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ACRO E-mail Archive Thread: Fueling Extra 300

Thread: Fueling Extra 300

Message: Re: Fueling Extra 300

Follow-Up To: ACRO Email list (for List Members only)

From: FJensen210 at aol.com

Date: Sun, 08 Dec 1996 05:52:30 UTC

Message:

  I do not routinely fly the Extra 300, but I did participate on an extended
flight test program last year (midwing) that required multiple flights in a
variety of fuel loading configurations.  This began by completely defueling
the airplane, starting from a known zero baseline.  Each flight would start
with a specific amount of added fuel, and consumption monitored with the fuel
flow computer.

As you point out, the main (acro) tank is gravity filled from the wing tanks.
 When you dip check the wing tanks to verify total airplane fuel, you assume
the main tank has filled completely.  Over a period of two weeks of flight
tests and multiple refuelings, this usually happened worked for us.  On two
occasions, however, it didn't.

In the first case, we were puzzled during preflight when a dip check of the
wing tanks indicated more fuel present (about four gallons) than what we had
planned.  We lifted the tail to level flight position momentarily, and set it
back down.  The dip stick check of the wing tanks then immediately showed
that lower level that we had expected.

When the same thing happened again several days later, I climbed into the
front cockpit and tapped and listened along the back of the main tank to
confirm that it had not completely filled.  Picking up the tail of the
airplane repeated the results.

This is not supposed to be able to happen, but did.  In both cases, there had
been plenty of time since refueling, and the indicated levels on the dip
stick had stabilized.  Perhaps it had something to do with the hot
temperatures of the California desert.  Whatever the reason, the main tank
"tap check" became a standard preflight item from that point forward.  

We would not have picked this up had we not been tracking fuel consumption
and loading so closely.  Miscalculating just a couple of gallons of available
fuel in an already lean fuel loading profile for aerobatics could obviously
lead to problems.

Regarding your question of aerobatics outside of the flight manual, consider
that what is safe is not necessarily legal.  That may only become an issue if
any incident happens to bring it to the attention of your friendly FAA.  

As you know, the envelope of the EA300 is generous in the normal category,
but considerably narrows in the aerobatic category.  The airplane must comply
with the generic airworthiness standards of FAR #23 designed to protect the
pilot from himself, consistent with the Cessna 150s, etc.  It is remarkable
that Extra has been able to achieve this level of aerobatic performance in a
type certificated airplane.

In my opinion, the EA300 is an exceptionally honest and safe aerobatic
airplane.  We flight tested the airplane outside of its certification
envelope for aerobatics --  in terms of aerobatic gross weight, aft CG and
with limited wing fuel. This included multiple spins, upright and inverted.
 This was, however, done on an FAA approved test plan, under a temporary
experimental airworthiness certificate issued for the purpose of the flight
testing, and with the agreement of the insurance company.

The fuel profile for legal aerobatics is tight, but workable.  With multiple
partners flying the same airplane, however, the opportunity for fuel
mis-management could be increased.  If you find that the flight manual
constraints are too significant for your purposes, and all of you are
operating the airplane for personal enjoyment only, you might consider
converting to an experimental airworthiness certificate to slightly increase
the envelope while you own the airplane.  This could be done on the basis of
the conservative limitations that you describe.  It is not that hard to
convert back to a standard airworthiness certificate at time of resale, as
long as you do not modify the airplane.  Typically requires an annual
inspection and FAA signoff at that time.

I hope this is of some use.  Enjoy this fine airplane.


Finn Jensen

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