On Mar 27, 1:30*am, wrote:
The battery Contactor on *MOST *GA *airplanes *is
'powered' ( grounded) * by ONE wire!

This is true.

When the Battery *contactor circuit opens / fails *you WILL *loose
the alternator *because the battery acts as a capacitor to *smooth out
DC *power fluctuations, spikes, *and * AC ripple : *the alternator
field current *will go wild and the overvoltage regulator will cut
out. * With out field current you have no Alternator!

That depends on how the alternator controller works, and what kind of
alternator you have.

For example, many of the later Raytheon/Beech airplanes use a self-
exciting alternator. You can literally start the engine, turn off the
master, and you maintain power to the bus from alternator only. Of
course if you turn off the field, you can't get the alternator back
without battery power. Seen this on the Duchess.

Then there are the generators. They don't need the battery at all,
assuming a decent load on the system and a decent controller. The
Zeftronics systems are like that - lose battery or contactor, and you
maintain generator power.

The stock Piper and Cessna systems - not so nice... If you're going
to fly IFR, choose your system wisely - and understand how it works.

*In IFR You have HAD IT! * * NO DC power!

Really? Why? Most planes flying IFR these days have a handheld GPS
for backup nav, and have primary (attitude and heading) gyros driven
by vacuum/pressure pumps, which are engine driven. Of course since
the engines have magneto ignition, they'll keep spinning - and driving
the gyros.

The all-electric airplanes have backup power systems, as well they
should, and do not rely on a single bus.

Seconds to live, *....... because of ONE........ get it!!! ONE
common point failure of an essential IFR *system!

Um, no - not seconds to live. Even without the handheld GPS for
navigation, you have primary gyros, compass, altimeter, engine power,
and your flashlight (if it's night) - and can probably fly to an area
of VFR or, last ditch, make a letdown over water or flat land. You
probably have hours to live and try to resolve the problem. A
handheld GPS and batteries make a cheap backup and allow you to shoot
most VOR (and all NDB) approaches to better accuracy than the
underlying approach, making the electrical failure no big deal. Now
if you lose the engine as well... But now we're talking two
simultaneous unrelated point failures.

For that matter, why not start with the engine? That's where you
really have the problem, assuming you only have one. And the pistons
are all linked to ONE crankshaft, which is housed in ONE case,
supplied by ONE oil pump, fed through ONE fuel line, etc. Fail any of
those and the engine will stop making power long before you can get it
on the ground in IFR conditions.

There are risks to flying IFR, but the particular risk you mention is
quite manageable and not the death sentence you make it out to be. In
other words - you don't know what you are talking about.

Michael