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  #11  
Old 10-14-2022, 02:41 PM
rv12is's Avatar
rv12is rv12is is offline
 
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Location: Peachtree City, GA
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Default

Quote:
Originally Posted by rcarsey View Post
I'd need to see the new schematics for the new HIC module. I'll map it out if they aren't published before I receive the new module..
It looks like the new schematic is now available. There is an RGB LED on the board for diagnostic purposes. The schematic describes it's operation as:
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  #12  
Old 10-14-2022, 09:48 PM
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philcam philcam is offline
 
Join Date: Aug 2005
Location: DFW, Texas
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Default POH

I'd like to see the revised POH. Page 4-2 of the current POH has the following warning: "During high ambient temperature conditions, run the fuel pump for 5 mins to flush the fuel lines and minimize the potential for vapor lock."

With the new HIC, this may not be possible. It appears the fuel pump will "time out" if left on for more than approximately 20 seconds without starting the engine.
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  #13  
Old 10-14-2022, 10:27 PM
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rcarsey rcarsey is offline
 
Join Date: Jul 2012
Location: North Brunswick, NJ
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Quote:
Originally Posted by rv12is View Post
It looks like the new schematic is now available. There is an RGB LED on the board for diagnostic purposes. The schematic describes it's operation as:
Attachment 32228
Looks like the changes are:
  1. IC01 has the source and drains reversed.
  2. IC02's drain is grounded
  3. Diagnostic LED addition.
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  #14  
Old 10-14-2022, 11:20 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,975
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Quote:
Originally Posted by philcam View Post
I'd like to see the revised POH. Page 4-2 of the current POH has the following warning: "During high ambient temperature conditions, run the fuel pump for 5 mins to flush the fuel lines and minimize the potential for vapor lock."

With the new HIC, this may not be possible. It appears the fuel pump will "time out" if left on for more than approximately 20 seconds without starting the engine.
If I remember correctly, the timer that controls the automatic activation of start power doesn’t start until the starter motor circuit is activated by the key.
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  #15  
Old 10-15-2022, 11:28 PM
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Tony Kirk Tony Kirk is offline
 
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Location: KDUH
Posts: 125
Default Start Button Bypass

The Start Button Bypass (SBB) is actually activated as soon as the Master Switch is turned on. As long as the main aircraft battery bus voltage is below the programmed threshold (~13.7V) the SBB circuit will stay activated indefinitely.

The problem we are seeing with the new AV-60009-2 HIC Module is people are testing the system with a battery charger connected (or just removed) and the bus voltage is above the threshold due to battery float charge. As soon as the SBB computer senses the bus voltage is above the threshold a 60 second timer is started, so 1 minute later the SBB circuit is shut off.

The EarthX battery has a very low self-discharge rate and should not need to be connected to a battery charger except during system testing when the Master Switch is on for extended periods of time and the aircraft isn't going to be flown soon, allowing the aircraft generator to charge the battery. I.E. While testing and configuring your systems before airworthiness.

There is no need to connect a battery charger between flights, in fact, the high float voltage will most likely cause your SBB circuit shut off sooner than you want it to. The EarthX documentation says the "resting voltage" of the battery as 13.3V, which works fine with this system unless the battery has just been charged.

You can reactivate the SBB circuit by flipping the Master Switch off and back on or engaging the starter with the key switch. Until the bus voltage is below the threshold the SBB will keep turning off in 1 minute.

This feature is detailed in the Flight Training Supplement, and the circuit is illustrated in the Pilot Operating Handbook.

RV-12iS FTS link.

POH link.

As stated in the FTS, the SBB circuit will be re-activated any time the key switch is turned to the start position, as in an engine restart scenario.

Other aircraft that use the 912iS engine have a manually activated switch for the "Start Button" which is not as convenient to use while turning a key for the starter and working the throttle AND holding the Start Switch. Particularly, if you are also flying the airplane!

