I am omitting the header tank and have a fwd hinged
canopy. I am planning on
mounting the hydraulic pump fwd of
the fwd hinge bulkhead most likely on the
nose gear tunnel. I
would like to review how builders have plumbed their
hydraulic lines when
the hydraulic pump is located fwd of the instrument
panel.
Thank
you for your help
John Kezele
John,
If you've already made up your mind to eliminate
the header, then read no further. If you're still considering it, you might
want to read this post of mine from March of 08 in reply to someone who was
considering the pros and cons of the header system:
I'll give you my opinion but I must warn you
it's quite biased. I'm a BIG proponent of header tanks. So much so that I'm
building one into the IV that we're building now. So here it
is:
PUT IN THE HEADER TANK
If you take a look
at accident statistics in Lancairs, the majority are pilot error. If we narrow
the list down to airframe problems, fuel related ones are at or near the top
of the list. The header tank system is beautiful in its simplicity. It's
gravity feed, you don't need to suck fuel UP to the engine and you can burn
both wings together. This feature alone eliminates big potential problems;
pump cavitation and unporting the fuel pickup to name a few. You can forget
the slosh doors.
A big practical as well as safety benefit is range. In
many instances, range is safety. In all instances, range is comfort. I really
like flying our 320 from Florida to Virginia knowing that if the weather is
crappy in Virginia, I've got fuel to fly comfortably to an alternate...like
Chicago, Montreal or Boston...really! The header tank will give you another 10
or 11 gallons. HOWEVER lets assume that the header tank gave you NO more fuel
capacity. Even then it would increase your practical range. Here's my
reasoning;
No header tank. You've got two very long, very flat fuel
tanks. The fuel quantity in a tank of this shape is difficult to measure
accurately. Besides, you really don't want to get the tanks very low for fear
of unporting the pickups. Generally in this situation I'd be getting pretty
nervous when the gauge, or the clock, said that I was getting anywhere close
to 1/4 tank. So in a 50 gallon system I'd want to be on the ground (in good
VFR weather) with no less than 13 gallons...probably more.
Header tank.
You've got the same wing tanks but now these are just aux tanks feeding the
main tank, the header. The header is a narrow, short (compared to the wings)
and HIGH tank. This shape of tank makes it easy to measure the fuel quantity
with a high degree of accuracy. The sight gauge is practically failure proof.
We've got a sight gauge and a capacitance gauge that always agree. If the
gauges say that I've got 5 gallons, then I've got 5 gallons. Running the wings
dry is absolutely NO problem. Once the wings are empty you KNOW that you still
have 90 minutes or more in the header. Because of the MUCH greater certainty
of useable quantity in the header, I am very comfortable flying down to 5
gallons or so. I KNOW that I can make 5 gallons last 45 minutes and I KNOW
that I, in fact, DO actually have 5 useable gallons. Same 50 gallons but now
I've got at least 8 more gallons that I'm comfortable using. That's 200
miles!
There's an old saying among the Bonanza guys that the most
effective SPEED mod that you can do to that plane is to add tip tanks. It
doesn't give you more knots, but it eliminates the fuel stop and THAT makes if
faster from A to B if you're going a long way.
If I've convinced you to
build the header tank, then here are some additional
recommendations.
Make it removable. Much easier for maintenance. (the
standard Lancair header can easily be made removable)
Put in a wing
tank cross feed. This is easy. Essentially what we have in our plane is a 3/8
tube running along the floor from one wing tank to the other wing tank. In the
middle (right under the console) I've got a ball valve. The ball valve has an
extended shaft connected to a knob on the console. Open it and the fuel can
gravity flow freely from one tank to the other. Close it and you've got two
separate tank systems. On either side of the crossfeed valve I've got "T's"
that connect to the respective fuel transfer pumps. With the crossfeed valve
open, EITHER pump can pump all of the fuel from BOTH wings since it will
gravity flow to the low point in the system (the crossfeed valve). A single
transfer pump failure still allows you to access ALL of your fuel. Without a
crossfeed, you not only limit your available fuel but you've just turned the
failed side fuel into ballast. You might not even be able to use all of the
good side fuel because of the unbalance problem.
Put in an automatic
fuel transfer system. A couple of float switches in the header and a simple
circuit will allow you to put the pumps to "auto" and they will keep your
header between full and 8 or 9 gallons with no action from you. The system
should also have a "manual" capability where you can turn the pumps on or off
as you wish.
Baffle the float switches. We've got our float switches in
a rather small sub compartment of the header with smallish holes to allow fuel
in or out. This makes sloshing or turbulence less likely to affect the
operation of the auto system. (the sight gauge taps off the same
area)
Add a third float switch (or Pillar Point sensor) in the header
at the 4 or 5 gallon level. This operates your LOW FUEL light (the big red
one) in case your automatic system fails and you don't notice, or in case you
need a reminder to land NOW.
*Optional... We also put float switches at
the bottom of the wing tanks that are connected through the pump circuit to a
"wing low" light. If the wing is empty (or close) AND you've got a pump on,
you'll get the light. This keeps you from operating the transfer pumps dry for
extended periods as well as giving you notice that you've emptied your
wing.
I've attached pictures that I hope will make some of this clear.
Please feel free to call or write (or visit) if I can help further. I'll be in
Milan, TN on the 1st. Are you near there?
Bill Harrelson
N5ZQ 320
1,450 hrs
N6ZQ IV under
construction