On Tue, 3 Nov 2009 16:01:25 -0500, "Peter Dohm"
wrote:

wrote in message
.. .
On Tue, 3 Nov 2009 06:55:10 -0800 (PST),
wrote:

On Nov 2, 11:08 pm, wrote:

Define "substantial" and a fuse or breaker WILL disconnect it if
something goes wrong.

And if that fuse or breaker is in the cockpit, you still have
a live feed to it even if it trips. If it's next to the battery
somewhere else, you can't shut it off, reset it or replace it in
flight.

Dan
NEVER attempt to replace a fuse in flight. Assume it blew for a
reason. Concentrate on flying the plane, not fixing it, until you are
on the ground. The ASSumption was the fuse is at the battery. Anywhere
else it is USELESS for protecting the wire.

Generally true, especially for a main electrical circuit, and there is an
excellent argument for always placing a fuse as near as practical to the
power source and sized to protect the wire. I would also replace the fuse
at each annual--since "everything" corrodes in the climate where I live--as
a way to assure that any failure of the fuse is indeed for a reason; because
the 2 or 3 year replacement cycle, that a reasonable person would expect,
would only assure that the replacement will be forgotten and that corrosion
will cause the fuse to heat and fail. (When I was growing up, we leared to
keep our spare household fuses in tightly sealed glass jars so that they
would remain serviceable when needed.)

There are a couple of exceptions to the "do not replace" and "do not reset"
rules--the classics being the need to retract the flaps in order to "go
around" or, on some airplanes, to lower the wheels.

Peter

A good reason to have manual flaps - and a non-electric "emergency"
wheels down mechanism.

If the fuse blew for a reason, you want to be able to get the wheels
down - WITHOUT electricity