What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Glass panel question

RonRV8

Member
What is your opinion of a glass panel with a primary EFIS and a backup EFIS, but without an air speed indicator or altimeter for backup, or for that matter, any analog round gauge at all? In other words, do you think it is safe to have a panel without a simple old direct reading ASI for backup?

Ron
 
What is your opinion of a --------
Ron

Can%20of%20worms.jpg


How pilot types here???
 
I suppose the simplest way would be to use a backup EFIS that has internal battery backup power, and preferably from a different manufacturer than the primary. I'm having trouble thinking of a down side to that, if you don't consider EMP a big issue.

I didn't search but I'm betting this has been discussed many times before.
 
Like all things aviation "it depends."

What is your mission? How much hard IFR will you be doing? Do you trust the system you're installing? Battery backup? Planning on night flight?

For me personally, I wanted all the above. G3X with battry back up, Dynon D6 for back up as well. YMMV. No "steam" dials anywhere on the panel.

If you wanted a third backup, most of the handheld GPS units have some varient of a "six pack" they'll display if all else fails.
 
My first panel had a D100 w/ backup battery. Next to that I installed an airspeed indicator and altimeter. For backup nave purposes I had a Garmin 496 in the panel.

Later, when I upgraded the panel with a 10" SkyView I pulled out the steam gauges and never looked back. However, the 496 is still in there and I have a Dynon D1 Pocket Panel.

Keep in mind, if you install steam gauges that use the same static and pitot system as your EFIS, then you really don't have redundancy as a problem with either of those two lines would impact both the EFIS and Steam gauge.

To get true redundancy you need to install a second pitot system and either a second static system or a way to open the one you have.
 
You need a backup

If you fly 'hard' IFR, you need a backup. The questions becomes what type of backup are you comfortable with. Paul Dye described a very robust electrical architecture, so he has backup electrical capability. If you add an independent backup EFIS with its own backup battery, you probably have it all covered. I fly professionally behind such a system.

For my airplane, I added a round ASI and altimeter, because if things go bad, I want to look at a round guage and not have to think about how to get power to my electronics. I also don't intend to fly more than occasional IFR in the RV, (other than time under the hood to remain current).

DD
 
I think you will find that many serious IFR efis panels now use a second brand efis as a back-up instead of steam. Most are using the Tru-Trak Gemini or Dydnon D-6. I like the D-6 with an internal back-up battery since it does not require a GPS input from another source. The Tru-Trak does. My D-6 will be completely independant.
 
For actual IFR you "should" have 3 separate attitude sources from at least 2 different manufacturers. Two of them "should" be connected to the Pitot/Static sources for airspeed and altitude. The different manufacturer is in case one manufacturer has a bug in their software that affects all their products.

Now, these can be all glass as long as the glass is not supsceptible to electrical failure. I have a Dynon Skyview, a Dynon D6 and a Garmnin AERA as my 3 attitude sources. All of them with 2hr+ of battery backup. No Steam guages in my panel.

I also agree with the post about at least an alternate static source for real IFR, but that is no different for glass as it is for steam.

BTW You can no longer buy some new production aircraft (like the Cessna TTx seen below as an example) with steam gauges of any kind. Even their backup is glass.
img-SE-avionics-TTX.ashx



My 2 cents.
:cool:
 
Last edited:
One more thing to consider... A Second Alternator...on my Flying RV-7A I have 2-G3X displays that have a TCW battery backup, I have a Dynon D10A as my standby EFIS (with internal battery backup)... Because I never intended to have a vacuum system, I installed a second alternator on my vacuum pump pad. My RV is IFR certified with WAAS GPS only, no VOR/ILS, etc... With 2 alternators and 2 battery backups, and the main battery, my confidence level is high that if my systems become problematic (whether VFR or IFR) I can land my RV safely.

Good luck with your decision.

Victor
 
About 5 minutes after you posted this, Stein sent a progress pic of my panel. D6 as back up.

vq34o0.jpg
 
I don't see it as any different than having a "single-source" failure point such as a single pitot tube. You can have as many displays of the data as you want (within reason to accommodate display failure modes) but you are still subject to a grasshopper being in the wrong place at the wrong time during your takeoff roll.

