Mailing List flyrotary@lancaironline.net Message #19310
From: Bobby J. Hughes <bhughes@qnsi.net>
Subject: RE: [FlyRotary] Re: Fuel system Sketch Rev1
Date: Wed, 23 Mar 2005 09:05:18 -0600
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Message
Rusty,
 
Thanks for the reply.
 
 
You've come to the wrong list :-) 
 
I am afraid of the other list so I will stick with this one. :)
 
Note that fuel system threads are one of our most popular, and everyone has an opinion.  
 
I think the fuel filter threads are Saginaw not NPT. 
 
 if your pumps are really in the cockpit as they appear, there should be no chance for fuel to be boiling.  With that in mind, you could probably skip the bypass around the regulator.  
 
Two reasons to keep the bypass. One. Vapor lock protection?????.  It is a mandatory AD on the Egg Subi's after the two or three vapor lock problems they had last years.
Mark Steitle reported and I observed his engine would restart after running a tank dry and switching to the other with the bypass in place. It would not restart before this without releasing pressure ahead of the pump. 
 
lines are HUGE before the fuel manifold.  
 
Lines are based on Andair's recommendation for line sizes with their Fuel Selector.   I need 235- 260 hp. Andairs data is for a Lyc or Cont. Can we use smaller lines with the  38-42lbs we are running? Not sure what the IO's run for fuel pressure.
 
somehow it seems wrong to have the two filters in parallel after the fuel manifold.  I would normally expect to see one after each pump.   All you're really doing is doubling the size of your filter, and these are pretty huge already. 
 
Twice in my life I have experienced partially clogged fuel filters in a car. Of course I was much younger and I am sure they was not serviced properly. The idea was to provide redundancy so either pump could use either (both) filters. Also a nice place for sensors. However, it added extra connections. :( 
 
Bobby
 
Education and recreation right?
 
 
 
 
 
 
 
 
 
 


From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Russell Duffy
Sent: Friday, March 18, 2005 4:51 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Fuel system Sketch Rev1

Need a sanity check.  
 
You've come to the wrong list :-) 
 
I don't see anything wrong with it, but I will make a couple comments.  Note that fuel system threads are one of our most popular, and everyone has an opinion.  
 
- if your pumps are really in the cockpit as they appear, there should be no chance for fuel to be boiling.  With that in mind, you could probably skip the bypass around the regulator.  
 
- lines are HUGE before the fuel manifold.  
 
- somehow it seems wrong to have the two filters in parallel after the fuel manifold.  I would normally expect to see one after each pump.   All you're really doing is doubling the size of your filter, and these are pretty huge already. 
 
Cheers,
Rusty (gotta go do some lay-ups, and I wish I meant basketball)
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