Please read all your manuals, including the Rotax published manuals, so you have a thorough understand of how your aircraft systems work.
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RV-7 N777RV, AirVenture 2022 Kitbuilt Bronze Lindy Winner!
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  #16  
Old 10-16-2022, 06:36 PM
AviatorMav AviatorMav is offline
 
Join Date: Sep 2020
Location: Calera, Oklahoma
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Tony,

Looks like that links to the POH revision posted in Feb (Rev 8). The new SB explicitly directs the reader to "Please review and operate using the new emergency procedures listed in the RV-12iS POH after completing this service bulletin. Ensure the correct, up-to-date version of the POH is carried in the aircraft." It would be nice to understand the behavior of the new HIC module in an emergency. Based on the verbiage of the SB, this is a safety-critical POH update and certainly should have been provided with the SB.

Can't say that I'm too thrilled with the idea of needing to ensure the SBB circuit is reactivated to restart the pumps. Just one more thing to further complicate an emergency situation. The current shutdown procedure has you turning off the pumps immediately following shutdown. Is there actually a benefit to them shutting off automatically a few seconds earlier?

Quote:
Originally Posted by Tony Kirk View Post
The Start Button Bypass (SBB) is actually activated as soon as the Master Switch is turned on. As long as the main aircraft battery bus voltage is below the programmed threshold (~13.7V) the SBB circuit will stay activated indefinitely.

The problem we are seeing with the new AV-60009-2 HIC Module is people are testing the system with a battery charger connected (or just removed) and the bus voltage is above the threshold due to battery float charge. As soon as the SBB computer senses the bus voltage is above the threshold a 60 second timer is started, so 1 minute later the SBB circuit is shut off.

The EarthX battery has a very low self-discharge rate and should not need to be connected to a battery charger except during system testing when the Master Switch is on for extended periods of time and the aircraft isn't going to be flown soon, allowing the aircraft generator to charge the battery. I.E. While testing and configuring your systems before airworthiness.

There is no need to connect a battery charger between flights, in fact, the high float voltage will most likely cause your SBB circuit shut off sooner than you want it to. The EarthX documentation says the "resting voltage" of the battery as 13.3V, which works fine with this system unless the battery has just been charged.

You can reactivate the SBB circuit by flipping the Master Switch off and back on or engaging the starter with the key switch. Until the bus voltage is below the threshold the SBB will keep turning off in 1 minute.

This feature is detailed in the Flight Training Supplement, and the circuit is illustrated in the Pilot Operating Handbook.

RV-12iS FTS link.

POH link.

As stated in the FTS, the SBB circuit will be re-activated any time the key switch is turned to the start position, as in an engine restart scenario.

Other aircraft that use the 912iS engine have a manually activated switch for the "Start Button" which is not as convenient to use while turning a key for the starter and working the throttle AND holding the Start Switch. Particularly, if you are also flying the airplane!

Please read all your manuals, including the Rotax published manuals, so you have a thorough understand of how your aircraft systems work.
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  #17  
Old 10-16-2022, 10:48 PM
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Tony Kirk Tony Kirk is offline
 
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I don't think a revised POH is coming or it would have been published when the SB was released. Nothing in the way the new HIC Module functions has changed the previously published information in the POH Emergency section.

POH Rev. 8, page 3-15, 3.5.3.1 procedures still apply.
3.5.3.1 ENGINE AIR RESTART ROTAX 912 iS
• Maintain Airspeed – 60 KIAS minimum (see note below)
• Smart Glide – Hold Direct-To Button on G3X (Garmin Only)
• Lane A & B Switches – BOTH ON
• EMS Backup Battery Switch – ON
• Fuel Pump Switches – BOTH ON
• Fuel Shut-Off Valve – CHECK ON – DOWN
• Throttle – SET TO 55% - 65% OPEN
• Spar Pin Override Switch – HOLD DOWN
• Ignition Key – ENGAGE
• If restart not possible, change throttle settings in attempt to
restart
• Follow 3.6.2 “Forced Landing” procedures if unable to restart
If you study the POH schematic I posted previously, you will see the EMS Backup Battery Switch (BBS) connects the Main (Aircraft) Bus directly to the 912iS EMS Bus A. The BBS serves the exact same purpose as the SBB circuit in the HIC Module does - to supply battery bus power directly to the EMS system - only more directly.

To address your second point. I guess I wasn't clear in pointing out that in normal operating circumstances you should not be connecting a battery charger to your aircraft. The EarthX battery will be fine for a month (or two) without charging. There should be no parasitic loads that will drain the battery between flights.

And if you follow this advice, the first sentence of my previous post is how the SBB circuit will function.