Myself, I have a fully glass panel, dual 10" Skyviews with battery backup, plus an MGL EXtreme Mini-EFIS as a Plan B EFIS - but they are all still tied into one single pitot tube. For attitude, I've got the Dynon and the MGL ADAHRS boxes, with dual alternators and battery backup on the Dynon.
 
I think you have to consider your own personal view of risk taking, and what you are prepared to pay to mitigate those risks. Pitot static instruments are very reliable, as are good quality electric gyros. All uncertified electronics has an unknown reliability and unpredictable failure modes - but most are much more reliable than vacuum gyro instruments in your average spamcan (vac pump is the limiting factor). Most people building a $100K airplane can afford an ASI, altimeter and electric AI - do you feel you need that insurance?

I think you should assess the risks you might be taking (in the context of single engine IFR) with your choice of primary instruments, think carefully about your appetite to accept those risks, and therefore how you want to mitigate them (or not).

Pete
 
I was and still am a firm believer of steam gauges for back up. My reason for that is ,
- It is simple and reliable
- Requires no electrical component/backup in case of electrical melt down
- No learning curve to stay proficient for IFR use whereas you will need to stay proficient in learning/retaining usage of both system.
 
Myself, I have a fully glass panel, dual 10" Skyviews with battery backup, plus an MGL EXtreme Mini-EFIS as a Plan B EFIS - but they are all still tied into one single pitot tube.

Which is no different than if you had steam gauges instead of glass. The question is regarding glass versus steam instruments, not about 100% redundant IFR capable aircraft. These are extremely few, even in the certificated single engine GA world.

:cool:
 
Last edited:
I was and still am a firm believer of steam gauges for back up. My reason for that is ,
- It is simple and reliable
- Requires no electrical component/backup in case of electrical melt down
- No learning curve to stay proficient for IFR use whereas you will need to stay proficient in learning/retaining usage of both system.

What is your non-electrical, reliable source of attitude information?
 
What is your non-electrical, reliable source of attitude information?

Bob,
You got me there :)

I have a TT ADI, which of course is electric but short of putting a vacuum pump, this was the best I could come up with, but with a battery backup of course.


DSC_6147 by bavafa1, on Flickr
 
Last edited:
We think it's safe. We make this stuff for a living, see the failure rates, and know the issues. Yet, this is our airplane, fully IMC equipped. No dissimilar systems, no steam gauges. We would not say that you should fly in IMC with NO backups, but in my opinion, pretty much any backup is reasonable given the failure rates of a modern EFIS system.

I realize it's not for everyone, but if you are willing to fly IMC with a single engine, a single pilot, a single pitot, single com, etc, yet worried about crazy redundancy in your panel, you may not be focusing on the real and likely failure points.

The advantage of a fully integrated system like this as well is the reduction in workload when everything is working normally. No cross-checking stuff yourself, no setting two barometers, huge screens full of information, no "partial panel" when a screen does go out. You need to balance the use of a system in IFR for the 99.99% of the time it's working well with your capability if it ever does go out. Most accidents are not equipment failures, they are human failures, and anything that reduces that is a huge mark in the win column.

Oh, and we have 3 screens because we can and we use them for testing, not for redundancy. 2 screens are as good as 3 in my book.

4osh.png


--Ian Jordan
Dynon Avionics
 
Last edited:
VFR flying

Gotta post for us VFR pilots, with no plans to take our VFR suited RV's into IMC.

I have dual screen G3X's. One AHRS. One pitot (unheated). One magnetometer. One transponder. Two comms (convenience). No steam gauges.

What if I lose my AHRS/pitot/both screens?!?!? Well, then I fly to a convenient airport and land. Period. No drama. I may land a bit faster without AS, but I can pick a long (i.e. anything >2500 ft) runway to do so. The airframe tells me my speed with enough granularity to land (and I ain't no test pilot). To find the airport I pull out my 296, or look at my iPad with foreflight. Both will also give me ground speed and GPS altitude as well.

I've thought about this a lot. I can't understand the need for steam AS and ALT backups for VFR flight, equipped as I am otherwise. Open to other opinions though. Convince me...
 
I don't think anyone suggested that backup flight instruments were needed for VFR operations.

For those with a TT ADI: this may look like a conventional AI but it is hardly a 'steam gauge'. Inside there are no spinning gyros. It uses the same accelerometers as the efis's do.
 
