bdelmonte

In terms of terminology, just so you know, a "short" means a direct
electrical connection. So a fuse is "shorted" when it is good. When
a fuse "fuses", then it is "open". There are many kinds of fuses,
one kind is called a "slow blow" and allows higher current to pass
for a short time before it blows.

You will not find fuses on many (?any) electrically powered
helicopters.

This is a clue, I think, that fuses are generally
undesirable. If the fuse protects the tail motor circuit,
if the tail motor draws too much current, or there is
a "short" to something that allows a current high enough to blow
the fuse, or the tail motor will stop working and you will crash.

I would pull the tail motor wires out of the tail boom. Inspect them
carefully, especially in the area where the tail motor mount screw
goes into the boom. Take a resistance reading across the tail
motor wire with the motor end and the 3 in 1 end disconnected.
You should get infinite resistance, i.e. an "open".

Re your tail motors failing. This is unlikely to be caused by
excessive current. Even if the motor leads were shorted, the motor
itself probably would not be damaged. The problem with
the direct drive on version 3, which I tried on a version 2 with
version 3 parts is overheating. The brushes in the motor are
connected to the leads outside the motor by a "plastic rivet".
If the motor gets hot enough, the plastic softens and brush holder
will move and stop making a hard enough contact with the
commutator. Also, if the motor gets hot enough, it can
demagnetize the magnets. By drilling out the two tabs on the
end of the motor, you can pull the plastic end cap off and see
for your self that you have plenty of "brush" left.

A couple things you can do. One, after you've soldered on the
tail motor wires, lay a thick coat of household cement over the
whole plastic end plate. This will keep the wires from moving.
If the wires move or vibrate, they can cause the "plastic rivet" to
loosen and the brushes will then move.

Two, get an Align aluminum tail boom servo holder. Drill two
holes in the end of the tail boom, top to bottom, and mount
the bracket. The hole that goes over the boom will fit a
tail motor just right. Run the tail motor wires outside the boom.
If I can, I'll post a picture. This give you an added heat sink as
the bracket absorbs heat and so does the aluminum tail boom.

Another option is to convert to a geared tail. I've got 3 axe's
all with geared tails and they work fine. I used the servo bracket
described above to mount a geared tail and the tail motor stays
very cool.

Last on tail motors, let the motor cool off completely between
flites.

Now on to the 3 in 1. If you have a "short" anywhere in the tail
or main motor wires, too much current is going to go thru the
board and burn up a component. Otherwise, if a board fails
it's probably crash damage or a manufacturing defect. One of
axe's has almost 400 flites and the version 2 board is still
working correctly.

You can buy an after market brushed motor esc and they are
cheap, at www.hobbyking.com. I've got a couple but have not
hooked on up yet. For the tail motor, I've used the C12 esc, which
is expensive but works well.

Finally, see my next post re the $36 450 size heli from Hobby King.

Good luck. While the Axe has many issues, I still fly mine every
day and like the ability to keep learning by garage flying regardless
of the weather.