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02-18-2018, 06:27 PM
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Join Date: Apr 2017
Location: central Il
Posts: 73
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Which analogs instruments to leave in panel. GRT Sport EX install
I am considering which of the old instruments to leave in the panel. Airspeed of course, turn and bank, maybe altimeter..maybe not, if there is room. But I would also like to have a few engine gauges.
My question is, can one run the single signal wire to a resistive element analog gauge, like the fuel levels, or the oil pressure, and to the GRT EIS 4000 together? Will they read correctly?
thanks,
Don
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D. Gherardini
Central Illinois
RV9A slider 0-320 carbed
Kitfox IV (SOLD)
Luscombe 8A (SOLD)
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02-18-2018, 06:42 PM
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Join Date: May 2005
Location: X35 - Ocala, FL
Posts: 3,679
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What to leave would be determined by your mission and trust in the GRT system. As for engine gauges, I have never tried to run two systems off of one sender, but I am sure some would work and others wouldn?t. The GRT system sometimes uses pull-up voltage to convert a resistance sender into a voltage input, which would likely cause the standard gauges to be unreliable. Having the other instrument connected to the sensor should not change the GRT usability, because you can calibrate the GRT to work with just about any voltage input by adjusting the scale factor and offset to get the accurate value to display on the screen.
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Jesse Saint
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02-18-2018, 09:24 PM
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Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,297
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Quote:
Originally Posted by Jesse
What to leave would be determined by your mission and trust in the GRT system. As for engine gauges, I have never tried to run two systems off of one sender, but I am sure some would work and others wouldn?t. The GRT system sometimes uses pull-up voltage to convert a resistance sender into a voltage input, which would likely cause the standard gauges to be unreliable. Having the other instrument connected to the sensor should not change the GRT usability, because you can calibrate the GRT to work with just about any voltage input by adjusting the scale factor and offset to get the accurate value to display on the screen.
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With the exception of the oil pressure. They have this hard coded to work with the VDO sensor that they spec/supply. No scale factor/offset available.
Larry
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N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
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02-18-2018, 10:56 PM
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Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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As Jesse said, you can calibrate the GRT to read accurately if, say, the fuel level sensor is loaded by an analog gauge. But, if the analog gauge fails, then the GRT won?t read correctly either. I?d use the panel space for independent, back up flight instruments.
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02-19-2018, 01:54 AM
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Join Date: Mar 2007
Location: Sonoma County
Posts: 3,821
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Quote:
Originally Posted by N333M
I am considering which of the old instruments to leave in the panel. Airspeed of course, turn and bank, maybe altimeter..maybe not, if there is room. But I would also like to have a few engine gauges.
thanks,
Don
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I left the oil pressure gauge and sender as a back-up...... That's the one gauge that would make me get on the ground asap. The senders do have a high failure rate.
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VAF #897 Warren Moretti
2019 =VAF= Dues PAID
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02-19-2018, 06:54 AM
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Join Date: Apr 2017
Location: central Il
Posts: 73
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oil press
Gasman,
thats kinda what I was thinking, oil pressure would be nice to have backed up with analog. Did you run the single signal wire from the VDO sender to both you analog gauge AND the EIS? or leave it out of the EIS ?
Don
__________________
D. Gherardini
Central Illinois
RV9A slider 0-320 carbed
Kitfox IV (SOLD)
Luscombe 8A (SOLD)
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02-19-2018, 08:52 AM
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Join Date: Dec 2007
Location: Fredericksburg, TX
Posts: 662
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If panel room is a consideration, how about an "idiot light" for oil pressure?
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Jim Averett
RV-8
TS36 - Silver Wings
Fredericksburg, TX
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02-19-2018, 10:56 AM
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Join Date: Mar 2007
Location: Sonoma County
Posts: 3,821
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Quote:
Originally Posted by N333M
Gasman,
thats kinda what I was thinking, oil pressure would be nice to have backed up with analog. Did you run the single signal wire from the VDO sender to both you analog gauge AND the EIS? or leave it out of the EIS ?
Don
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Already had Van's OP gauge and sender mounted on top brace. Just installed a "T" and added VDO sender for MGL Xtreme.
The only sender that worked double was Van's tach sending unit works his tach and the Xtreme tach with no problem.
The back-up oil pressure gauge is not for EMS failure...... it is for sender failure which is way more common, and could cause you a lot of stress as you fly along looking for a place to land before the motor fails. A look at the back-up oil gauge would tell you the severity of the problem.
__________________
VAF #897 Warren Moretti
2019 =VAF= Dues PAID
Last edited by gasman : 02-20-2018 at 09:23 AM.
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02-19-2018, 02:43 PM
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Join Date: Jan 2005
Location: Tulsa, OK
Posts: 1,015
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I built mine with backup airspeed and altimeter (early dual dynon glass) and I also wired the oil pressure sensor to a master caution light in the panel.
I have had one instance where the glass went dark due to overheating on the way to Vettermans in South Dakota and the analogue instruments with the 796 worked out fine.
It took me a while to get used to looking at the glass as primary but I do like having the backups and I do try to keep the analogue altimeter in sync.
Some of my buddies decided on no backup analogue instruments so that they had to concentrate on the glass display and were not distracted, just different philosophies.
I do have to say that other than the one overheat situation (I now blow air around the back of the panel, RV-7 slider) the dynons have been rock solid since 2008 so reliability does not seem to be a big issue with glass cockpits.
Your call really.
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02-20-2018, 04:25 AM
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Join Date: Nov 2005
Location: Asheville, NC
Posts: 2,692
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I have zero analog engine instruments to duplicate EIS 4000 data. My thinking is that an electrical failure and loss of EIS data is one of two things: not critical since my engine is not electrically dependant or critical because I have lost other functions unrelated to engine indication. In neither case do I need analog engine instruments.
In regards to analog backup flight instruments, that is a personal choice. For VFR, none. For IFR it depends on your skill at flying partial panel. It can be done with as little as airspeed, altimeter and turn and bank. In my case, I chose airspeed, altimeter, Trutrac horizon, whiskey compass. And the answer is that they DID save my bacon once when the EFIS went TU in the soup. The event was almost a non-issue with the backups.
__________________
Bill Pendergrass
ME/AE '82
RV-7A: Flying since April 15, 2012. 850 hrs
YIO-360-M1B, mags, CS, GRT EX and WS H1s & A/P, Navworx
Unpainted, polished....kinda'... Eyeballin' vinyl really hard.
Yeah. The boss got a Silhouette Cameo 4 Xmas 2019.
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