All glass -vs- backup instruments

[RV7ator]

Everyone's talking failure. What about the Black Screen of Ambiguity?

I've experienced multiple instances of D-10As putting up a black screen, usually - but not always - from overtemp. Is it still valid info, or not? Dynon says, "Oh, it's o.k. It's signaling that some element of the guts is exceeding mfgr's spec." That is no help at all. Who you gonna call?

Why, my round gauges, of course! As others have noted, they are immensely easier to interpret than reading a digital display, plus, being stone simple (the instruments, not me!), I trust them if the EFIS disagreed.

Dynon users: vent your panel. The last black instance was during holding while awaiting vectors for an ILS. The sun, warm ambients, and low speed overheated the poor baby. Only because of the back-ups did I continue.

Two-Dynon users: consider that their Smart Buss requires configuration, something you might be loath to redo in troubled flight to get around a failure that takes down the buss.

Multiple, several redundancy is best. How much you want for whatever percentage of your time in the clag depends on your (let's be real) IFR expectations.

John Siebold

[Jordan1976]

Originally Posted by RV7ator

I've experienced multiple instances of D-10As putting up a black screen, usually - but not always - from overtemp. Is it still valid info, or not? Dynon says, "Oh, it's o.k. It's signaling that some element of the guts is exceeding mfgr's spec." That is no help at all. Who you gonna call?

This is exactly the situation Stein was talking about. We tell you when there's a failure. That's not the exclusive arena of certified units. Our theory with the black and white screen is that if all you have is the EFIS, it's better than nothing. But if you have backups, use that.

Originally Posted by RV7ator

Two-Dynon users: consider that their Smart Buss requires configuration, something you might be loath to redo in troubled flight to get around a failure that takes down the buss.

All Dynon EFIS units in a panel show local EFIS data. So if you have two Dynon EFIS units, and the buss blows up or one unit dies, the second unit just keeps on going. Sure, it throws an error, which you can acknowledge with one button. Not sure why you'd need to reconfigure in flight.

[Brantel]

Originally Posted by Jordan1976

Not sure why you'd need to reconfigure in flight.

Ian,

Can you fill us in on Dynon's thoughts about if your EFIS that dies is the DSAB master and controlling the Dynon AP and or responsible for gathering the NAV/COM/GPS data for the panel, what then? Sure with a dual EFIS system you have redundant EFIS but what about a working AP or display of your EHSI?

Right now with today's products, I see a IFR Dynon solution as follows:

1 D180, configured as the master most of the time displaying efis and HSI
1 D100 most of the time displaying engine data and info pages
Backup AS, TT ADI, and ALT
Dynon AP, dual axis AP74 or 76
HS34
NAV Source and or GPS source of your choice

If the D180 dies, you loose your primary EFIS, AP, Nav/GPS data, and engine data -- unless you can reconfigure the DSAB bus on the fly????
If the D100 dies, you loose your redundant EFIS
If both die, you loose Efis data, Nav/GPS data, engine data, AP and must resort to the steam guage backups and looking at the built in displays of the NAV/GPS gear all while hand flying the aircraft in IMC.

[N55CU]

I love my EFIS (AFS 3400) but I use my round gauge airspeed and rate of climb a lot as it only takes a glance versus a focus to get it from the EFIS
Randy Utsey
N55CU
RV-7
Charlotte, N.C.

[stu517]

A very important point was made here. Most of the current GA panels do not have enough cooling to support the increased amount of electronics being used. These all in one EFIS's generally put out a ton of heat and are sensitive as well. I fried two experimental EFIS's myself. Once I was able to adequately move air behind the panel things worked a ton better. BTW, this applies to certified planes as well. One of the "tricks" with Cirrus owners is to add a fan behind the panel when an annual is done. Best $$ spent. A good way to tell is to touh the metal casings of your avionics while on a long cross country. If they are hot to the touch you need more cooling. Any of the parts houses have them well under $200.

[dynonsupport]

Brian,

We've never sold the AP as having redundant sources. Buy a AP from any other company, and if it dies, it dies, just like we do. So think of it more this way:

D180 = ADAHRS, HSI, AP
D100 = ADAHRS

We think this is a very usable solution. As you say, you still have the displays for the navigational stuff right on the GPS display, so in the failure of the D180, you can still stay level and navigate.

Given that many people in the past configured this way:
D180, or D100+D120
Other AP

You still have the same amount of redundancy you always had, except you actually have a backup ADAHRS, so you're even better off, and you've saved some money. We think that two of our EFIS units, with one acting as the autopilot in your system (in other words, you consider one primarily as your autopilot, and the other as your primary set of flight instruments), will prove to be more reliable than the AP function as any standalone AP.

