Mailing List lml@lancaironline.net Message #42688
From: Craig Berland <cberland@systems3.net>
Sender: <marv@lancaironline.net>
Subject: [LML] Re: Boost Pump
Date: Thu, 14 Jun 2007 14:32:51 -0400
To: <lml@lancaironline.net>
I'm sorry but I have too many irons in the fire for much of a detailed response.
Craig said,
There is a variable orifice as well as the bypass valve involved in the fuel return system that will affect fuel rate beyond the return line size
 
Craig,
can you say a little more about these features?
What is a variable  orifice?   Off deck pressure via the aneroid. (piston and orifice)
Where is it in relation to the boost pump, eng pump, metering unit?  All of these features are built into the engine driven fuel pump.  The engine fuel pump controls the pressure going to the metering unit.  The boost pump is upstream to the engine pump and the metering unit is downstream of the engine pump.
Where is the bypass and what does it take to open it?  The bypass is in the engine pump. I'm not sure how this all interacts. There is also a recirculation path going back to the vapor separator. The recirculation path is blocked at full rich and fuel flow should be blocked at idle cut off.  Not one thing controls the bypass fuel.
 
This may be more confusing than helpful.  Hopefully someone will correct me if I have made a mistake in my haste.
Craig
Panel done is 2 weeks
1st flight is getting close
 
thanks,
 
Colyn
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