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One thing occurred to me, James.
After some work on his Ercoupe, an A&P w/IA friend of mine was not getting
fuel flow. It bugged the both of us. He discovered that the connector
through the firewall was leaking air. Thus, the pump would pump air, not
filling the header tank. This one can be a bugger to find. The fix is to
tighten the fitting.
Yes, I remember those mountains!
Percy in NM, USA
-----Original Message-----
From: jls [mailto:[EMAIL PROTECTED]
Sent: Sunday, October 23, 2005 4:07 PM
To: [EMAIL PROTECTED]; Ercoupe Technical Discussion (moderated)
Subject: Re: [COUPERS-TECH] Cross-Country Glitches
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advice in this forum.]----
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>; <[email protected]>
Sent: Sunday, October 23, 2005 5:30 PM
Subject: Re: [COUPERS-TECH] Cross-Country Glitches
> James: It sounds to me like you need to have a good look at the entire
fuel
> system.
Yes, we did. We also flew the aircraft for several hours before this
cross-country without any glitches before the x-country. In other words the
header tank was keeping a good head of fuel which was replenished by the
wing tanks.
Start by checking the two valves, one feeding the fuel pump from the
> wing tanks and one feeding the engine from the header tank. Once you have
> ascertained that both of the valves are opening completely (I have seen
them put
> together wrong so they do not fully open (even done it myself)), then
check
> the lines from the firewall to the pump. (I am assuming you have already
> cleaned the pump and replaced the gaskets while properly checking the
fuel pump
> cover bolt torque).
Yes, we did and what it the torque value? I have left the little red
pamphlet service manual (from Univair) at Rutherfordton and am in Asheville
preparing to drive to Sevierville.
The bottom line (from the bottom fitting) goes to the
> fitting on the rear of the pump, which is the inlet. The top line comes
from the
> more forward fitting on the pump (and should have a restriction in it)
The flow restrictor is in the line, not in the pump? OK, how would we
identify it? It would be something of a diameter pinch in the line?
Please describe it.
which
> is the pump discharge.
Yes, we have all that plumbing straight and worked out. We verified it was
connected properly by tracing it all out and then running air through the
lines.
This line comes into the header tank from the rear.
Yes. That's hooked up correctly. The aircoupe manual does have a good
diagram or drawing showing how to troubleshoot the fuel line connections and
assure they are all working properly.
> There is another set of lines that come out of the rear of the
fuselage
> tank, goes into a tee which has two lines that go to either wing tank.
> Obviously all of these need to be open and feeding fuel easily.
> The lines from the wing tanks come under the floor boards to a tee in
> front of the passenger seat then go forward to just ahead of the
instrument
> panel where the line goes up to the valve on the right side panel. Then
from the
> valve out to the fuel pump.
> I know you have had all of these out of the plane, and have most
> certainly checked them carefully, but it may be worth a second check.
They have been checked and double-checked.
> You should have put new gaskets on the fuel caps when you had the
tanks
> out to be repaired.
We'll do this, have not previously done it and thank you for this advice.
Both of the wing tank caps should fit tightly.
Well, as a matter of fact they do. They are tight as a tick, so tight they
are hard to turn and remove.
It sounds
> like you may not have enough tension on the springs that hold the cap
down on
> the one that fuel leaked from,
The leak follows the cap with the ram-air hole. If you switch the cap to
the other tank, the leak goes with it. The other cap does not leak.
The fuel spills during flight from the ram-air hole, NOT from around the
lid, or that is the way that it appears to us in the cockpit.
however, if there is some problem in the
> lines from the fuel pump, i.e. hooked up backwards, especially if you do
not have
> the restrictor in the fuel pump line, it is possible that you could pump
> fuel out of the header and over-fill the wings.
> You did not indicate the serial number of the Alon, but if it has
fuel
> caps that have vent holes in them, I am assuming you have had one or more
> service bulletins installed.
I received a list of service bulletins from Skyport and find that compliance
with the bulletin which requires removing the header tank and cutting a
slice out of the top of it and installing new vents is too onerous. We'll
do it, of course, if we have no other way out.
I believe that the original wing tank caps were the
> thermos bottle type and only the header tank was vented.
> I apologize for the disjointed discussion of the fuel system. I did
not
> discuss the overflow vent for the header tank, but it should not be the
> problem.
> Lynn Nelsen
>
Here is a list of what I was about to publish in the mail list, particularly
in response to a reply of our 'couper friend Ed Burkhart:
1 Gal fuel left in header tank upon landing (owner was sorely affrighted)
Plenty fuel in wing tanks
Wire gauge in front of windscreen bottomed out and nipple on top
disappeared. (trembling and some praying inside aircraft)
During flight over mountains, stream of fuel was observed to flow out of
ram-air hole in fuel filler cap ON THE WING
Not being that familiar with the beast, it was near-death experience (for
owner too)
After putting down at airport, pump tested by turning prop with starter ---
no gasoline flowed
A&P/IA trouble-shot the pump from every perspective and declared it
defective.
(He has worked on Ercoupes before.)
He put his mouth over the inlet on the wing tank and blew into the tank to
make sure the lines were clear and connected correctly (They were--- In
addition to which I tested all of them and the petcocks when I was
installing all three tanks.
I agree with him and so did a salty A&E also in attendance during the tests
Owner said fuel had not ALWAYS streamed from the wing tank lid, which makes
me wonder:
Do we have a bad flow restrictor, or maybe none at all? I suppose one could
fabricate a flow restrictor by drilling a hole of the proper diameter in a
tube-shaped billet of aluminum.
I work on 172's, Pipers, Taylorcraft, and Cessnas of all types. The shop
manuals are just about as thorough as one could ask for, especially Cessna
manuals which have great drawings. However, I have yet to see a thorough
manual on an Aircoupe and the parts manual is, well, woefully incomplete.
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