Today's Message Index:
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1. 04:08 PM - Vapor pressure and the case of the missing fuel? (MPPalmer@aol.com)
2. 06:21 PM - Data points to wing leak (MPPalmer@aol.com)
3. 07:04 PM - Re: Data points to wing leak (James Robinson)
4. 07:56 PM - Re: Data points to wing leak (Bruce Gray)
5. 09:41 PM - Re: Data points to wing leak (RObin Young)
Message 1
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| Subject: | Vapor pressure and the case of the missing fuel? |
After blowing the vents out good and hard two days ago and not seeing
anything more to fix, I'm starting to button the plane back up. (I'll plan on reverse
flushing the transducer next month, after my eye surgery, if this problem
still isn't solved. But I'm having a hard time believing the Flowscan is off.
That would imply we were burning 7.8 GPH all of a sudden when we've been running
in the high 6's, low 7's for years now. I suppose if the cam were worn....but
there wasn't metal in the oil filter last time.) I put a new piece of aluminum
tubing on the center section fuel vent, extending the assembly a few more
inches into the airstream to pressurize the tank better. The old one was down to
less than 2 inches from the skin. An interesting observation today.
As you may recall, I topped the tanks on Wednesday. Did it myself. Just for
grins, I checked the tanks today. (Friday.) The main tank is down about 3 to 4
gallons! I'm pretty sure I didn't blow 3 to 4 gallons out the vents when I
was testing. Where is the fuel going? (Surveillance tape shows no one in the
hangar stealing fuel.)
I tightened one fuel cap some more, although I thought it was fairly tight
already. I can't smell any fumes from that cap.
The header tank is staying right where it's been for the week. It's only the
main that's apparently gone down.
I left a sample cup full of fuel out to see if it will all evaporate by
tomorrow. I'll plan to check the level tomorrow in the main and if it hasn't
changed, I'll plan to re-top off the tank again, to see if the level really is
changing. If it does, then, as Sherlock Holmes would say, it must be a leak in
the
wing somewhere, no matter how improbable.
[Interestingly, we had a big thunderstorm blow through here last night. I
don't know what the baro pressure did for the evening, but I've noticed that pump
bottles of epoxy (The West System) routinely dribble epoxy when not in use. I
think it's baro pressure changes and a one way valve moving fluid. Exhaling,
if you will. I wonder if I have a similar situation with the wing, although I
don't know what the one way valve would be. (I don't hear the B rib check
valves slap anymore, but there were bypass holes in the ribs anyway.)
One would think I would smell fuel in the cockpit if it were leaking past the
spar, since there are holes from the cockpit to each bay in the wing through
the ribs for the aileron push tube. But then again, the fuel doesn't seem as
stinky as it sometimes is, and maybe I'm not noticing it. (This would serve me
right. When I do the annual, I usually take the flashlight and mirror and peer
all around the inside of the bays, looking for fuel stains. I didn't do that
this time.) When I had the vent tubes disconnected in the cockpit this week, I
didn't notice the usual overpowering smell of avgas like I usually do when
there's a bona fide leak.
Years ago I tore the airplane apart for a few months, trying to find what
smelled like a dead mouse in the wing. Turned out to simply be a highly sulfured
batch of AvGas that season! This year, I don't notice fuel vapors at all. Now
I'm wishing they'd put the sulfur back!
I'm still looking for that "Eureka!" moment, when I suddenly understand what
the problem has been all along regarding this case of the missing fuel. So
far, I've not had that. And that bothers me.
Maybe after checking the tank level again tomorrow, I'll know more.
Mike Palmer <><
<BR><BR>**************<BR>Get the scoop on last night's hottest shows and the live
music
scene in your area - Check out TourTracker.com!<BR>
(http://www.tourtracker.com?NCID=aolmus00050000000112)
Message 2
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| Subject: | Data points to wing leak |
After my last post, I thought about this a little more.
If I've lost 4 gallons of fuel in 48 hours, that's a leak of 0.08 GPH. In
other words, a drip.
