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  #11  
Old 03-15-2016, 01:04 AM
dhmoose dhmoose is offline
 
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Quote:
Originally Posted by rzbill View Post
There is a fine screen filter in the AFP pump system (between the seats). Its the big gold anodized cylinder. Contact Airflow Performance in Spartanburg, SC for details if you do not have original documentation.

There is also a VERY VERY fine screen filter in the SilverHawk fuel injector servo body. Contact Precision Airmotive for documentation regarding maintenance.

Both of these filters should be inspected and cleaned at the annual condition inspection.
Bill, you made me curious and I referenced the Precision Airmotive EX-5 servo manual. It reads " The airplane's fuel filter needs to be maintained to ensure that the servo gets clean fuel. The fuel filter inside the servo is a last chance filter. This filter does not need to be checked or cleaned unless it is suspected that contaminates have entered the fuel line after the aircraft's fuel filter."

Hopefully, I saved you some headaches at annual
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  #12  
Old 03-15-2016, 05:40 AM
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rzbill rzbill is offline
 
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Originally Posted by dhmoose View Post
Bill, you made me curious and I referenced the Precision Airmotive EX-5 servo manual. It reads " The airplane's fuel filter needs to be maintained to ensure that the servo gets clean fuel. The fuel filter inside the servo is a last chance filter. This filter does not need to be checked or cleaned unless it is suspected that contaminates have entered the fuel line after the aircraft's fuel filter."

Hopefully, I saved you some headaches at annual
Hmmm. Now things start to make sense. If one externally filters to the same particle size as the internal screen (the 32/35 mesh requirements noted earlier in thread) then the internal screen will never catch any debris. No need to check it.

In the vans std setup, the AFP is a coarse screen so the EX5 screen may pick up debris. I'll keep cleaning it for that reason. Thanks for the info!
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Last edited by rzbill : 03-15-2016 at 05:42 AM.
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  #13  
Old 03-15-2016, 12:03 PM
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Thermos Thermos is offline
 
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Originally Posted by rzbill View Post
I see the note about 32 micron filtered fuel supply by Precision but I have not found reference to what the internal screen is. Just by observation, I have a hard time believing it is finer than 32.
I have an Andair 62 micron filter upstream of my Andair boost pump. Based on information I'd previously received from Mattituck, I hadn't planned on installing another filter after the boost pump but I decided to email Precision and confirm what I'd heard earlier from Mahlon. Their words were that anything finer than the 70 micron screen in the servo would be acceptable.
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  #14  
Old 03-15-2016, 07:08 PM
Robb Robb is offline
 
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Thanks for the info. I did find the filter it is down in the enclosure between the seats and it is a large red cylinder type that is cleanable. It appears top be a bitch to get at. Funny thing is I see no mention of any maintenance in the log books anywhere. I have 230 hrs TT so I doubt its bad but we will see.
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  #15  
Old 03-16-2016, 06:10 AM
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Kahuna Kahuna is offline
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Quote:
Originally Posted by rzbill View Post
Hmmm. Now things start to make sense. If one externally filters to the same particle size as the internal screen (the 32/35 mesh requirements noted earlier in thread) then the internal screen will never catch any debris. No need to check it.

In the vans std setup, the AFP is a coarse screen so the EX5 screen may pick up debris. I'll keep cleaning it for that reason. Thanks for the info!
Wait wait. This is not true. The servo screen is the screen of last resort. Debris can come from a number of places including hoses, pumps, diaphrams, etc. Check it per manufacturers specs and dont neglect it due to other filters up stream regardless of micron.
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  #16  
Old 03-16-2016, 12:28 PM
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RV7A Flyer RV7A Flyer is offline
 
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Originally Posted by Kahuna View Post
Wait wait. This is not true. The servo screen is the screen of last resort. Debris can come from a number of places including hoses, pumps, diaphrams, etc. Check it per manufacturers specs and dont neglect it due to other filters up stream regardless of micron.
Right..and the manufacturer's instructions say:

Quote:
This filter does not need to be checked or cleaned unless it is suspected that contaminants have entered the fuel line after the aircraft's fuel filter."
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  #17  
Old 03-16-2016, 12:39 PM
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JonJay JonJay is online now
 
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Originally Posted by RV7A Flyer View Post
Right..and the manufacturer's instructions say:
I had an occasion to call them recently and asked as this had just come up. Despite what the instructions say, they do recommend you check it occasionally. It is super easy to do. I do mine at each CI.

PS - I have never found anything in it. Nothing, zilch, nada. I only occasionally find stuff in the upstream filter. A microscopic piece of fuzz, a pin head spec of something black, although just yesterday doing my CI, I found a very small goldish metallic spec, like super tiny can hardly see with the naked eye. I think it might have been from the fuel tank drain as I removed them to drain that tanks, or it could have been from the selector valve as I removed it for replacement. Who knows.
Anyway, nothing exciting....
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Last edited by JonJay : 03-16-2016 at 12:53 PM.
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  #18  
Old 03-16-2016, 05:07 PM
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I had an occasion to call them recently and asked as this had just come up. Despite what the instructions say, they do recommend you check it occasionally. It is super easy to do. I do mine at each CI.
I'll go by what they've *written*. Anybody can say anything over the phone.

Plus...the more stuff you needlessly take apart, the more chances you get to mess something up, and the last thing I want to mess up is my *fuel system*. Remember the Waddington effect?

Manual says don't take it apart unless you (have or) suspect contamination upstream. Sounds like good advice to me.
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  #19  
Old 03-16-2016, 09:32 PM
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rzbill rzbill is offline
 
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Originally Posted by Kahuna View Post
Wait wait. This is not true. The servo screen is the screen of last resort. Debris can come from a number of places including hoses, pumps, diaphrams, etc. Check it per manufacturers specs and dont neglect it due to other filters up stream regardless of micron.
Hi Mike,
I may have mislead you with the way I wrote my post. I meant to imply that I would keep cleaning the servo filter.
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  #20  
Old 03-17-2016, 10:57 AM
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JonJay JonJay is online now
 
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Originally Posted by RV7A Flyer View Post
I'll go by what they've *written*. Anybody can say anything over the phone.

Plus...the more stuff you needlessly take apart, the more chances you get to mess something up, and the last thing I want to mess up is my *fuel system*. Remember the Waddington effect?

Manual says don't take it apart unless you (have or) suspect contamination upstream. Sounds like good advice to me.
Peter is who I spoke with. He has been there in the tech support role for quite a long time and knows the product very well.
However, I get what you are saying and the choice is certainly yours to make. I don't think inspecting this part is needless, but we can agree to disagree.
I would say that I am probably your best advocate. I have never found anything in that screen, ever.... but I will still keep looking.
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Last edited by JonJay : 03-17-2016 at 11:00 AM.
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