As long as the main aircraft battery bus voltage is below the programmed threshold (~13.7V) the SBB circuit will stay activated indefinitely.

To answer your question as to why the system shuts off your fuel pumps automatically.

During normal operations Rotax designed the EMS system, including the fuel pumps, to be powered by the Generator A. NOT the SBB or the EMS BBS!

The SBB and the EMS BBS connect the main bus to the EMS A bus for starting and if both generators fail in flight. Period.

If you suffer an engine failure, prop strike or a crash - anything that stops generator A from powering the EMS - the fuel pumps will shut off. That would probably be a good thing if you severed a fuel line in the crash!

Rotax designed the system and Van's implemented Rotax's design in the RV-12iS electrical system. I invite you to review the Rotax Installation Manual, where you will find the attached Rotax schematic.


Quote:
Originally Posted by AviatorMav View Post
Tony,

Looks like that links to the POH revision posted in Feb (Rev 8). The new SB explicitly directs the reader to "Please review and operate using the new emergency procedures listed in the RV-12iS POH after completing this service bulletin. Ensure the correct, up-to-date version of the POH is carried in the aircraft." It would be nice to understand the behavior of the new HIC module in an emergency. Based on the verbiage of the SB, this is a safety-critical POH update and certainly should have been provided with the SB.

Can't say that I'm too thrilled with the idea of needing to ensure the SBB circuit is reactivated to restart the pumps. Just one more thing to further complicate an emergency situation. The current shutdown procedure has you turning off the pumps immediately following shutdown. Is there actually a benefit to them shutting off automatically a few seconds earlier?
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RV-7 N777RV, AirVenture 2022 Kitbuilt Bronze Lindy Winner!
My story in Kitplanes August 2022 - Stick To the Plans
RV-6A N57TK, first flight 9/5/05...
Sold in 2011 after 725 hours of pure joy!

Last edited by Tony Kirk : 10-17-2022 at 07:49 AM. Reason: Tyop ;)
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  #18  
Old 10-17-2022, 06:44 AM
Bob Y Bob Y is offline
 
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Tony, the FTS also states that “Using both fuel pumps during engine start could cause damage to the engine...” I have been led to believe starting on one pump simply keeps a low charged battery from being pulled too low with both pumps running, yet the air start procedure states to have both running. Not sure what “engine damage” could occur from this. Can you elaborate on this apparent discrepancy? Thanks.
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  #19  
Old 10-17-2022, 07:45 AM
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Tony Kirk Tony Kirk is offline
 
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The Starting instructions come from the Rotax Operators Manual (something else all 912iS operators should read!) which states:

ATTENTION
Only switch on one fuel pump when starting the engine. Switching
on both fuel pumps can lead to a bad start behavior.
I don't know why "engine damage" was the term chosen to for the statement in the FTS. It's possible "bad start behavior" could lead to starter damage or excessive wear?

During an Air Restart procedure you want to be sure that everything that makes the engine run is activated. And the procedure should be simple enough that it can be committed to memory for instant recall. This is also why the EMS Backup Battery Switch was placed next to the fuel pump switches!

Remember, both fuel pumps should be running at all times after the engine is started, as per the FTS. Also, the EMS Backup Battery Switch (BBS) should always be off unless both generators have failed. See attachment and read the POH & FTS, what you learn could save your life.
.
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Opinions, information and comments are my own unless stated otherwise.
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Tony Kirk
Van's Aircraft Tech Support (working from home)
RV-7 N777RV, AirVenture 2022 Kitbuilt Bronze Lindy Winner!
My story in Kitplanes August 2022 - Stick To the Plans
RV-6A N57TK, first flight 9/5/05...
Sold in 2011 after 725 hours of pure joy!

Last edited by Tony Kirk : 10-19-2022 at 01:47 PM. Reason: Upload OM page & FTS Fuel Pump instructions.
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  #20  
Old 10-19-2022, 05:15 PM
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greghughespdx greghughespdx is offline
 
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Default SB-00058 updated to Rev 1

We've published REV 1 of SB-00058 (the original website link remains the same), in which we removed the erroneous reference to an updated POH procedure. Please refer to the new revision of the doc. Thanks, and sorry for the inconvenience associated with the info error on the original version.
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