Backup Gauge Decision

I am setting up an IFR panel in my 6A. I plan to get my IFR ticket in the 6 once built.

I have a Dynon EFIS and EMS and have equipped a backup ASI and ALT, as well as a compass. I also have a Trio AP to act as a TC backup. I bought the steam gauges as a set and have a VSI that I planned to sell. As I thought about it more, I thought maybe it would be a good backup as well. The only space left on my panel is in the upper right corner. Is it worth taking the space to put it there as a backup? I thought it might help in my training, as they will want me to do partial panel work. I could also temporarily mount it to the bottom of the panel just for training work.

I was hoping some of those with more experience than I could offer their thoughts here.

Thanks,

Larry

I think you will find that a VSI is not used as a primary intrument. Therefore not necessary to back it up. The one on your Dynon should be fine.
If for some reason you did want it, not having it in your scan would make it about useless. This goes for your other back-ups as well.
Usually partial panel means covering the Atitude Indicator and DG. Flying only by TC and compass. Still using the Altimeter and ASI. Of course this is with steam and if you loose vacuum.
To back-up an EFIS you would want direction, Atitude or TC, ASI and altitude.

My 2c

You don't mention any secondary (battery) electric power sources. If none, then you have a single point failure possible - loss of electric power leaves you with no attitude (AI or TC) info. I personally will not fly in IMC in such an aircraft.

Mark, Thanks for the guidance here. It is very helpfull.

Bob, my aircraft does not have a backup battery or alternator, but my EFIS has a built in battery backup good for a 2-3 hours.

Larry

lr172 said:

Bob, my aircraft does not have a backup battery or alternator, but my EFIS has a built in battery backup good for a 2-3 hours.

Click to expand...

My Dynon went black on me once while in flight. They fixed it promptly (even though it was technically out of warranty) and it has been rock solid since, but still something to think about.

BobTurner said:

You don't mention any secondary (battery) electric power sources. If none, then you have a single point failure possible - loss of electric power leaves you with no attitude (AI or TC) info. I personally will not fly in IMC in such an aircraft.

Click to expand...

In my opinion, in a carefully designed, carefully constructed, understood, and monitored electrical system, the battery IS the backup (resevoir) of electrical energy.

The alternator is the primary source (except prior to engine start). A second battery in a single engine aircraft only serves to divide the "resevoir" into two parts, adding complexity and keeps a proverbial single point of possible failure along with additional potential points of failure. If your goal is to have more electrical backup, consider increasing the size of the single battery, monitor it, and change it out regularly.

My opinion. Not all will agree but stated here for the reader who may not well understand DC electrical systems.

Bevan

Important Decision

In the old days, single engine IFR meant that if your alternator puked, you were still good to go with your vacuum system and a hand-held backup radio. If the vacuum failed, the TC and whiskey compass kept you upright and on course - easy.
With many of today's all electric panels (and ignitions), it's a different ballgame. First, assume that at some inopportune time, your Dynon is going to quit - either because of loss of electrical or failure of the instrument itself, and by the way, don't assume the "big" battery is going to keep powering everything for very long. IIRC, Flight Safety used to tell me to plan a 10 minute window on my 210.
You might consider a TruTrak ADI or Gemini or GRT Mini for that spare spot. They'll give you attitude and heading as well as the ability to make standard rate turns and the ADI will give vertical rate as well (not sure of the others). Most important, all have independent, backup batteries. Don't forget the handheld radio. An independent, battery backed GPS is also a good idea. The Garmins also have a "panel" page that is actually quite good.
Practice different failure scenarios, and make certain to tell ATC when the real event occurs (and it will if you fly enough).
Finally, don't hesitate to declare an emergency if you've lost an alternator or a primary piece of equipment. In the 3x's I've done so, I've never had to write a report, and being in a priority position with ATC reduces the stress level.
Terry, CFI
RV9A N323TP

Gemini PFD

Larry, I just installed a Gemini PFD in my -10. It has alt, airspeed, pitch and bank, VS and heading in one instrument. Look at it here:

http://www.trutrakflightsystems.com/products/Gemini_PFD.html

Furthermore, you can buy a backup battery pack of 2 9 volt batteries that will run it for 2 hours.

I've lost my alternator twice in 6 years.

Best,

Thanks for the comments here. I am relatively proficient with DC power and I do consider the battery as a separate system from the Alternator. I see an Alternator failure as a common scenario but do not put a complete electrical failure scenario in the same light. My Alternator can be removed from the system if it causes erratic behavior. Batteries rarely outright fail without warnings, though capacity can be greatly diminished by several variables, most of which can be addressed through maintenance and pre-flight diligence. However, if I found myself on battery only, I would plan an immediate landing as it is very tough to accurately calculate a batteries true reserve capacity at any moment in time.

What's interesting is that the single point of catastrophic failure is almost never mentioned here - The Master solenoid. A failure of this device kills all power. I can't speak to their reliability, but I know that remote automotive starter solenoids (those not mounted on the starter) were a common failure point before most OEMs moved to contactors on the starter itself.

I see the larger issue as failure of individual electrical components or circuits (shorted wires pop the breaker/fuse and you lose everything on that circuit).

