VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.






VAF on Twitter:
@VansAirForceNet


Go Back   VAF Forums > Model Specific > RV-12/RV-12iS
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 01-18-2023, 11:40 PM
kshunz kshunz is offline
 
Join Date: Jan 2023
Location: Seattle, WA
Posts: 3
Default RV-12iS EMS and generator operation

We have two new RV-12iS aircraft coming soon to our flying club. I've never flown one, but as the Ops Officer I need to understand them.

I believe there's a switch on the upper console marked "EMS Backup Battery". As far as I can tell, there's no backup battery; this switch allows the main aircraft battery to power the ignition in case both generators fail. Do I have that right?

If Generator A fails, Generator B powers the EMS but the rest of the airplane is running off the main battery. If the battery voltage drops too low to run the fuel pumps, the engine stops. Correct?

The POH advises to turn off non-essential electrical equipment with a generator failure. I wonder if that ought to include one of the fuel pumps.

If both generators fail, I assume the engine stops until you flip on the EMS Backup Battery switch and then restart the engine.

These will each have a G3X display, and I understand there's an actual backup battery for that. But if aircraft power is lost, the fuel pumps stop and the engine stops. So this backup battery is just to keep the EFIS running during the final glide? This makes me wonder whether there's something I don't understand.

Can someone who knows this system confirm that I'm on the right track?
Reply With Quote
  #2  
Old 01-19-2023, 04:48 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,457
Default

Scott, you have a very good understanding of the operation of the Rotax 912iS operation. Everything that you wrote is correct. The chances of both alternators and the aircraft battery failing on a single flight are remote. Pilots should never takeoff with a weak battery. The battery should be load tested annually. http://forums.matronics.com/viewtopi...r=asc&start=20
__________________
Joe Gores
RV-12 Flying
Reply With Quote
  #3  
Old 01-19-2023, 06:06 AM
thiggins thiggins is online now
 
Join Date: Mar 2020
Location: Saluda,NC
Posts: 195
Default Worth watching

https://youtu.be/xo2JTX2Rwk8

Heres a great explanation, with wonderful graphics.
Yes, a 915, but I believe this is identical to the 912.
__________________
Donation 2023 paid
ASEL INST COMM Tail-wheeler
RV-12iS builder (Empennage complete, Wings complete!, Fuselage well under way !, finish kit ordered, Garmin avionics ordered, engine ordered, shop out of order )
Got a hangar, and moved some large pieces in!
https://eaabuilderslog.org/?blproject&proj=7buPHH99v
Reply With Quote
  #4  
Old 01-19-2023, 08:55 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 2,855
Default

Quote:
Originally Posted by Mich48041 View Post
Pilots should never takeoff with a weak battery. The battery should be load tested annually.
I installed new PC680 last year (RV-12 w/ 912ULS) and it lasted about 8 months. On the day it failed, engine started as usual followed by 30-minute flight with shutdown. No cranking for restart. Odyssey replaced battery under warranty. Everything looks good....until it doesn't....
__________________
-
Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 830

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father - CFI) - USAAF 1st Lt. Captain B-17H
Reply With Quote
  #5  
Old 01-19-2023, 10:33 AM
kshunz kshunz is offline
 
Join Date: Jan 2023
Location: Seattle, WA
Posts: 3
Default

Quote:
Originally Posted by thiggins View Post
https://youtu.be/xo2JTX2Rwk8

Heres a great explanation, with wonderful graphics.
Yes, a 915, but I believe this is identical to the 912.
Great video, and if it applies to the 912iS then I think it points out an error in my understanding. It shows the fuel pumps being supplied directly by the generators. With a failure of either generator, you might run the main battery dead but the pumps (and engine) will continue to run. The POH procedures and the EFIS backup battery provision make a lot more sense with this insight.

Thanks!
Scott
Reply With Quote
  #6  
Old 01-19-2023, 11:47 AM
sparkcrafter sparkcrafter is offline
 
Join Date: Jun 2014
Location: Battle Ground, WA
Posts: 57
Default

There is a backup battery. See the attached schematic.

