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whifof100ll

Well Known Member
I'm trying to guage the importance of an EFIS that still provides adequate attitude information given the failure of pitot static system or GPS. I want light IFR capability and want to install an EFIS using the Tru Trak ADI pilot II as not only an autopilot, but an attitude backup. I've seen many post on aiding requirements for the different EFIS's, but not for the Tru Track ADI. The manual states attitude works without GPS, but does anybody know how it works with a loss of pitot static?

Finishing this project is getting expensive, and I'm considering a D180 because of price, but it concerns me that if the pitot tube freezes, attitude informaiton is unreliable. I know that they state you can install reduntant pitot/static connections, but that seems like a lot of complexity. Also, they both might freeze, correct? This would be less of a concern if the Tru Trak ADI still worked as an attitude instrument without external aid.

MGL stuff looks great, but Odyssey is too large for my panel and Voyager might be too late for me. I need delivery in the March 08.

Advanced Flight Systems looks good. My only concern is what happens if there is a power glitch in flight. The manual state that you lose attitude for 2 minutes. Thats a long time in IMC. The manual also states that it needs to sit still for 2 minutes. Can it recover from a power loss or watchdog failure in flight or do you lose the attitude for the remaining flight duration? I'm not sure if it is any different than GRT. What is the likelyhood of a power loss or system reboot with a backup battery? How long has this product been out and how relaible had it been?

GRT looks like a great answer, but a bit pricey for me.
 
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Hummmmm

No 2 ways about it.....

You NEED an attitude indicator for either primary or secondary to trust whilst in IMC.
 
Tons of people are using the TT ADI as a backup.

To get DG info, you must have a working GPS connected to the ADI, even with loss of GPS it will still give bank angle.

It must have static to show pitch because the pitch indication is a fake indication based on the vertical speed trend stabilized by some gyro info & algorithms. Easy to provide alternate static source.

Bottom line is that yes it is not an additude indicator but it seems it would function just fine as a substitute if you needed it.

I asked TT some questions a while back related to this:

****************
Hi Brian,
If you were upside down flying straight and level, what would be the indication on the ADI? In other words if you were inverted and the vertical speed is not changing, would it show a level pitch attitude? How about the bank angle indication, would it tell you you need to roll over? The ADI will show straight and level flight. If you stay inverted long enough for the ADI to return to level, it will work just as if you were not inverted only backwards.
Also, in the event you loose the GPS signal, how does this impact the units accuracy? The ADI Pilot's backup mode is a bank angle mode. It will give you degrees of bank either left or right. The DG in the ADI is a gyro enhanced GPS ground track, without the GPS signal, you will not have a ground track indication.
What happens if you stay in a standard rate turn for an extended period? Will the unit eventually normalize to that turn and then show straight and level even though you are turning? The ADI will not normalize to a turn. As long as you are still turning, it will still show you your bank angle. The gyros used are rate gyros, attitude/position gyros, as long as there is a rate of change, it will indicate so.

I hope this helps answer your questions. If you have any others, please let me know. Thanks!


Lucas Massengale
Customer Service Manager
TruTrak Flight Systems
479-751-0250
479-770-2919 (Direct Line)
www.trutrakap.com​
 
Just as an alternative, my panel has the BMA EFIS One SV display and I use the BMA Autopilot. My backup ADI is a Tru Trak with the internal GPS, so it is unlikely that I will lose both GPSs at once unless we go to war. The addition of the internal GPS to the ADI wasn't much and did not complicate the installation except for routing an extra GPS antenna.
 
ADI..

The ADI requires static only. The static is provided by a "vent" in the unit.
There doesn't have to be a connection to the pitot static system of the plane. My ADI was installed with 3 wires: power, ground and internal light.

I got mine with the internal gps so it shows ground track on the face of the unit. Of course, it also has a battery backup option. If it's the only thing working in your panel, you'll still have bank/pitch, vertical speed and ground track.

John
 
whifof100ll said:
Advanced Flight Systems looks good. My only concern is what happens if there is a power glitch in flight. The manual state that you lose attitude for 2 minutes. Thats a long time in IMC. The manual also states that it needs to sit still for 2 minutes. Can it recover from a power loss or watchdog failure in flight or do you lose the attitude for the remaining flight duration? I'm not sure if it is any different than GRT. What is the likelyhood of a power loss or system reboot with a backup battery? How long has this product been out and how relaible had it been?
Click to expand...

THE AF-3500 MANUAL DOES NOT STATE THAT YOU WILL LOSE ATTITUDE FOR 2 MINUTES. I have never been able to lose the AHRS in my RV-4. I bet I could make you sick before we lost it :)
So what is the real truth?

