I thought long and hard about automatic pumps for the header and equally about the fuel vent in the header.My final decision in the end was no automatic pumps because I figured I would get used to them and quit managing fuel and sure enough one day they would fail and I would run the header dry. I never did the math but figured it could take some time to fill the header enough to lite the fire again and the ground may be there first.
After all this I decided my fuel system would be as follows:
Left and right pumps to the header from each wing.
left wing or right wing or header tank via fuel valve, I run primarily on the header but if I were to run it dry I can hit the engine boost pump and switch to either wing and have fuel. BTW my engine boost pump is in the back of nose gear well, low point in the system
I also plumbed my header tank vent on the top just before the gas cap, I have taken some crap on this but i never forget to turn my header fill pumps off as it starts spitting in my face long before it fills completely in flight. I never thought the vent under the cowling was a very good location.
Steve Alderman N25SA 170 TT
-----Original Message-----
From: Greenbacks, UnLtd. <N4ZQ@VERIZON.NET>
To: Lancair Mailing List
lml@lancaironline.net
Sent: Fri, Mar 22, 2013 8:16 pm
Subject: [LML] Re: 360 fuel transfer
About 20min into todays' flight and with the transfer pump switches set to auto,
the system failed. Actually it had failed before takeoff but I was unaware since
the header tank was full on takeoff. I observed the sight gauge level drop to
its normal pump on level and kept falling. The EI fuel gauge for the header tank
agreed and kept falling. Normally the pumps come on automatically at about
7.5gal but not today so I continued the flight and operated the transfer pumps
manually for the 2.5hr flight. About 5 min out from landing I again turned on
the transfer pumps manually and this time forgot to shut them off. :-(
Needless to say fuel was being pumped overboard as I taxied into the hangar....
So what went wrong? The auto transfer system is controlled by a solid state
relay from Perhelion Design and it works great.
However, the system failed due to the fact that one of the leads to the relay
from the buss had somehow slipped off its terminal on the relay(these terminals
are pointed down in this installation). A female spade connector that was
obviously just loose enough to wiggle itself off, did so. In the end, a simple
fix but it reinforces the point that none of our building work should be taken
for granted. Now the two power leads to the relay are secured with clear heat
shrink as well as lacing tape.
Angier Ames
N4ZQ
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