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tonyjohnson

Well Known Member
I was inclined to include steam guages in my panel for airspeed and altimeter. I am now considering omitting those two instruments since the GRT EIS has an option of showing airspeed and altitude.

The cost of the option would be less than the two steam guages and going this route would free up valuable panel space.

Before I make that decision I wanted to post the idea here to see if there is anything that I am missing.

Is there a good reason not to use the EIS to backup the glass panel for airspeed and altitude?
 
I will have 2 grt display units and single ahrs...

if the ahrs fails then one would lose airspeed/altitude on the du's and the 4000. I chose to go with d6 with separate ahrs/mag for backup.
 
EIS

Wayne,

The EIS is not AHRS dependant according to the folks at GRT.

Of course if the EFIS and EIS get information from the same source they could not back each other up. The EIS has its own separate pitot and static connections.

I plan on using another backup as well, perhaps a D6.
 
Tony,

That's exactly what I have in my Europa, the EIS with airspeed & altimeter is backup for the GRT Sports. Works fine. EIS has it's own pitot and static ports.

BTW, EIS will come standard with airspeed in MPH. If you want KTS, tell them when you order. It's a simple internal software change for GRT.

Altitude is in feet. I'd guess they can change that to meters if wanted.

Jim Butcher
Europa XS
 
EIS

Jim,

Thanks for the heads up on the kts v mph issue. It only occurred to me recently that the EIS could serve as a backup for airspeed and altitude. That eliminates the round guages completely.

My only concern is having everything in the panel electric. Even if I had mechanical round guages for airspeed and altitude, that would not get me by in IMC without attitude indication. A non electric attitude system would require a vacuum pump with I do not see in my future.

I think this will work. That EIS is a pretty handy little unit.
 
Tony

I have a dual EFIS with EIS with alt/airspeed as backup in my -8A. Last October I had an engine (mechanical) failure at low level on a long approach. This failure caused an electrical blip for whatever reason, despite the load dump protection etc on the electrical system. The EFIS dropped out momentarily & had to reboot. In the very short time I had before hitting the trees, pushing the buttons to bring up the EIS backups was not an option so I had no airspeed info so I was trying to slow the aircraft (but not stall) by feel.Fortunately I survived the crash although the aircraft was badly damaged.

I am currently rebuilding and intend to include a 2-1/4 UMA mechanical airspeed indicator. My experience was that, if you need the backups at altitude, the EIS will be OK as you have more time, but down low & slow, having instant airspeed info might save your life - I'm thinking of an engine failure on takeoff or approach where there is a real risk of a stall/ spin.

FWIW

John Moody
 
Good point

moodyjr said:
Tony

I have a dual EFIS with EIS with alt/airspeed as backup in my -8A. Last October I had an engine (mechanical) failure at low level on a long approach. This failure caused an electrical blip for whatever reason, despite the load dump protection etc on the electrical system. The EFIS dropped out momentarily & had to reboot. In the very short time I had before hitting the trees, pushing the buttons to bring up the EIS backups was not an option so I had no airspeed info so I was trying to slow the aircraft (but not stall) by feel.Fortunately I survived the crash although the aircraft was badly damaged.

I am currently rebuilding and intend to include a 2-1/4 UMA mechanical airspeed indicator. My experience was that, if you need the backups at altitude, the EIS will be OK as you have more time, but down low & slow, having instant airspeed info might save your life - I'm thinking of an engine failure on takeoff or approach where there is a real risk of a stall/ spin.

FWIW

John Moody
Click to expand...

John,

You raise a very valid point. I am sorry to hear about your crash and the damage to your airplane. That is what I like about this site, someone here knows something about every topic that I do not know, often from experiences like yours.

I had only briefly thought about the time it takes to transition from the primary EFIS to the backup.

Did the EIS reboot as well? I wonder if I can set up a page on the EIS for AS/ALT that I can get to with one button push?
 
You can get altitude and groundspeed from your gps in an emergency. And a Lift Reserve Indicator will show you how to fly the plane.
 
Tony,

You can set up pages with the information you want (up to 2 and a third with bar graphs). My default page is airspeed, altimeter, vertical speed and fuel pressure (I have a problem I'm trying to solve). Pretty much everything else of interest is on the bottom of the EFIS. And my second EIS page is tach, MP, OP/OT.

Probably doesn't apply, but you can also ask GRT for barometric pressure in mb if needed.

Jim Butcher
Europa XS

PS I have set the limits in EIS to be the values specified by the engine manufacturer. I set limits in the EFIS a little higher, so EFIS will alarm before I reach the manufacturer's limit. Sort of provides a yellow arc warning.
 
Another option

Another option is the MGL ASX-1. I have not heard anything good about the 2 1/4" UMA Altimeter. The ASX-1 gives you an ALT and Air speed in one instrument for less money. They will also run off a 9V battery for a very long time for backup. Not sure but I believe it will serve as an encoder as well.
Tim
 
Keep in mind that if you are going to certify the plane for IFR that both altimeter sources will need to be checked per 91.411. I'm not sure of the specs on the EIS and if it was really designed with this in mind.
 
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