1. On Power-Up, the Aircraft should stand still for approximately 40 seconds. We actually recommend that the EFIS be wired to the master switch and that you have it on before you start the engine. As long as you have the internal lithium battery the EFIS and AHRS will NOT reboot due to low voltage on engine start. The difference between our Crossbow AHRS and the Certified Crossbow 500 AHRS is that ours has a special board that lets it run on the lower lithium battery voltage.

2. If you exceed around 250 degrees per second for more than a couple of seconds the AHRS will detect an over range and a RED X will be displayed. If this happens, you will need to keep the pitch and roll under 4 degrees per second for 45 to 60 seconds.

3. The Crossbow 500 AHRS has been around for years and with thousands of flight hours. Advanced Flight Systems has been producing Engine Monitors and AOA systems for over 8 years. We have been flying the EFIS for around two years and there are a lot of EFIS systems flying. Every Glasair Sportsman that is built in the Two-Weeks-to-Taxi program gets at least one EFIS and these planes tend to fly pretty quick and get a lot of hours on them.

4. A “Power Glitch” will do nothing. We have a rechargeable internal Lithium battery that will power the EFIS and AHRS for over an hour when fully charged.


Sincerely,

Rob Hickman
Advanced Flight Systems
 
Sorry for the misquote.

N401RH said:
THE AF-3500 MANUAL DOES NOT STATE THAT YOU WILL LOSE ATTITUDE FOR 2 MINUTES. I have never been able to lose the AHRS in my RV-4. I bet I could make you sick before we lost it :)
So what is the real truth?

1. On Power-Up, the Aircraft should stand still for approximately 40 seconds. We actually recommend that the EFIS be wired to the master switch and that you have it on before you start the engine. As long as you have the internal lithium battery the EFIS and AHRS will NOT reboot due to low voltage on engine start. The difference between our Crossbow AHRS and the Certified Crossbow 500 AHRS is that ours has a special board that lets it run on the lower lithium battery voltage.

Rob Hickman
Advanced Flight Systems
Click to expand...

Thanks for the reply Rob and for straightening me out on the power up requirement. The reason that I'm probing so much on your EFIS, is that I have read the manual and from what I see, I really like the product and I'm seriously considering buying one. Thank you for addressing my concerns.

The manual states that unit should sit still until the red x disappears after power up. I don't know where I got the two minutes from and I apologize for the misquote. My concern is that if there was a reset due to software or hardware instability would the unit come back at all. If the statistical probability of this happening in flight is low, that is great. Knowing how many flying units are out there and how long you have been making EFIS units can be benificial in addressing these concerns. The other item of interest is knowing if there was a way of in flight recovery. Could I pull a breaker and reset the unit while flying straight and level on the backup ADI and expect it to recover?
 
GRT EFIS

Hi whifof100ll,

As you may have read in earlier posts the AHRS from GRT does not require pitot/static or GPS to provide attitude data.

The GRT Sport, our entry level EFIS, has two power inputs so loss of power is unlikely if separate power sources are used. The GRT Sport can also drive the ADI laterally to heading, GPS flight plan and synthetic approach.

If power is cycled in the air the AHRS goes into an air-align mode and returns attitude data as soon as possible. This may take a few seconds or up to 2 minutes.

All EFI(s) are computers, require power, etc. GRT works hard to provide the best possible solution and though rare, failures of one kind or another do occur. For this reason build your panel with the most primary system redundancy you can. The ADI is a good primary system instrument you will use often and can be a system backup as well.

The GRT Horizon system has more primary system redundancy built-in than the GRT Sport. This includes three power inputs, reversionary/redundant display capabilities and a dual AHRS with integrity monitoring option to name a few.

Regards,

Carlos Fernandez
GRT Avionics
 
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whifof100ll said:
The other item of interest is knowing if there was a way of in flight recovery. Could I pull a breaker and reset the unit while flying straight and level on the backup ADI and expect it to recover?
Click to expand...

Yes, the Crossbow AHRS will align as long as the pitch and roll is kept below 4 deg per second for 45-60 seconds.

You will be able to see our AF-3500EE around the Airshow Circuit this summer performing in a SU-29 :)

Rob Hickman
Advanced Flight Systems
 
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GRT Sport HS pricing vs Dynon D180

The price difference between the D180 and our Sport HS is not that different.

Dynon D180, bright screen, wiring harness, and sensors for 4 cyl with fuelflow is $4290.00

GRT Sport HS, wiring harness, and sensors for 4 cyl with fuel flow is $4975.00

Advanced Flight AF-3400EE with same options is $6035.00


With the addition of HITS, auto pilot integration, traffic from Zaon or a Garmin 330 among other features over the Dynon helps make up for the small increase in price.

For $400.00 you can add an internal GPS and moving map.

As far as backups for IFR, you really need 3 sources of attitude. The minimum being EFIS, Trutrak ADI, and an Autopilot. If you have the ADI be the autopilot that is only 2 sources. You can not determine the bad source with only 2, only that they disagree and now without the third source you have to use GPS ground track or compass/VSI/AS to try and figure it all out.

