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  #1  
Old 02-08-2015, 04:06 PM
cccjbr6 cccjbr6 is offline
 
Join Date: Dec 2013
Location: Birmingham, AL
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Default Do I still need an independent backup AI?

I need a fresh look and an expert opinion on my new panel composition. I fly a lot of IFR and am in the middle of a complete interior redo of a 6A, including a new panel. I bought a 2 screen G3X Touch, the 305 autopilot head with blue button, and a TCM backup battery. I also got second ADAHRS in the belief that, with auto reversion, it would give me redundancy I need in case of a ADAHRS failure and avoid the expense of a backup AI. Please weigh in and tell me if this is a good plan, or if you see a hole in the plan and think I still need an independent backup AI. If the latter, why? Thanks in advance for the input!
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  #2  
Old 02-08-2015, 04:11 PM
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N941WR N941WR is offline
 
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The answer to you question is, No, you do not need (by "need", one is not required.) a backup AI. However, my recommendation is to put in a Dynon D1 or D2 Pocket Panel because they are not tied into your pitot or static systems and the internal batter will last four hours.

The internal battery is the same reason I recommend you install a good handheld GPS (not an iPad) that is constantly charged by the aircraft system. Then, if you have a total electrical failure, you can aviate and navigate.

Practicing with those two units is critical to your survival.
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Last edited by N941WR : 02-08-2015 at 06:00 PM.
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  #3  
Old 02-08-2015, 05:30 PM
WhiskeyMike WhiskeyMike is offline
 
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Location: WA State
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Quote:
Originally Posted by N941WR View Post
...I recommend you install a good handheld GPS (not an iPad) that is constantly charged by the aircraft system.
Please share your thinking as to why an IPAD or other tablet device (with built-in GPS, and running Forefligh, Garmin Pilot, etc.) is not desirable for this purpose. A tablet can be easily rigged so that it?s charged by the plane?s electrical system while in flight, so there must be some additional criteria you have in mind. Thanks in advance for your feedback ?
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  #4  
Old 02-08-2015, 05:52 PM
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FORANE FORANE is offline
 
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Location: East TN
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Quote:
Originally Posted by cccjbr6 View Post
I need a fresh look and an expert opinion on my new panel composition. I fly a lot of IFR and am in the middle of a complete interior redo of a 6A, including a new panel. I bought a 2 screen G3X Touch, the 305 autopilot head with blue button, and a TCM backup battery. I also got second ADAHRS in the belief that, with auto reversion, it would give me redundancy I need in case of a ADAHRS failure and avoid the expense of a backup AI. Please weigh in and tell me if this is a good plan, or if you see a hole in the plan and think I still need an independent backup AI. If the latter, why? Thanks in advance for the input!
I for one vote for a backup AI. I have experienced an EFIS roll inverted in IMC. I have heard from others who have experienced the same - even with a late model modern dual ADAHRS system.
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  #5  
Old 02-08-2015, 05:56 PM
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avionicsr avionicsr is offline
 
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Default Backup Attitude

Quote:
Originally Posted by cccjbr6 View Post
I need a fresh look and an expert opinion on my new panel composition. I fly a lot of IFR and am in the middle of a complete interior redo of a 6A, including a new panel. I bought a 2 screen G3X Touch, the 305 autopilot head with blue button, and a TCM backup battery. I also got second ADAHRS in the belief that, with auto reversion, it would give me redundancy I need in case of a ADAHRS failure and avoid the expense of a backup AI. Please weigh in and tell me if this is a good plan, or if you see a hole in the plan and think I still need an independent backup AI. If the latter, why? Thanks in advance for the input!
Absolutely YES, you need an independent backup Attitude, Altitude and Airspeed. We install one in every IFR panel we build. I understand this is an experimental, but we build all our panels using Part 23 guidelines, and in that application, it is required.

The reason is, even with two AHRS and an independent backup battery there is still the very, very slim potential for a common software problem to cause all displays and/or AHRS to reset. I've flown the G3X and G3X touch systems for about 300 hours total, and never had it happen, but the potential exists. That's why we use an independent Attitude, Altitude, and Airspeed. We typically use the Mid Continent MD-302 SAM or the Dynon D6. These units both have (option on the D6) an internal backup battery, and operate independently of the G3X system.

