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Charles,
I calibrated my gauge by disconnecting my fuel system at the Gascolator and
using the boost pump to empty the tanks into containers. I then opened the
sumps to ensure that they were truly bone dry. The boost pump removed all
but a teaspoon or so of fuel.
My EI fuel gauge reads in eights and shows gallons as well. So...
I poured a gallon of fuel in each side and calibrated the gauge to read
zero. I poured 4 gallons in and calibrated that to be 1/8 tank and 4
gallons, another 4 gallons calibrated for 1/4 tank and 8 gallons, etc. until
I calibrated full to read 32 gallons. Now the full calibration is not
accurate because the capacitive sender was inundated with fuel at around 30
gallons. That means that I will read full until I get below that level and
also I should always have a gallon more than is indicated due to my zero
setting. I don't see that as much of a problem as I am more interested in
accuracy at 3/8 tank and below, and I try to always keep the fuel between
3/4 and 3/8 full.
I don't know at what level of fuel you might be able to unport the inlet,
but I suspect that you could do it with 3-4 gallons in the tank due to the
way the plane wiggles its tail in turbulence and the low dihedral.
I prefer not to cause the engine to run funny...it scares the hell out of
the mouse in my pocket! :>)
B2
-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of
Charles Brown
Sent: Saturday, July 20, 2013 12:41 PM
To: lml@lancaironline.net
Subject: [LML] Re: Fuel vol correction
OK, thanks Bill B, John B, and Bob P for inputs. Bill's info below is
interesting in that it confirms that 37 may be a good number if things are
working right. I did not sump the tank prior to filling, because I assumed
I'd put in 37 gallons -- but I may try that next time. However, it won't
prove much, will it? There *should* be *some* fuel left at the sumps,
regardless; that's where the unusable fuel hangs out, right?
I am the builder, I have photos proving (as I checked at the time) all the
little half-circle cutouts in the spar were present and not blocked by
ProSeal; the geometry of the rib caps makes it extremely unlikely that Hysol
could have blocked the cutouts at wing closing and at any rate, I measured
the 37gal volume long after the wings were closed. I can still hear the
gate valves slapping whenever I rock the airplane on the ground with partial
fuel, so they're working; and there's no venting issue. I slipped the plane
in flight to get the last of the fuel, but maybe not long enough? Once the
engine sputters, it could take many seconds to re-establish flow?
Hmmmm.....
Of course it's possible that some blockage has occurred, I can check that
out with a borescope, sounds like fun. Thanks guys, I'll let you know if I
figure it out. Good ideas in Bob's article.
CB
On Jul 19, 2013, at 2:51 PM, Bill Bradburry wrote:
Charley,
Did you sump the tank prior to refilling it to ensure that it was truly
empty? You may be looking at 3 gallons un-usable. The Legacy wings have
little dihedral and there is a lot of sloshing. You may have unported the
fuel outlet finger strainer and made you think the tank was empty.
When I calibrated the fuel gage on my Legacy with speed brake wells, both
tanks were 36 gallons filled to the bottom of the fuel inlet. 37 gallons
makes sense if you don't have the speed brake wells.
B2
-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of
Charles Brown
Sent: Friday, July 19, 2013 7:22 AM
To: lml@lancaironline.net
Subject: [LML] Fuel vol correction
I may have provided some bad info in the past. I stated that the fuel vol
in my wing tanks was 37 gal per side; attributing the extra to the complete
absence of speed brake provisions. However, I just got around to exhausting
a fuel tank in flight, and refilled it with 34 gallons. Of the many
possible variables, the one that seems most dubious is the accuracy of the
1/2 gallon measuring cup that was the basis for the original calibration.
I"m still sorting through this one.
Charley Brown
Legacy 275 hr
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