Glass, IFR and Backup

macrafic · #1 08-24-2006, 10:37 AM

I have been reading the posts about this topic for several weeks. There seems to be a general sense that steam guages (airspeed, AI and altimeter) are required as a backup to an EFIS for IFR. I'm not sure I'm understanding this. Could I get some comments on this?

In particular, could I get some comments on how the following configuration meets, or doesn't meet, your idea of an IFR platform? Dynon FlightDEK-D180 on the main buss, Dynon EFIS-D10A on the essential buss, Bob Nuckolls dual alternator and single batter "all electric on a budget", at least one E-mag and one P-mag (if not two P-mags), True-Trak Digiflight II (2-axis auto pilot), and 2 independent AOAs (Dynon and ACS).

The weakest point in this configuration seems to be a single point of failure for EMS information. While the D180 can feed its display to the D10A, should the D180 display fail, I suppose it is possible for the D180 to fail in such a way as to be unable to feed the D10A anything. In that case, I would have an EFIS (D10A), but no engine instruments (since these units can not share probes).

If the D180 fails. leaving me with the D10A, I still have all the instrumentation (and much more) that I would have if I had backup steam guages instead.

DGlaeser · #2 08-24-2006, 12:01 PM

I believe many of us are using steam guages to back up a single EFIS unit. If you are going to have dual independent EFISs, that provides redundancy. Some may argue that if a software problem causes a failure, it might affect both units if they are running the same s/w. You get to decide if this is a real risk

Your autopilot is actually a third way to keep the sunny side up.

If you follow Bob N's philosophy, power everything essential from the Ebus. Why lose your primary EFIS when you go to the Ebus? Switch off the other one to save battery if that is an issue. Same for Nav radios.

In an emergency, engine info is not essential IMHO - no backup required.

frankh · #3 08-24-2006, 12:48 PM

Here's mine

AI and alt steam guage
Dynon EFIS (battery backed up)
Pictorial pilot (also gives visual representaion of the horizon)
GNS 430
ICOM A200
GTX 327

Two electric fuel pumps (no mechanical pump)
SD10 backup alt (just runs fuel pumps, ICOM and Transponder, if the main alt dies)
Emag/Pmag

Frank

Pirkka · #4 08-25-2006, 05:14 AM

Quote:

Originally Posted by DGlaeser

In an emergency, engine info is not essential IMHO - no backup required.

I would say same thing. It's unlikely that all problems will come at once. If you lose your Dynon, the propability of engine failure is smaller but exists. I think that it's better stay in ground rather than trying to backup everything.

And the another way: how much you really use engine meters? You just check quickly that engines are on green but how much closer you keep track on velocity, altitude or heading. If you would have no gauges at all what would be first meters that you would select? So they should work whatever happens also when something fails.

How ofter the pitot is blocked by bee or something? Just wondering is there reasong to have discrete pitot for electric/stream systems?

N395V · #5 08-25-2006, 07:13 AM

I have a friend with 2 Dynons who was VFR on top when lightning struck"nearby" both units went black.

I have 1 pitot and 2 BMA Efis's and a mud dauber disabled both my systems (shame on me for an inadequate preflight)

IMHO if you go IFR you need 1 steam guage gyro and a separate pitot /pitot static system as backup.

Also if your nav system is integral to the EFIi then a backup portable GPS.

Captain_John · #6 08-25-2006, 07:39 AM

Something to think about:

Everyone nowadays (including you, myself and certified builders) are installing backup instrumentation to any electric system. It is just the generally accepted "thing" to do.

I think this has something to do with the traditionally unreliable nature and pessimistic view of everything electrical/avaition.

Rapco has made a MINT on replacing pumps for years and we all know the unrelaible nature of the tradional AI, but we accept it because it is mechanical and we understand it's limitations.

Just a guess into the future here, but I say that when pilots treat their electrical systems with the knowledge and operate it with the same deftness that we do our steam system, we will see people dropping the steam backups and going totally with panel displays.

We, as a group are not ready to make that step now, being paranoid pilots... but there are a few bold souls out there and I am not going to chastise them for it!

CJ

P.S. Maca, I think you are on the right track!

MTBehnke · #7 08-25-2006, 08:07 AM

Backups are great, but regardless of whether your talking redundant glass, glass with steam backup, or all steam, you also need a way to decide which one's telling the truth. I'd be careful to not assume an EFIS failure is going to be obvious by a blank or locked up screen. A software bug in your EFIS could be showing level flight while your backup is showing a steep bank turn. Which one you going to follow?

aadamson · #8 08-25-2006, 08:35 AM

There is no *requirement* for backup steam gauges in an IFR experimental panel. There is currently in the certified world however. So that has carried over to the airplanes that we build. I would suggest that some DAR's may be more comfortable with seeing a panel with those 3 mentioned gauges, but again, it isnt a requirement.

I also agree fully with the failure concepts listed above. I advocate greatly, training, including partial panel with a hybrid panel. There are ways that you can introduce mach failures into a hybrid system that you should really learn to recognize and adjust your scan and flying based upon.

You'll have to develop each of these flight environments once you have your panel and set behind it for awhile, but it should be included in your currency training.

IMHO that is

prkaye · #9 08-25-2006, 08:49 AM

How big a deal is it to upgrade your panel to IFR later on? I was thinking of getting my plane done as a VFR machine, for cost and time (and because I'm not IFR certified). But if I think I may someday want to go IFR, should I make the panel that way right at the start, or is it not too big a deal to open it up and add the required instruments later?

DGlaeser · #10 08-25-2006, 09:52 AM

Quote:

Originally Posted by prkaye

How big a deal is it to upgrade your panel to IFR later on? I was thinking of getting my plane done as a VFR machine, for cost and time (and because I'm not IFR certified). But if I think I may someday want to go IFR, should I make the panel that way right at the start, or is it not too big a deal to open it up and add the required instruments later?

The big problem is predicting exactly what you will want in your IFR panel. The electronic world changes quite rapidly, and by the time you're ready to upgrade you'll probably have choices that don't exist now. My suggestion (worth what you paid for it :-) - when you're ready to upgrade, get a new IP and configure it with what you want - including re-use of stuff you already have.
The one thing I do suggest is to be sure your fuseblocks (primary and Ebus - assuming you're doing an AeroElectric inspired system) have some empty slots for future expansion.