If you are really concerned about a backup HSI, you can wire a switch to the backup D100 that will shunt the serial data to it in the case of a failure. Then your backup D100 is still a EFIS and HSI. It is never an AP without ground reconfiguration.

[Brantel]

Thanks Dynon,

I just want to be 100% sure that I understand the limitations of the Dynon solution since my panel is 99.9% going to be based on the current Dynon products and the new AP .

That being said, I know all systems have some sort of limitations, it is just important to know what they are.

As long as I know the limitations, I can plan for the surprises that get thrown my way...

[SteinAir]

Originally Posted by dynonsupport

Brian,

....Two EFIS units in the system are just as reliable on the AP function as any standalone AP.......

Come on now, let's try to keep the rhetoric down here and stick with the facts. What exactly are you basing the above statement of fact on? How many fleet hours of reliability data do you have on your AP in customer installations? At the moment, I was of the understanding that with the exception of beta testers, there is a sum-total of zero production customer installed units in the air?! Am I wrong here?

Just trying to keep the facts straight here. There is a big difference between historically accurate reliability data and marketing/sales rhetoric.

Cheers,
Stein

[dynonsupport]

You're right Stein. We've amended the post to reflect our full opinion more clearly .

I think you're splitting hairs though. The point is that from a system-level perspective, thinking of one of two of your Dynon EFISs exclusively as your Autopilot gives you the same sort of robustness as a standalone autopilot gives you. Ie - if your "autopilot" EFIS fails, you lose your autopilot. If your standalone autopilot fails, you lose your autopilot.

Our Autopilot is fundamentally our EFIS, so there is no reason to expect that adding the Autopilot feature will result in a product that is less reliable than the identical hardware that we've shipped thousands of times.

The servos are admittedly unproven in the market, but we've built them to be as reliable as other Dynon products, if that's worth anything. We do have thousands of hours between lab and flight testing on them, though.

[wv4i]

>>>If you only have two identical EFISes in your panel (and nothing else, not even a handheld GPS)...when one is leaning left and one is leaning right - which one is correct?<<<

The above question has been raised several times in this thread. The answer is what's the heading doing, assuming the ball is in the center? .

To expand further, if one pitch is up, the other down, what's the altitude doing? VSI? Airspeed?

Basics.

Now if these readings are all coming from the same source, then that really could be a problem. As devices become interconnected, at what point are they really no longer separate sourced? Are you sure that they are really separate sourced? And, as a practical matter, separate sources will make indentifying and repairing of the offending unit/sensor much simpler.

For purposes of this discussion, the 737-800 has dual EFIS, dual Nav displays, redundant sources whose failure will cause an auto transfer in some cases, and a multifunction electric LCD backup attitude indicator with a/s, alt, loc/gs, integral. The latter will run from the battery bus, and uses pitot/static info independent from the primary EFISes. All in all, a fairly typical setup in the newer Boeings, i.e. 737/757/767/777.

But we're not operating airliners or spacecraft here. And most will not be routinely taking SINGLE engine airplanes into hard IFR, i.e. ice, trw, wx to mins, etc., I hope? Been there, done that, and don't recommend it. And it IS possible for anything to fail, no matter how well thought out and sophisticated. Where does reasonable prudence and planning suffice? Years ago, we had an MD-11 that apparently had two of it's three 3D orientation systems fail, and those systems are/were tied into a host of systems that generated envelope protection with automated responses of various modes, i.e. autothrottle auto engage, horns/bells/lights, etc. Suffice to say that without the true professionals at the controls, this would have been a widely publicized event. But this WAS an airline operation.

More recently, we had a 757 get down to battery power only. Apparently multiple "independent" failures appear to be the cause, but the investigation is ongoing. To expand, this means standby attitude gyro only, as well as a loss of numerous other systems that really make your job tough. The pilots literally both had their hands full in the flare. This WAS an airline operation also.

If electronics, integration and design of components is your interest, and/or time/money's no object, that's great. But, we need to not lose sight of the ball here, i.e. what most of us really need for a safe operation. As alluded to in the quote, the GPS generated flight "instruments" page in the handheld Garmins should be enough to keep you out of a jam, in the failure modes considered by this thread, as well as settle the different indications issue that may be raised by competing EFISes. If not, should YOU really be flying IFR, VFR at night, etc.?

Back to just being a reader, and thanks for all the useful info this site provides.