuts with locking 10mm head size to make R&R easier in the future. 

 

 We believe that at least one aircraft has had an engine failure resulting from the loss of the compressor which sheared an accessory drive gear.  (CJ6).  If the valves and holes become totally clogged the compressor is working against itself to compress air that has nowhere to go, major heat buildup as well all know in compressors.  We also recommend a compressor overboard or dump valve to let the compressor 'freewheel' when building air is not required.  We open the valve on climb and close it when down wind. (Ck list). 

 

 Let us know if you have any questions.

 

 Vector Aviation USA 

 -- 

 Bunndini

 

 "Wasn't there something in your life worth losing everything for?"

 Mulay Achmed Mohammed el-Raisuli the Magnificent, Lord of the Riff, Sultan to the Berbers - 1902 

   

  [quote][b]

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brian-1927(at)lloyd.com
Guest

Posted: Sun Aug 12, 2007 11:04 am Post subject: Air Compressor Warning

On Aug 12, 2007, at 1:01 PM, vectorwarbirds(at)aol.com wrote:



 	  Quote: 	
		   The piston valve and its airways were virtually clogged with burned  

 oil residue, the airways are 5/32" in diameter are run down and out  

 the sides of the piston.  Those holes were clogged to about the  

 size of a safely wire when we removed the piston.


	


This strikes me as a call for an oil less prone to breakdown and  

coking. An engine that has been flown on lower-quality mineral oil  

might be more likely to have this type of problem.



--

Brian Lloyd                         3191 Western Drive

brian HYPHEN 1927 AT lloyd DOT com    Cameron Park, CA 95682

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry



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