Add this topic to the primer war list. It's a debate with no correct answer, only personal opinions based upon individuals own experience levels and concerns.

Is it prudent to have a backup device in case your EFIS fails? Certainly if you are IFR. Should it be from a different manaufacturer? If IFR, the answer would be yes. It mitigates the very small risk should there be a software issue that renders the EFIS non-operational. You don't want a software bug rendering all displays inoperable.

If you primarily fly VFR, then then answer is whatever it takes to make your spouse sleep better at night. It's not necessary, but it's not required. Like Ian mentioned, there are other items to be concerned with if you're discussing risk management.

Should it be steam or another EFIS? Personal choice.

My choice was a Trutrak Gemini. My decision was made to keep the user interfaces similiar to minimize think time issues in an emergency. Is my decision good for anyone else? Maybe, but that isn't may call.

Some folks have flown behind steam gauges for long enough, that those are more intuitive for them. There is nothing wrong with that decision either.

There is no correct answer. The best we can do is share the decisions we made for ourselves and the logic we used that led us to that conclusion. Then let others determine if that same decision tree works for them and their mission.

This is simple risk management as penguin Pete has stated. How to mitigate and which risks to accept are going to be different for each of us.
 
I realize it's not for everyone, but if you are willing to fly IMC with a single engine, a single pilot, a single pitot, single com, etc, yet worried about crazy redundancy in your panel, you may not be focusing on the real and likely failure points.

Exactly how I feel about the debate. The only way to eliminate ALL possible failures while flying, is not to fly at all.

This is my panel which I fly "soft" (no thunderstorms) IFR in.
76-TheNewInstrumentPanel_zps4a8a81ff.jpg


:cool:
 
Last edited:
I have some analog, for a different reason

Here is mine, just shipped from Stein. I have the steam gauges mainly for flying competition acro, I felt it would be much easier and quicker to get the info I need on airspeed and altitude from analog gauges when flying competition, your attention should be mostly outside the airplane during this activity. I will fly acro from the right seat, hence the steam gauges on the right. I will fly x-country from the left seat, I was originally going to fly from the right seat, then I pictured trying to turn knobs and use a touch screen in turbulence with my left hand (I am right-handed). So I put a starter button on both side as well. The dock is for my trusty 396, and I will have an iPad and iPhone as well, hence the USB power slots. With 5 GPS's on board, VOR/ILS, two ADHRS, battery backups, I feel I have much more reliability and redundancy than I did all the hours I flew single engine IFR in spam cans. It doesn't have the reliability of a twin turboprop with dual pitot tubes and dual alternators, but I don't plan on long cross countries over or into low IFR conditions, more just punching through layers. It will be very fun keeping up my proficiency in this plane, though, so I am expecting many practice approaches to minimums!

Going to and from competitions will sure be much more luxurious in this plane, and a whole lot easier and less stressful when I can file IFR to do it! Maybe I will start a new trend among lazy old acro pilots (like me) who don't want to work so hard anymore! :)

P9042162.jpg
 
I think you have to consider your own personal view of risk taking, and what you are prepared to pay to mitigate those risks. ... Most people building a $100K airplane can afford an ASI, altimeter and electric AI - do you feel you need that insurance?

... you should assess the risks you might be taking (in the context of single engine IFR) with your choice of primary instruments, think carefully about your appetite to accept those risks, and therefore how you want to mitigate them (or not).

Pete

Pete nailed it. Couldn't have said it better.
 
Steam versus electronic backup

I'm not sure why backup instrumentation has to be steam driven. Lockheed Martin don't care for it in the F22, nor do numerous other manufacturers. I mean, sure, if you have no backup electrical source well maybe that makes sense. But it depends what failures you want to mitigate against.

If you really want true instrumentation redundancy then you'll need dual pitot, dual static, anti-iced, dual independent power supplies connected to your primary and backup systems. How far do you want to go?

Any IFR (notwithstanding legal requirements) I would have primary attitude/speed/altitude, then a secondary attitude/speed/altitude with an independent power supply. I have no problem with same brand names of prim & sec EFIS. Pitot of course would be anti-iced/heated. Steam-driven? Well, if you really want to.

