FADEC = complex

Morgans wrote:
Planes (except from what someone wrote about the Theilert, which I have a hard
time understanding, and am unable to confirm) still have a mechanical connection
with the engine.

I think that's too strict a statement. Some do as a backup and some
don't. Most appear to use a throttle position sensor like cars do (and
boy do I hate the analog ones with a simple wiper arm over a resistive
field... you're just asking for uncommanded power excursions in a car,
much less in reported cases of failure on helicopters with that kind of
system).

Others exclusively use a mechanical connection, which of course means
it's NOT a FADEC system at all.

The Continental has every injector controlled by two computers. The spark is
controlled by a different computer for each cylinder, with each of the two plugs
in the cylinder having a different computer. There are dual sensors of each
type of sensor. There are two electrical systems for each set of computers.
Everything is protected from lightning strikes, and the associated surges.

All things considered, there is more protection and redundancy in the aircraft
FADEC than the aircraft without the FADEC.

That's a totally invalid conclusion. An engine without FADEC doesn't
require all those dual systems, because it can't fail in the same way.
For a traditional engine to fail in a way unique to its systems, both
magnetos must stop working. Does anyone here think that's a common
situation?

For FADEC to fail, all you have to lose is electrical power, or a pair
of sensors (ever have the crank position sensors or their wires fail on
your car engine? I have. In several cars. It's not at all uncommon.)

Worse, a software failure can screw up your FADEC. Google a bit, and
you'll easily find examples of oh, say, Airbus code failures that
stopped engines mid-flight. Or the example of the Chinook helicopters
where a FADEC code review found over 480 code anomalies in the first
15% of program lines.

Btw, did you see this Thielert AD because of engine stoppage due to
software?

http://www.casa.gov.au/airworth/airw...IELERT-003.pdf

You can be assured that before an engine is certified with a FADEC, that the FAA
has considered every possible failure mode, and has made sure that the engine
will keep running, if at all possible.

Now you sound a lot like what you claim is wrong with Mx. Prove that
statement if you can. I don't believe the FAA does any such thing. It
simply gives the manufacturer a set of guidelines. From what I've
read, there's no requirement beyond dual power systems to ensure that
the engine keeps running, only that a failure doesn't disentegrate the
engine or prop.

ANY aircraft engine can stop running. They are made to keep running, if at all
possible. An aircraft engine with a totally mechanical carb or injection with
magnetos has more possibility of stopping, than a FADEC engine, I would guess.
I do not have any facts to back up that statement.
Notice how I put it out front, when I was only guessing, or speculating? If a
certain other poster had stated his assumptions like that, there would not have
been all of the "personal" attacks.

Given that criterion, you should've put out front that you were
guessing on most of your posting. It's clear you're NOT an engineer,
despite the fact that you and newps seem to have Googled up some info
overnight. Does that mean we should all resort to personal attacks at
you?

Kev

Thomas Borchert wrote:
Mxsmanic,
If you fly a plane manually, and a problem with control surfaces
develops and progresses, you'll find it more and more difficult to
fly. If you have an autopilot, you'll notice nothing until the
problems with the control surfaces reach a point that is beyond the
ability of the autopilot to compensate.

Utter, complete nonsense.

How can you claim Mxsmanic doesn't know what he's talking about, when
you yourself make such obviously incorrect statements?

Do you remember, for easy example, the commuter flight that dove in a
few years ago because it iced up to the point of tail-stalling, but
their autopilot hid that condition until it was turned off?

Kev

In article ,
says...


So the guy who is not motivated enough to find out on his own what a magenta
shaded area on a sectional means is now a designer of FADEC's?

The lie was put to this when he demonstrated (at the beginning of this thread)
that he didn't have a clue what is meant by "complex" or why that is of
interest to pilots.

GF

Walt,

I know we don't have an argument :-)

Does this really make a difference?


Well, the FAA requires redundancy, Ford doesn't.