The big benefits of the MD-302 that the D6 doesn't have;
The MD302 will auto set its baro setting from the G3X and is auto dim. It is a Part 23 certified product, so it is very expensive.
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  #6  
Old 02-08-2015, 05:59 PM
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N941WR N941WR is offline
 
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Quote:
Originally Posted by WhiskeyMike View Post
Please share your thinking as to why an IPAD or other tablet device (with built-in GPS, and running Forefligh, Garmin Pilot, etc.) is not desirable for this purpose. …
First, a little background. I'm a life time IT guy and have had to support these units, Apples, Microsoft, etc.

Reasons:
1. The operating systems are unpredictable. They are designed to do more than just provide flight information and are subject to viruses. Because of this, they can run slow, crash, operate erratically. Even if you have antivirus software on them, something will get by.

2. The hardware is unpredictable. Remember, these were designed to be used in an office or home environment. They may or may not work in an airplane. Most do work, which is a good thing. However, each of our planes are different and at altitude, they could have issues due to the thin air that is supposed to provide insulation from one component to another. That's why airplanes with turbocharged engines have pressurized ignition harnesses.

3. Battery life on these things seem to die fairly quickly. So while you might think you have four hours of battery life, you might be down to an hour or less, when you really need it.

4. They are constantly changing the form factor. Thus, you design your panel and wire in brand X notepad and two years later, it goes Tango Uniform. Now you have to either buy a replacement on eBay or rewire your panel and replace the cool snap-in holder you installed for it. Oh, and by the way, the new replacement unit is a completely different size so you will have to redesign your entire panel. (Note, my Garmin 496 is also considered obsolete; however, I can buy a replacement that has been lightly used. Good luck finding a "lightly used" tablet.)

5. Can you read it in our cockpits? Some I have tired are so dim, they might as well have stayed in my flight bag.

Don't get me wrong, I like tablets but with my SkyView, D1, 496, etc. I simply don't feel the need for a "non aviation" device being pressed into service.

PS. How many people who fly with a tablet for "backup" leave it on a screen displaying an AI when they fly? Should the primary EFIS go dark or turn upside down, that would be a bad time to have to start fiddling with your tablet to bring up the appropriate screen.
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Last edited by N941WR : 02-08-2015 at 07:12 PM. Reason: Added PS.
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  #7  
Old 02-08-2015, 06:14 PM
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g3xpert g3xpert is offline
 
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Chris is already aware of our position on this, but here is a link to our previous post on this subject for reference.

Backup Instrument Posting

Thanks,
Steve
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  #8  
Old 02-09-2015, 06:53 AM
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N941WR N941WR is offline
 
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Default Positive outcome

Even with my comments above, this husband and wife team were able to land their Cessna after a total electrical failure using their iPad.

The article mentions "iPads", so maybe they had two aboard and not one.

While this happened at night, there is no indication if they were in the clouds or VFR. Two people would surly be a big help so one could fly and one could pull up the proper page on the iPad(s).

The other thing that bothers me is that they forgot to drop the gear and bellied it in.

It would be nice to hear their full story; did they have the iPad displaying the flight information or did the passenger have to bring it up, etc.

Still, I think the very simple Dynon Pocket Panel, which is designed specifically for this task, would be a better option.
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  #9  
Old 02-09-2015, 01:09 PM
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deej deej is offline
 
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Quote:
Originally Posted by N941WR View Post
PS. How many people who fly with a tablet for "backup" leave it on a screen displaying an AI when they fly?
Nearly always in my case. My iPad is the third AI on my panel, running WingX and linked to a Skyradar ADS-B receiver with the Levil AHRS unit attached.

First AI is a GRT HX with one AHRS, and second AI is a GRT Mini-X with built-in AHRS.

Plane has dual redundant electrical buses.

The chances of all three AI devices failing within the same flight is small enough for my comfort level.

-Dj
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  #10  
Old 02-09-2015, 03:31 PM
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turbo turbo is offline
 
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i also consider my TT auto pilot a back up system as long as the electrons are flowing.
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