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Rotax 914 Electric fuel pumps

 
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wdaniell.longport(at)gmai
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PostPosted: Thu Apr 05, 2018 8:25 am    Post subject: Rotax 914 Electric fuel pumps Reply with quote

I have the Europa System with one of the pumps connected direct to the alternator and the other to the bus.

I get the logic of a direct connection to the alternator.
Why isn't the other pump connected direct to the battery so that if the alternator fails you can switch off the buss run one pump off the battery?
(My EFIS has a back up battery and I carry a hand held so I can operate with the buss off.)
thanks 
Will

William Daniell

LONGPORT
+57 310 295 0744


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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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m.j.gregory(at)talk21.com
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PostPosted: Thu Apr 05, 2018 4:33 pm    Post subject: Rotax 914 Electric fuel pumps Reply with quote

Hello Will,

You could connect the second fuel pump direct to the battery, via a fuse/CB and switch as for the trim circuit, but why would you wish to?

In the event of alternator failure, unless you have a low-capacity main battery, you have plenty of time to shed loads according to how long you need to keep airborne. In the event of a forced landing and turning off the main bus with the master switch, the electric trim is kept operational to avoid heavy stick forces, but this logic does not apply to the fuel pump.

If the engine has stopped and you are making a forced landing, a single action to turn off the master switch before contact with the ground will kill all electrics (except the trim and your built-in standby batteries) and minimise the risk of a post-impact fire caused by an electrical short circuit and hefty current from the main battery.  In particular, it will also stop the fuel pumps from potentially squirting fuel all over the wreckage, without your having to remember to switch off your fuel pump off separately.

Of course, you would never shut down the engine after parking, turn off the master switch and forget to turn off your fuel pump!

Best wishes,

Mike
Dr Mike Gregory
Europa Club safety officer
01480 451655
07885 355765

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of William Daniell
Sent: 05 April 2018 17:25
To: europa-list(at)matronics.com
Subject: Rotax 914 Electric fuel pumps

I have the Europa System with one of the pumps connected direct to the alternator and the other to the bus.



I get the logic of a direct connection to the alternator.



Why isn't the other pump connected direct to the battery so that if the alternator fails you can switch off the buss run one pump off the battery?



(My EFIS has a back up battery and I carry a hand held so I can operate with the buss off.)



thanks



Will






William Daniell

LONGPORT
+57 310 295 0744


- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
wdaniell.longport(at)gmai
Guest





PostPosted: Fri Apr 06, 2018 6:11 am    Post subject: Rotax 914 Electric fuel pumps Reply with quote

Mike
Naturally I would never leave the pumps on after parking because I always use and follow my checklists Smile.  Actually mine are quite noisy Bosch injection pumps so its probably not likely.
Thanks for your comments, much appreciated and valid points.
My main aim is to simplify the electrical system precisely for safety sake.  I have a secondary aim which is my flight to the US.  There are some quite long legs over water or jungle (which amounts to the same thing).  I want to be able to maximize the electrical range by switching off all unnecessary electrical loads.  For me this includes everything except what is needed to run the engine range as my back up batteries and handheld devices will take care of the flying aspect.  
So ideally Id like to have one buss which I can switch off to achieve this minimal electrical load.    At the moment I think the only things which require separate switches are 
  • Master
  • mags
  • Avionics 1 - ADSB XPNDR RADIO Intercom
  • Avionics 2 - AP servos in case they start acting strangely I would like to able to switch them off separately.
  • Fuel Pumps x 2 - sometimes on the ground one wants to fiddle with the EFIS without the pump draining the battery.
  • Landing and Anti Col lights 

Connecting a pump to the battery might be a moot point because sudden and complete alternators failures are very rare and also my Rotax 912 turbo has a mechanical pump which in theory should maintain up to 29 in at sea level.  I have yet to test this.

Will


William Daniell

LONGPORT
+57 310 295 0744


On Thu, Apr 5, 2018 at 7:32 PM, Mike Gregory <m.j.gregory(at)talk21.com (m.j.gregory(at)talk21.com)> wrote:
Quote:

Hello Will,
 
You could connect the second fuel pump direct to the battery, via a fuse/CB and switch as for the trim circuit, but why would you wish to?
 
In the event of alternator failure, unless you have a low-capacity main battery, you have plenty of time to shed loads according to how long you need to keep airborne. In the event of a forced landing and turning off the main bus with the master switch, the electric trim is kept operational to avoid heavy stick forces, but this logic does not apply to the fuel pump.
 
If the engine has stopped and you are making a forced landing, a single action to turn off the master switch before contact with the ground will kill all electrics (except the trim and your built-in standby batteries) and minimise the risk of a post-impact fire caused by an electrical short circuit and hefty current from the main battery.  In particular, it will also stop the fuel pumps from potentially squirting fuel all over the wreckage, without your having to remember to switch off your fuel pump off separately.
 