You can substitute DG, Turn coordinator, Electric AI, for the ADI or autopilot.

The regs do not state it that way, you could just use the EFIS and meet the regs. Rather be safe than legal here.

Todd Stehouwer
Design Engineer / Owner
Grand Rapids Technologies, Inc.
RV6 Restoration almost complete
RV10 Quickbuild
 
todds said:
As far as backups for IFR, you really need 3 sources of attitude. The minimum being EFIS, Trutrak ADI, and an Autopilot. If you have the ADI be the autopilot that is only 2 sources. You can not determine the bad source with only 2, only that they disagree and now without the third source you have to use GPS ground track or compass/VSI/AS to try and figure it all out.
Click to expand...

3 sources of attitude?

1960 and 70s vintage spam cans don't have that and are still perfectly fine for IFR. In my -7A, I backup my BMA Efis Lite G3 with an Airspeed Indicator, Altimeter, compass and a TruTrak ADI Pilot I.

I'd much rather have the TruTrak than an electric turn coordinator.
 
3 sources of attitude

I should have said 3 gyro instruments as in a six pack.

I too would rather the Trutrak ADI instead of a turn coordinator, and that is exactly what I am using in my RV6 and probably my RV10.

An AHRS has the functionality of a six pack, but you can not cross check the DG, TC and AI like you can in a six pack.


Todd Stehouwer
Design Engineer / Owner
Grand Rapids Technologies, Inc.
RV6 Restoration almost complete
RV10 Quickbuild
 
Vintage spam can

alcladrv said:
3 sources of attitude?

1960 and 70s vintage spam cans don't have that and are still perfectly fine for IFR. In my -7A, I backup my BMA Efis Lite G3 with an Airspeed Indicator, Altimeter, compass and a TruTrak ADI Pilot I.

I'd much rather have the TruTrak than an electric turn coordinator.
Click to expand...

I own and regularly fly an IFR approved vintage spam can. I've learned my lesson the hard way that vacuum pumps that have internals that need to be oil free and suck agaist a engine oil seal is a certain failure over time. I've had the vac pump fail twice on me in IMC. It won't happen again.
 
Sincere thanks

Rob, Carlos and Todd

Thanks very much for straightening me out on several misconseptions and on the advice.

It illustrates that the experimental world really has spectacular choices these days.

You guys are all very persuasive!

I look forward to making a decision and implementing it soon.

Regards,
 
Dual AHRS

Most, well all actually, of the corporate equipment that I have the privelage of flying operate with 2 independent AHRS/ADCs. Is that an option with these types of EFIS setups?

Thanks.
 
Geronimo4497 said:
Most, well all actually, of the corporate equipment that I have the privelage of flying operate with 2 independent AHRS/ADCs. Is that an option with these types of EFIS setups?

Thanks.
Click to expand...

Yes, the GRT Horizon has this capability.

CarlosF@grtavionics said:
The GRT Horizon system has more primary system redundancy built-in than the GRT Sport. This includes three power inputs, reversionary/redundant display capabilities and a dual AHRS with integrity monitoring option to name a few.

Regards,

Carlos Fernandez
GRT Avionics
Click to expand...

Carlos Fernandez
GRT Avionics
 
whifof100ll said:
I own and regularly fly an IFR approved vintage spam can. I've learned my lesson the hard way that vacuum pumps that have internals that need to be oil free and suck agaist a engine oil seal is a certain failure over time. I've had the vac pump fail twice on me in IMC. It won't happen again.
Click to expand...
Ah, yes, as one person put it "The vacuum pump, aka the Time Bomb". No thanks. We're shopping for an IFR airplane and and we are avoiding vac pump airplanes as much as possible.

I'll admit that we're looking at certified airplanes too (my partner in the airplane isn't sold on Experimentals - yet), but the inability to use affordable EFIS, even as backup, is frustrating. Australia at least allows non-certified instruments to be installed as long as they are not replacing non-required instruments. A Dynon D10A would be a great supplement in a spam can trainer. FAA, are you listening?

And when you mean "it won't happen again", remember that some pilots will experience vacuum pump failure in IMC only once :eek:

TODR
 
Geronimo4497 said:
Most, well all actually, of the corporate equipment that I have the privelage of flying operate with 2 independent AHRS/ADCs. Is that an option with these types of EFIS setups?
Thanks.
Click to expand...

Yes,
All of our systems have Ethernet communications between the screens. If you want a dual AHRS system you should install an EE (EFIS and Engine) and EF (EFIS), this will give you a dual AHRS system.

We currently send all EFIS, Engine, Navigation, and ARINC 429 data between the screens using Ethernet.

We are close to sending Weather and Traffic between screens, we are currently testing the Garmin GTX330 and Zaon with the latest map software.

Rob Hickman
Advanced Flight Systems
 
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