I am very concerned about failure of the EFIS during IFR flight and want to back it up the best that I can. Can I assume that attitude indication, beyond the TC, is a critical element to safe IFR and therefore requiring backup? My EFIS has a backup battery, as does my 396 GPS. My Trio AP will give me TC ability. I am thinking the VSI might also be a good backup to help as well. It won't be in my scan area, but at least it is there.

Thanks again for guiding a junior aviator here.

Larry

A failure of the master solenoid is covered by including an e-bus. Endurance buses are usually designed to be powered either a relay or a redundant contactor, and are independent of the operation of the master solenoid. Check out the wiring diagrams in the Aeroelectric Connection book by Mr. Nuckolls for examples.

lr172 said:

I am very concerned about failure of the EFIS during IFR flight and want to back it up the best that I can. Can I assume that attitude indication, beyond the TC, is a critical element to safe IFR and therefore requiring backup? My EFIS has a backup battery, as does my 396 GPS. My Trio AP will give me TC ability. I am thinking the VSI might also be a good backup to help as well. It won't be in my scan area, but at least it is there.

Thanks again for guiding a junior aviator here.

Larry

Click to expand...

In my opinion, the answer to your question is 'yes'. I would strongly urge you to consider a stand alone, battery powered, attitude source. There are several available in the $1-$2K range. In my cfii experience, pilots do not practice partial panel enough, and their pp skills are weak. Worse, pilots who earn their instrument rating behind an EFIS have a very hard time going 'back' to steam gauges, and their pp skills tend to be very poor. In my opinion, in a real failure scenario, you will be so fixated on those turn coordinator bars on the Trio that having a VSI outside your scan range would be totally useless.

BobTurner said:

In my opinion, the answer to your question is 'yes'. I would strongly urge you to consider a stand alone, battery powered, attitude source. There are several available in the $1-$2K range. In my cfii experience, pilots do not practice partial panel enough, and their pp skills are weak. Worse, pilots who earn their instrument rating behind an EFIS have a very hard time going 'back' to steam gauges, and their pp skills tend to be very poor. In my opinion, in a real failure scenario, you will be so fixated on those turn coordinator bars on the Trio that having a VSI outside your scan range would be totally useless.

Click to expand...

I totally second having a secondary attitude source. It still baffles me that Cessna and Beech dont do that with there G1000 setups (Piper, and the late Mooney did)

I hate to go slightly off topic but Bob, what would you say is good ratio of partial panel to no failures flight would you say is appropriate? I for example, did 35 hours for my IRA (part 141), I flew steam, and glass (G500, and Adivine ) with the split 45/55, I flew in a partial panel situation, maybe 28 of the 35 hours. (My cross countries where in actual, and the first 2 flights I had we did not do PP) I ask because I am working to come a CFI and II.

Flyingdreamz said:

I hate to go slightly off topic but Bob, what would you say is good ratio of partial panel to no failures flight would you say is appropriate? I for example, did 35 hours for my IRA (part 141), I flew steam, and glass (G500, and Adivine ) with the split 45/55, I flew in a partial panel situation, maybe 28 of the 35 hours. (My cross countries where in actual, and the first 2 flights I had we did not do PP) I ask because I am working to come a CFI and II.

Click to expand...

There is no single answer to this - people vary a lot. Just that myself and a couple of other cfii's had noticed - to generalize - that pilots who learn on steam transition to glass quicker than vice versa. And, pilots who learn on glass often don't even see anything that looks like a turn coordinator - just some marks where the standard rate turn is. Also, since p/p is nearly always just "practiced", don't discount the psychological factor. I was once doing an IPC with a pretty good pilot, doing the initial part of an ILS p/p (conventional panel in a 172). He was under the hood (night) doing pretty well. As we flew into a thin cloud layer, I said, "Well, we're in actual now, so don't sc*** up." His performance immediately went downhill; he started fixating on the TC and altimeter and forgot to track the localizer. When I pointed that out he was still reluctant to introduce any bank at all.
I might also add that pilots who learn with a gps never seem to have a good sense of position awareness if the gps goes away, compared to those who learned without one.

I was also worried about a complete Efis failure during IFR, or a total failure of the electrical system for whatever reason.

My backup is a round altimeter and airspeed indicator (pitot static driven) with the trutrak adi in the middle. My GPS496 with its own battery powers the ground track on the adi (no wind correction required when flying the approach using the adi ground track), and the adi has its own backup battery.

Flying approaches is no harder than the efis, and the price was reasonable.

Aaron

My 2 cents FWIW:

The probabilities of having a modern well designed and installed digital EFIS fail is much lower than having a steam gauge fail. It is more probable that the EFIS will display inaccurate data instead of just completely fail. Therefore, having a backup system (EFIS or steam) in real IMC does not address the more probable situation, which indication is correct and which one will kill you?

The only way to address this is to have a third independent system (triple redundancy) as a tie-breaker. You just need to get enough information so you can decide which of the other two to use and which to ignore. The third system doesn't have to be real fancy. It can be a portable GPS, an iPad or even a smartphone with some kind of position app. So for real IMC, no matter which you select as backup, have a method to figure out which one of your systems to ignore and which one is correct.

GRT mini B. battery power backup. You can continue until the gas is gone if you need to. It will get you to any waypoint via gps and keep you upright. Check it out.