Of course, you would never shut down the engine after parking, turn off the master switch and forget to turn off your fuel pump!
 
Best wishes,
 
Mike
Dr Mike Gregory
Europa Club safety officer
01480 451655
07885 355765
 
From: owner-europa-list-server(at)matronics.com (owner-europa-list-server(at)matronics.com) [mailto:owner-europa-list-server(at)matronics.com (owner-europa-list-server(at)matronics.com)] On Behalf Of William Daniell
Sent: 05 April 2018 17:25
To: europa-list(at)matronics.com (europa-list(at)matronics.com)
Subject: Rotax 914 Electric fuel pumps
 
I have the Europa System with one of the pumps connected direct to the alternator and the other to the bus.

 

I get the logic of a direct connection to the alternator.

 

Why isn't the other pump connected direct to the battery so that if the alternator fails you can switch off the buss run one pump off the battery?

 

(My EFIS has a back up battery and I carry a hand held so I can operate with the buss off.)

 

thanks 

 

Will

 

 
 

William Daniell

LONGPORT
+57 310 295 0744


- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
m.j.gregory(at)talk21.com
Guest





PostPosted: Fri Apr 06, 2018 9:47 am    Post subject: Rotax 914 Electric fuel pumps Reply with quote

Will,

You could achieve the objective of shedding all non-essential loads by turning off the master and having an “emergency bus” for essential items. This does not need to be elaborate – it could simply be a 3-way changeover switch for your second pump: BUS-OFF-BAT instead of the usual BUS-OFF.

In your case, with a mechanical pump that would normally keep the engine going unless you happen to be on full boost at the time of alternator failure, this would allow you to shed everything then switch the pump to BAT if you need it.

Good luck with your trip!

Best wishes,

Mike

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of William Daniell
Sent: 06 April 2018 15:11
To: europa-list(at)matronics.com
Subject: Re: Rotax 914 Electric fuel pumps

Mike



Naturally I would never leave the pumps on after parking because I always use and follow my checklists Smile. Actually mine are quite noisy Bosch injection pumps so its probably not likely.



Thanks for your comments, much appreciated and valid points.



My main aim is to simplify the electrical system precisely for safety sake. I have a secondary aim which is my flight to the US. There are some quite long legs over water or jungle (which amounts to the same thing). I want to be able to maximize the electrical range by switching off all unnecessary electrical loads. For me this includes everything except what is needed to run the engine range as my back up batteries and handheld devices will take care of the flying aspect.



So ideally Id like to have one buss which I can switch off to achieve this minimal electrical load. At the moment I think the only things which require separate switches are
  • Master
  • mags
  • Avionics 1 - ADSB XPNDR RADIO Intercom
  • Avionics 2 - AP servos in case they start acting strangely I would like to able to switch them off separately.
  • Fuel Pumps x 2 - sometimes on the ground one wants to fiddle with the EFIS without the pump draining the battery.
  • Landing and Anti Col lights


Connecting a pump to the battery might be a moot point because sudden and complete alternators failures are very rare and also my Rotax 912 turbo has a mechanical pump which in theory should maintain up to 29 in at sea level. I have yet to test this.



Will




William Daniell

LONGPORT
+57 310 295 0744



On Thu, Apr 5, 2018 at 7:32 PM, Mike Gregory <m.j.gregory(at)talk21.com (m.j.gregory(at)talk21.com)> wrote:
Hello Will,

You could connect the second fuel pump direct to the battery, via a fuse/CB and switch as for the trim circuit, but why would you wish to?

In the event of alternator failure, unless you have a low-capacity main battery, you have plenty of time to shed loads according to how long you need to keep airborne. In the event of a forced landing and turning off the main bus with the master switch, the electric trim is kept operational to avoid heavy stick forces, but this logic does not apply to the fuel pump.

If the engine has stopped and you are making a forced landing, a single action to turn off the master switch before contact with the ground will kill all electrics (except the trim and your built-in standby batteries) and minimise the risk of a post-impact fire caused by an electrical short circuit and hefty current from the main battery. In particular, it will also stop the fuel pumps from potentially squirting fuel all over the wreckage, without your having to remember to switch off your fuel pump off separately.

Of course, you would never shut down the engine after parking, turn off the master switch and forget to turn off your fuel pump!

Best wishes,

Mike
Dr Mike Gregory
Europa Club safety officer
01480 451655
07885 355765

From: owner-europa-list-server(at)matronics.com (owner-europa-list-server(at)matronics.com) [mailto:owner-europa-list-server(at)matronics.com (owner-europa-list-server(at)matronics.com)] On Behalf Of William Daniell
Sent: 05 April 2018 17:25
To: europa-list(at)matronics.com (europa-list(at)matronics.com)
Subject: Rotax 914 Electric fuel pumps

I have the Europa System with one of the pumps connected direct to the alternator and the other to the bus.