So it's seeming that I have a wing leak somewhere, as someone suggested
before. I suppose at this slow rate, it might be hard to smell given the rate of
evaporation in a hot Phoenix hangar.
I'll plan to pull the inspection panels and hope something obvious (and easy)
shows up.
Anyone know (like Bruce) where fuel leaks tend to occur most frequently? I'm
guessing more in the middle of the tank, where pressures are highest.
Thanks,
Mike Palmer <><<BR><BR><BR>**************<BR>Get the scoop on last night's hottest
shows and
the live music scene in your area - Check out TourTracker.com!<BR>
(http://www.tourtracker.com?NCID=aolmus00050000000112)
Message 3
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| Subject: | Re: Data points to wing leak |
Mike
With a fuel leak like that you would see the blue dye stain even without an
y apparent- fuel.- I have had a few occasions where my quick drains did
n't seal and I see a blue spot on the floor.- That would also be the same
for a leak across the spar cap or at the main spar attach bolts.- The bl
ue dye in the fuel stains everything.
Jim Robinson
Glll- N79R
--- On Fri, 7/11/08, MPPalmer@aol.com <MPPalmer@aol.com> wrote:
From: MPPalmer@aol.com <MPPalmer@aol.com>
Subject: Glasair-List: Data points to wing leak
After my last post, I thought about this a little more.
If I've lost 4 gallons of fuel in 48 hours, that's a leak of 0.08 GPH. In o
ther words, a drip.
So it's seeming that I have a wing leak somewhere, as someone suggested bef
ore. I suppose at this slow rate, it might be hard to smell given the rate
of evaporation in a hot Phoenix hangar.
I'll plan to pull the inspection panels and hope something obvious (and eas
y) shows up.
Anyone know (like Bruce) where fuel leaks tend to occur most frequently? I'
m guessing more in the middle of the tank, where pressures are highest.
Thanks,
Mike Palmer <><
**************
Get the scoop on last night's hottest shows and the live music scene in you
r area - Check out TourTracker.com!
(http://www.tourtracker.com?NCID=aolmus00050000000112)
=0A=0A=0A
Message 4
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| Subject: | Data points to wing leak |
I'd check your sump drains first. The O rings do wear.
Bruce
<http://www.glasair.org/> www.Glasair.org
-----Original Message-----
From: owner-glasair-list-server@matronics.com
[mailto:owner-glasair-list-server@matronics.com] On Behalf Of
MPPalmer@aol.com
Sent: Friday, July 11, 2008 9:19 PM
Subject: Glasair-List: Data points to wing leak
After my last post, I thought about this a little more.
If I've lost 4 gallons of fuel in 48 hours, that's a leak of 0.08 GPH.
In
other words, a drip.
So it's seeming that I have a wing leak somewhere, as someone suggested
before. I suppose at this slow rate, it might be hard to smell given the
rate of evaporation in a hot Phoenix hangar.
I'll plan to pull the inspection panels and hope something obvious (and
easy) shows up.
Anyone know (like Bruce) where fuel leaks tend to occur most frequently?
I'm
guessing more in the middle of the tank, where pressures are highest.
Thanks,
Mike Palmer <><
**************
Get the scoop on last night's hottest shows and the live music scene in
your
area - Check out TourTracker.com!
(http://www.tourtracker.com?NCID=aolmus00050000000112)
Message 5
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| Subject: | Data points to wing leak |
I'll plan to pull the inspection panels and hope something obvious (and
easy) shows up.
Anyone know (like Bruce) where fuel leaks tend to occur most frequently? I'm
guessing more in the middle of the tank, where pressures are highest.
Thanks,
Mike Palmer <><
Mike, the forward attach brackets for the wing are through bolted to the
spar. Early builders had a problem of seepage around the bolts and a fix
was added to the manuals but, at #36 to fly, I don't know what the fix is.
You might check under the seat pans for stains but you would have noticed
the odor if a is stain there.....this leads me to think there may be a
siphon due to low pressure under the wing fairing and fuel is being pulled
from around the attach bracket outside the cockpit. It is a long shot but
worth a look; first at the top of the brackets and then under the fairings.
Godspeed, Robin
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