On Thu, 26 Oct 2006 11:14:44 GMT, "Neil Gould"
wrote in
:

Recently, Larry Dighera posted:

On 25 Oct 2006 18:28:57 -0700, "cjcampbell"
wrote in
.com:


Larry Dighera wrote:


I don't need a scientific degree in logic to understand even
without reading the POH that when the screen goes black, all those
nifty things which were on that very screen before are, well, not
available anymore.

True. But I wasn't aware that the autopilot wouldn't even work as a
wing leveler.


Whatever made you think that it would? The autopilot is obviously
electrical.


In the scenario I have in mind (Mr. Rhine's recent ferry trip), he
didn't lose electrical power. The G1000 went into infinite re-boot
mode.

I'm not so sure that this is a "mode" of the G1000, but that's beside the
point.

If Mr. Rhine's narrative is to be believed, there is empirical
evidence that supports such a "failure" mode, and that may be part of
the point I'm pursuing.

For example, in the event the G1000 becomes inoperative (let's say its
circuit breaker won't reset), without affecting the function of the
balance of the aircraft's electrical system, why couldn't the (most
likely) electrically driven AI be fitted with an encoder to drive the
autopilot (sans Nav capability, of course)? If I were in IMC, and
lost the G1000's communications, navigational, flight and systems
instrumentation, I'd surely appreciate the opportunity the autopilot
would afford, to read some emergency procedures, and tend to duties
with which I'd probably be saturated initially. That might be
difficult to accomplish expediently without the autopilot while flying
partial panel IFR. (Could you still squawk 7600?)

I guess it boils down to an aversion to "having all the eggs in a
single basket." To me, that raises a red hazard flag calling the
systems engineering forethought into question. Perhaps I don't know
enough about the particulars of the system, or the emergency
procedures in place, but it seems obvious that something as small as a
stray alpha particle or static discharge could precipitate a sudden
and massive loss of functionality.

Suddenly you'd be piloting a Jenny in the clouds with *only* a map and
compass. :-) This exciting, twenty-first century technological
advancement in avionics seems to come with a "time machine" capable of
transporting a pilot back to the nineteenth century days of
barnstorming and flying the mail.

If faced with that condition, I would have simply shut the thing
off so as not to be annoyed and distracted by the "reboot light show".
Afterwards, one just follows POH procedure for total G1000 failure mode.
Not a big deal.

That is a reasonable response. Apparently the G1000 would operate for
a while between re-boots, so Mr. Rhine may have had some motivation to
view those glowing screens for a few miles at a time while over the
chilly Atlantic.

Besides, pilots flew with "only ASI, AI, VSI, Alt. and magnetic
compass steam gages" for decades, so what's the big deal.

They usually had some sort of fuel gage.


The fuel gauges in Skyhawks have been electrical for decades. We have
been losing them in power failures for more than thirty years.

True. It was a poor choice for an example of the massive loss of
instrument display that occurs when the G1000 goes down in a C-172.
The HondaJet must surely have some instrumentation hidden behind a
panel someplace, or the FAA wouldn't certify it, right?

Despite the electrical system being operational, the fuel gages are
part of the non-functional G1000.

I always consider the fuel gauges as feeding questionable information.
They are often not very accurate in the range between "full" and "zero".
Also, the same fuel levels can result in different gauge readings from one
plane to another.

All very true, and if a needle is bouncing, there's a good chance that
gage's tank's got fuel in it.

A clock is a much better "fuel gauge", as long as the
fuel system is intact.

I wonder if there's a mechanical clock or if the clock's integrated in
the G1000 too?

If there's a fuel leak, then either above scenario can bite you just as badly.

Right.

And if you've got fuel coming out the overflow/vent, and aux-tank fuel
system modifications, you might value those gages more than normal to
help diagnose the cause of a malfunction.