--
Thomas Borchert (EDDH)

Jose,

How so? Oversimplified, to be sure, but "utter nonsense"? Nonsense!

I snipped the true nonsense part, the "spiral down to death" thing.

One of the things pilots must be aware of when using an autopilot for
example is trim.

Not with all autopilots. Some S-Tecs don't use trim.

--
Thomas Borchert (EDDH)

Thomas Borchert wrote:
Kev,
1) FADEC designs can have a bypass system, mechanical or not. But this
is expensive redundancy, and cars / GA planes don't usually have it.

Plain wrong. The Thielert, for example, not only has backup-power, but
also two Engine Control Units comparing each other. One ECU is the
"bypass" for the other. If those all fail, yes, you have a problem.

Read more carefully. I said GA _usually_ doesn't have the redundancy.
The Thielert does, but at a price. There's a good reason why GA
owners haven't jumped towards retrofitting with FADEC... it's hard to
justify $10,000 for better starting and economy.

That's the case with all failing back-ups. Increased risk compared to
non-FADEC engines? Show me how, show me where!

I didn't bring up increased risk. Obviously the EEC equipped engine
(FADEC or not) will have better economy, starting, and so forth, that
we've all come to love and expect in cars. Statistically speaking,
it's probably true that electronics theoretically have less risk.

But judging from my forty years' experience with automobile engines
(including having rebuilt my share as a youth), I would have to agree
with Mxsmanic that you're far more likely to have a sudden unannounced
failure with a FADEC system than with a traditional mechanical system,
where some warning (slack in the controls, engine output not up to par,
etc) is often forthcoming.

Of course, neither setup can prevent a sudden cylinder failure, or oil
pump, or fuel pump, or vacuum pump, or other such mechanical
commonality.

2) FADEC computers will fail with power loss, and that almost always
means engine stoppage.

Which is why there are back-ups in certified GA FADECS.

Yes, backup battery or alternator. The latter is a better choice I'd
think, since a battery only gives about an hour. If it's belt-driven
though, it seems risky to me.

There are many cases of this happening on airliners.

Just one related NTSB or ASRS report, please.

Just Google for "fadec failure history".

You can also see this happen with your own car, more and
more of which are FADEC these days... i.e. no mechanical throttle
linkage, just a throttle position sensor.

Cars are completely different, they are not certified.

Sorry, gotta agree with Mx again. I've done certified government
software, and it's generally a meaningless certification.

Kev

Kev,

Does anyone here think that's a common
situation?


Well, compared to what? FADEC failures? Yes, until you provide me with
numbers to the contrary, I do think they are equally common (which is
to say, very uncommon). Think of the dual Bendix magnetoes here.

--
Thomas Borchert (EDDH)

Kev,

Read more carefully. I said GA _usually_ doesn't have the redundancy.
The Thielert does, but at a price.

The redudancy is not the reason for the price of the Thielert. And under many
operating circumstances, a Thielert conversion might be cheaper than a normal
engine.

Just one related NTSB or ASRS report, please.

Just Google for "fadec failure history".

I did. No joy. Now you do it.

Sorry, gotta agree with Mx again. I've done certified government
software, and it's generally a meaningless certification.

A "government certification" is not an FAA certification.

--
Thomas Borchert (EDDH)

Kev wrote:
There's a good reason why GA
owners haven't jumped towards retrofitting with FADEC... it's hard to
justify $10,000 for better starting and economy.

Not that hard. A big bore Continental like mine will easily save an
average of 2 gph. That's a $10,200 savings over the 1700 hour life of
my 520 at $3 a gallon.

Kev wrote:



Yes, backup battery or alternator. The latter is a better choice I'd
think, since a battery only gives about an hour. If it's belt-driven
though, it seems risky to me.

You would get a dedicated battery for the FADEC, the ones I've seen are
smaller than a motorcycle battery and this would easily outlast your
fuel supply at any power setting that keeps you aloft. It draws very
little currrent.