-Jerald
Attached Thumbnails
Click image for larger version

Name:	DEBEEC48-8857-4FF6-AD3C-E2171C479030.jpeg
Views:	61
Size:	555.8 KB
ID:	37090  
Reply With Quote
  #7  
Old 01-19-2023, 12:58 PM
rcarsey's Avatar
rcarsey rcarsey is offline
 
Join Date: Jul 2012
Location: North Brunswick, NJ
Posts: 406
Default

You seem to have a good understanding of how the system works.

Quote:
Originally Posted by kshunz View Post
If Generator A fails, Generator B powers the EMS but the rest of the airplane is running off the main battery. If the battery voltage drops too low to run the fuel pumps, the engine stops. Correct?
The pumps are not powered how you'd probably normally think. Think of them as part of the ECU/EMS. They would continue to be powered by Gen B.

Quote:
Originally Posted by kshunz View Post
The POH advises to turn off non-essential electrical equipment with a generator failure. I wonder if that ought to include one of the fuel pumps.
Definitely leave both running. They're being powered by Gen B (which is now dedicated to running the engine only at this point, after Gen A died). Everything else in the aircraft is now running off battery -- so kill things like landing lights, nav lights, USB power, etc. as safety permits.

Quote:
Originally Posted by kshunz View Post
If both generators fail, I assume the engine stops until you flip on the EMS Backup Battery switch and then restart the engine.
Exactly. Only at this point, would I even think about turning off one fuel pump -- and that would be in some ridiculous circumstance where the next suitable field is far away and I'm trying to conserve as much power as possible to make sure I can get there.

Quote:
Originally Posted by kshunz View Post
But if aircraft power is lost, the fuel pumps stop and the engine stops. So this backup battery is just to keep the EFIS running during the final glide? This makes me wonder whether there's something I don't understand.
If Gen A, Gen B dies, and you activate the EMS Battery Backup switch and restart the engine... Eventually your main battery will die. You'll have the EFIS battery to rely on for the rest of the way down.

You should realize too, that there are other ways in which the EFIS battery may be useful. Suppose there is a short on the circuit which is powering "EFIS" (PFD, MFD, AHARS, Magetometer).. that would take out all the displays. In that case, the EFIS battery could be used to power the PFD/AHARS using a separate power line that wouldn't be shorted.

I also need to mention here that I brought a wiring bug up to the attention of Support that hopefully will be fixed through a SB soon (my proposed fix to them was a very simple 1 hour job, so nobody panic!). In this last case I mention, the EFIS battery actually fails to work at all.
__________________
Rob Carsey, Winfield Park, NJ
RV-12iS (N713) / Completed 12/2020 / 350hrs and counting
ASEL, Glider, AGI/IGI, LSRM-I, FCC GROL
APRS Track or ADSBExchange Track

Last edited by rcarsey : 01-19-2023 at 01:03 PM.
Reply With Quote
  #8  
Old 01-19-2023, 03:45 PM
BobbyLucas's Avatar
BobbyLucas BobbyLucas is offline
 
Join Date: Oct 2019
Location: Belleville, MI
Posts: 399
Default

Quote:
Originally Posted by sparkcrafter View Post
There is a backup battery. See the attached schematic.

-Jerald
That is only for the EFIS, not the engine.
__________________
Bobby Steinmetz
Van Buren TWP, MI
RV-12iS #121228
Reply With Quote
  #9  
Old 01-21-2023, 10:43 AM
jrtens's Avatar
jrtens jrtens is offline
 
Join Date: Apr 2018
Location: Seattle
Posts: 293
Default

Welcome to VAF Scott. I think you will find that the 12iS is a great little airplane. Where is your flying club?
__________________
Jon
2019 12iS SLSA
KAWO
Reply With Quote
  #10  
Old 01-22-2023, 01:00 PM
subpar_bucker subpar_bucker is offline
 
Join Date: Oct 2016
Location: Cranberry Twp, PA
Posts: 73
Default

I have a dumb question prompted by a question I was asked by a friend: the 912iS engine's electrical system is powered by 2 generators correct? It sounds like it is possible to install external alternators if desired based upon this video:

https://www.youtube.com/watch?v=vgtq289Wj_Q

I was also wondering if there's a diagram that shows where on the 912iS the generators are located. Google so far has failed me.

When I answered my friend's question they pushed back with, "no new engines are using generators any longer, yours has to have an alternator..."
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 08:13 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.