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Date: Sun, 27 Jan 2013 13:30:22 -0500
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From: George Wehrung <gw5@me.com>
Subject: Question about Dukes Fuel Pumps

All,

A couple of questions about Dukes electric boost pumps.  If the engine driven fuel pump fails, can the Dukes electric boost pump, in the low flow mode supply enough fuel to keep the IO-550 running, at what I would guess a lower power setting to find a place to land?

I have noticed that some installations have both a prime button and have a separate high flow mode incorporated into a a HIGH-OFF-LOW rocker switch.  My airplane only has a LOW-OFF selection for the boost pump in addition to the push to engage Prime mode, which I have learned is the High Flow mode for the boost pump.  

It does not seem to make sense that if one lost the engine driven fuel pump that you would have to hold the prime button in order to have High Flow mode from the electric boost pump to keep the engine running.  Or, should my airplane have the HIGH-OFF-LOW boost pump rocker switch installed?

There doesn't seem to be any spec sheets available on the flow volume in the High and Low modes of the Dukes Electric Boost pump.

Lastly, from what I have learned in the build manual that there must be an internal bypass in the engine driven fuel pump if it fails?  The plumbing seems to be as follows: Fuel tank, fuel tank selector valve, electric boost pump, firewall, gascolator, engine driven boost pump, and then fuel distributor, and then injectors. I know there is a return line from the engine driven boost pump back to the fuel selector valve. 

Thanks for the help

George