VFR...meh. Whatever. :)
 
My first panel never had any steam or AHRS backups but it was VFR only...

c7vuu.jpg


My redo does not have any steam either:


This one currently has three and soon to be four sets of gyro's to keep the greasy side down. It has 6 GPS's full time and has 9 sometimes when I have my Iphone, Ipad and 796 in the cockpit. It has a main battery that can run everything for over 30 minutes and a backup battery that can run critical components for over an hour.

All of this sound like overkill but in reality it happened without much thought given to redundancy. The modern components just lean that way when all put together as a system when you use stuff that is intended to work together.

On my first flight, it took about a minute to get in sync with only having digital tapes for the critical stuff. I have never looked back. The modern EFIS systems have really good altitude and speed tapes and they are easy to interpret. If a screen fails, I have two more with automatic failover capabilities.

Its a good time to be an avionics geek and an EAB builder/owner/pilot!
 
it's safe

I initially had some concern when I realized I couldn't fit any of my steam gauges in my (in progress) dual screen G3X panel upgrade, thinking I wanted some backups if my power went out. Then I remembered all my gyros were electrical anyway, and haven't thought twice about it since. I live in a very high mountain valley, and spend a lot of time flying over 14.5k mountains at night - I will feel safer with my new synthetic vision screens (each of which is a backup for ALL your instrumentation) then I ever did with my steam gauges.
 
Big G meets heavy G

Most RVs do not have enough power / thrust for sustained excessive g loading of the available EFIS offerings however.... Please see you tube "Miss Demeanour Biggin Hill from the cockpit". Hawker Hunter. Retro fitted with a TSO G600 or perhaps a G500.

Take off at 14:00. See how a few minutes of sustained G loading in a holding pattern does at 18:50 . Then its down for the count at about 24 minutes when the G really start piling on at show time.

Note worthy is that every time the G loading has compressed the pilot far enough to view the 2 spinning gyro attitude indicators, they both display an accurate horizon, long after the EFIS AHRS has quit for the day.

YMMV
 
Last edited:
I haven't experienced many failures, but one was a clogged pitot tube. Seems prudent, in a redundant panel, to have two pitot tubes.

Dave
 
Note worthy is that every time the G loading has compressed the pilot far enough to view the 2 spinning gyro attitude indicators, they both display an accurate horizon, long after the EFIS AHRS has quit for the day.

YMMV

Just a question, how often do those spinning gyro's have to be replaced? Does this type of flying impact their MTBF?

As for the video you mentioned, I would bet that there is something wrong with that installation/callibration/AHRS. The failures shown were not typical of a modern glass system. I have tested sustained 2-2.5 g turns (what that guy was doing while holding) for over 10 minutes with my G3X and it never missed a beat. I played with a mini EFIS at Osh for a long time trying my best to tumble it and no matter how hard I tried, I could not get it to saturate and tumble.

I would bet that if the issues are corrected that are causing the AHRS to fail with the sustained 2-3g turns, that the reliability will improve during the high performance show part of the flying.
 
Last edited:
Backup nav radio?

I've seen a number of panels that have three EFISs but only one certified nav radio (usually a 430 or 430W). What's the plan if the 430 goes dark and you have to fly an approach?
 
I've seen a number of panels that have three EFISs but only one certified nav radio (usually a 430 or 430W). What's the plan if the 430 goes dark and you have to fly an approach?

The same plan as if you had steam gauges and your 430 goes dark. In that situation it doesn't matter if your display is EFIS or Steam. Now my panel has a Nav 2 receiver (VOR/LOC/GS) for that possibility. AND it makes the 30day VOR check a lot easier to do.
:cool:
 
I've seen a number of panels that have three EFISs but only one certified nav radio (usually a 430 or 430W). What's the plan if the 430 goes dark and you have to fly an approach?

Some options in no particular order:

Radar approach
Backup SP400 or other handheld is an option
Use the approach features built into a VFR GPS/EFIS. Yes I would in an emergency like that. I would use whatever I had.
Go someplace else that is VFR

The good news is that these boxes don't appear to die very often in flight.
 
The same plan as if you had steam gauges and your 430 goes dark. In that situation it doesn't matter if your display is EFIS or Steam. Now my panel has a Nav 2 receiver (VOR/LOC/GS) for that possibility. AND it makes the 30day VOR check a lot easier to do.
:cool:

True it's the same as if you had steam gauges, but most such traditional panels have two navcoms.
 
