Panel and Backup Questions

While waiting for the fuselage, I am playing with the panel and what I want to put in it. I already ordered a Lycoming IO-390 with dual P-Mags. I am going to put in Dual G3X Touch screens and also Vertical Power (VP-X Pro). So the question is, I can't decide how to back this up. I do plan on flying IFR, but only when necessary. I am a first time builder and I even know less about avionics, etc., so please be nice. What is the best advice? Dual alternators, dual battery, dual ADAHRS, backup EFIS of a different type? Considering weight and price, please give me your recommendations. I have learned so much from the experienced builders from VAF and I am thanking you in advance.

Your going to get a lot of varied opinions. Remember that the only opinion that counts is yours. It sounds like you given quite a bit of thought on the subject. Define you mission, then determine what you'll do if that device fails. Then do the same for all the devices in you panel. This should give you an idea what you need to do.

I have dual alternators and dual batteries. Some will argue that dual batteries is overkill with dual alternators. I wanted to be able to isolate one bus from the other.

The problem with dual EFIS and ADAHRs is that if one fails, which one do you believe is correct. That's why I also have a third source from a different vendor. I not only wanted a tie breaker, but if a software issue should arise, I wanted something that ran different source code.

This was the fun part of the build for me. Have fun designing your dream panel!

Bob

As Bob said, you'll hear everything from "bare minimum required per FAR 91.205" to "two engines". Personally, my minimum for even a brief exposure to IMC would be an independent (including its own battery) EFIS, like a Dynon D-6 or GRT Mini; plus a battery operated GPS for navigation.

You will never eliminate the risk entirely; do what you need to do to make it acceptably low to you, and your passengers.

Take a look at the Dynon D1 and D2 Pocket Panels. They have good battery life and don't require any connection to your pitot or static system.

For navigation backup, get a panel dock and add a Garmin handheld GPS of your choice.

Ditto on most of the above. For my backup I have an autopilot capable of sustaining level flight without input from other avionics, and a 396. I fly my 4 in IMC quite a bit.

Additionally, the more different systems you install, the more there is to master. I am a fan of having simple, easy backup systems that are easy to train for failure scenarios with.

Good luck!

Icarus said:

Ditto on most of the above. For my backup I have an autopilot capable of sustaining level flight without input from other avionics, and a 396.

Good luck!

Click to expand...

Does your autopilot work if the main battery and alternator fail? e.g., a direct short on the main buss bar.

Wait to buy

Not sure what your time frame is on the fuselage an its completion but you've got considerable time. Wait as long as possible for your panel. Things change so rapidly that there may be significant changes or newer stuff out there when you're closer reality.

Just my thoughts but the forum is full of people that probably bought too soon. Whether they will admit it or not is another matter.

Darwin makes a great point that I forgot to mention. Early in the build I was laid off for a period. So,I took advantage of the time and developed a complete schematic and a very detailed workbook.

Two years later, I change ninety percent of the gear in the original panel design.

Things will change, not only the technology, but your mind will too.

Wait until 6-9 months before the end of the build to make your final decisions on the panel.

Instead of dual G3X's, you could consider the second unit could be a completely independent of all other systems unit with built in battery.

there are a couple of phases to the backup analysis.

• Mission, as stated before.

• Preliminary configuration.

• Analysis of failure. (fail any system. Will that one system failure kill you?).

• Revision of configuration to eliminate or accommodate the failure.

In regards to buying early or not. I fit in the class Darwin mentioned. I bought avionics before the motor for a couple of reasons. I would do it that way again although I am in the minority opinion on this board about it.

1. I could spread out the purchases over time so I could manage it out of the checkbook rather than savings and it allowed time to save for the motor.
2. When the engine purchase was made, my firewall penetrations were COMPLETE, with all the connections hanging there ready to hook up. Hanging the motor was like putting a motor on a factory built plane. Hang it and hook it up. This minimized the storage time for the motor which in my view was more valuable than the avionics.

Panel

Thanks everyone for the great advice. Yes, I am going to wait as long as I can to purchase, but was working on my avionics and electrical education while I wait on the fuselage. I am sure technology will keep improving and so will the avionics. Today was my original ship date for the fuselage, so I am in mourning. I've never been into drugs, but this stuff has to be more addicting than crack. There is so much to learn and I appreciate the education. Back to waiting...

No, my A/P is not on a separate battery/bus, and no my system isn't insulated against solar flares and weapons grade EM pulses.

My point was simple, very few accidents (CFIT) stem from glass panel failures. Most stem from poor decision making and/or unfamiliarity with systems/procedures. The more systems...the more constant training one must do to master all of the reversionary modes and emergency letdowns.

MY solution is simplicity backed with constant and simple training. Your solution may have more blinky lights, it will just require more effort to remain emergency proficient.

More devices, more probability of failure, more weight, more cost...

Consider building a single, light, reliable battery/bus/alternator system. Back it up with one or more of the portable devices for nav and attitude.

Problem with multi, dual redundancy - if anything fails - are you going to turn back or divert? Most who are concerned with having dual devices would not proceed with one failed. So get ready to have more diverted trips because you have increased your probability of experiencing one of these failures with every added device.

with capability comes complexity

our plane has a dual screen EFIS system fed by 2 GPS units plus an SL30 for VOR/ILS. Very capable and reliable. For backup:

You can not beat the Garmin 696/796, awesome backup tool with its own battery (plus able to show weather and traffic).
Our plane has the BC SD8 backup alternator and battery. Nice to have two sources of electrons.
Ipad with foreflight, completely separate from the aircraft electrical system. Awesome list of capabilities and growing every day.
TT autopilot will fly the plane on a heading and altitude with no other devices working (just needs power)