Probably so, but if you're going to install three EFISs because one may fail it seems surprising to assume that the nav box will not fail.

In my case I did not install three screens for the sole purpose of screen redundancy. That is just a bonus but not the primary reason.

I think the biggest reason that most people don't install two TSO'd navigators or a separate NAV solution is cost. After they purchase the primary navigator they are broke! :p
 
I think the biggest reason that most people don't install two TSO'd navigators or a separate NAV solution is cost. After they purchase the primary navigator they are broke! :p

Well that certainly makes sense. I've seen some panels that I suspect must cost more than my whole plane!
 
In my case I did not install three screens for the sole purpose of screen redundancy. That is just a bonus but not the primary reason.

I think the biggest reason that most people don't install two TSO'd navigators or a separate NAV solution is cost. After they purchase the primary navigator they are broke! :p

Being TSO'd only applies to GPS navigators in order to legally file and fly /G. If it is a common VOR/LOC/GS receiver it does not have to be TSO'd, especially as an emergency backup. Personally I have a VAL INS429 as my NAV2. Now, you can still find and use a working NARCO NAV-121 or NARCO NAV-122 as a NAV2 especially if you are going to fly actual IFR.
:cool:
 
For emergency use a battery powered, portable GPS works just fine for non-precision approaches, assuming it has an aviation database.

(I have separate gps (420W) and vor/ils (SL30) installed; battery powered gps (iPad) and battery powered hand held nav/com (Sportys) for emergency use).
 
Being TSO'd only applies to GPS navigators in order to legally file and fly /G. If it is a common VOR/LOC/GS receiver it does not have to be TSO'd, especially as an emergency backup. Personally I have a VAL INS429 as my NAV2. Now, you can still find and use a working NARCO NAV-121 or NARCO NAV-122 as a NAV2 especially if you are going to fly actual IFR.
:cool:

All true but the Alan was referring to panels with /G TSO'd Navigators.
 
Last edited:
Mmm.... Well this thread has drifted a bit from the OPs post that was completely about EFIS PFD flight data vs steam flight data. The thread has drifted to navigation redundancy. If you are in a death spiral, knowing where you are going to hit is merely a convenience.

I put in steam backups but I see the case for alternate brand glass. It still gives me the willies. I can't help it. I'm kinda' like Bob Axsom where he talks about root physics mechanisms earlier in this thread.
 
I was lucky enough to be a beta tester for Dynon when they were developing their D1 Pocket Panel.

That thing is rock solid and will keep you upright if your EFIS or steam gauges go out. With its four plus hour battery, GPS derived AS & altitude, artificial horizon, and more it is the ideal backup solution.

Even better is you can add Velcro and stick it under your glair shield so you don't have to look across the panel and risk disorientation.

Add a hand held GPS with an internal battery and you can get down.

As for the radio, remember, airplanes fly just fine without them.
 
All this talk about electronics not being "root physics" makes me wonder why my diploma says "Electrical Engineering and Applied Physics." ;)

--Ian Jordan
Dynon Avionics
 
I'm still trying to figure out how root physics differs from normal physics.

Funny how people worry about the reliability of modern electronics but have no problem with a steam gauge containing a conglomeration of levers, aneroids, gears, diaphragms, pinions, and hairsprings. ;)
 
I'm still trying to figure out how root physics differs from normal physics.

Maybe because semiconductors are based on quantum physics?

Funny how people worry about the reliability of modern electronics but have no problem with a steam gauge containing a conglomeration of levers, aneroids, gears, diaphragms, pinions, and hairsprings. ;)

Yes, it's a miracle they work at all.
:cool:
 
It is because it is all done with smoke and mirrors and we all know if the smoke gets out or a mirror gets broken the thing stops working.
 
All this talk about electronics not being "root physics" makes me wonder why my diploma says "Electrical Engineering and Applied Physics." ;)

--Ian Jordan
Dynon Avionics

All the real stuff happened over at the Mechanical and Aerospace building.

Anybody that claimed they understood Maxwells equations was lying. :D (Navier-Stokes is a piece of cake however :rolleyes: )

But seriously, I did use the wrong terms my post. I know electrical devices are based in "root principles". It does not change the fact that I do not trust them as much as a mechanical device. Don't confuse me with the facts. :)
 
Last edited:
Back
Top