I get the logic of a direct connection to the alternator.



Why isn't the other pump connected direct to the battery so that if the alternator fails you can switch off the buss run one pump off the battery?



(My EFIS has a back up battery and I carry a hand held so I can operate with the buss off.)



thanks



Will






William Daniell

LONGPORT
+57 310 295 0744


- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
Back to top
wdaniell.longport(at)gmai
Guest





PostPosted: Fri Apr 06, 2018 11:31 am    Post subject: Rotax 914 Electric fuel pumps Reply with quote

Excellent, thanksWill

William Daniell
LONGPORT
+57 310 295 0744

On Fri, Apr 6, 2018, 12:50 Mike Gregory <m.j.gregory(at)talk21.com (m.j.gregory(at)talk21.com)> wrote:

Quote:

Will,
 
You could achieve the objective of shedding all non-essential loads by turning off the master and having an “emergency bus” for essential items. This does not need to be elaborate – it could simply be a 3-way changeover switch for your second pump: BUS-OFF-BAT instead of the usual BUS-OFF.
 
In your case, with a mechanical pump that would normally keep the engine going unless you happen to be on full boost at the time of alternator failure, this would allow you to shed everything then switch the pump to BAT if you need it.
 
Good luck with your trip!
 
Best wishes,
 
Mike
 
From: owner-europa-list-server(at)matronics.com (owner-europa-list-server(at)matronics.com) [mailto:owner-europa-list-server(at)matronics.com (owner-europa-list-server(at)matronics.com)] On Behalf Of William Daniell
Sent: 06 April 2018 15:11
To: europa-list(at)matronics.com (europa-list(at)matronics.com)
Subject: Re: Rotax 914 Electric fuel pumps
 
Mike

 

Naturally I would never leave the pumps on after parking because I always use and follow my checklists Smile.  Actually mine are quite noisy Bosch injection pumps so its probably not likely.

 

Thanks for your comments, much appreciated and valid points.

 

My main aim is to simplify the electrical system precisely for safety sake.  I have a secondary aim which is my flight to the US.  There are some quite long legs over water or jungle (which amounts to the same thing).  I want to be able to maximize the electrical range by switching off all unnecessary electrical loads.  For me this includes everything except what is needed to run the engine range as my back up batteries and handheld devices will take care of the flying aspect.  

 

So ideally Id like to have one buss which I can switch off to achieve this minimal electrical load.    At the moment I think the only things which require separate switches are 
  • Master
  • mags
  • Avionics 1 - ADSB XPNDR RADIO Intercom
  • Avionics 2 - AP servos in case they start acting strangely I would like to able to switch them off separately.
  • Fuel Pumps x 2 - sometimes on the ground one wants to fiddle with the EFIS without the pump draining the battery.
  • Landing and Anti Col lights 


Connecting a pump to the battery might be a moot point because sudden and complete alternators failures are very rare and also my Rotax 912 turbo has a mechanical pump which in theory should maintain up to 29 in at sea level.  I have yet to test this.

 

Will

 

 


William Daniell

LONGPORT
+57 310 295 0744


 
On Thu, Apr 5, 2018 at 7:32 PM, Mike Gregory <m.j.gregory(at)talk21.com (m.j.gregory(at)talk21.com)> wrote:
Hello Will,
 
You could connect the second fuel pump direct to the battery, via a fuse/CB and switch as for the trim circuit, but why would you wish to?
 
In the event of alternator failure, unless you have a low-capacity main battery, you have plenty of time to shed loads according to how long you need to keep airborne. In the event of a forced landing and turning off the main bus with the master switch, the electric trim is kept operational to avoid heavy stick forces, but this logic does not apply to the fuel pump.
 
If the engine has stopped and you are making a forced landing, a single action to turn off the master switch before contact with the ground will kill all electrics (except the trim and your built-in standby batteries) and minimise the risk of a post-impact fire caused by an electrical short circuit and hefty current from the main battery.  In particular, it will also stop the fuel pumps from potentially squirting fuel all over the wreckage, without your having to remember to switch off your fuel pump off separately.
 
Of course, you would never shut down the engine after parking, turn off the master switch and forget to turn off your fuel pump!
 
Best wishes,
 
Mike
Dr Mike Gregory
Europa Club safety officer
01480 451655
07885 355765
 
From: owner-europa-list-server(at)matronics.com (owner-europa-list-server(at)matronics.com) [mailto:owner-europa-list-server(at)matronics.com (owner-europa-list-server(at)matronics.com)] On Behalf Of William Daniell
Sent: 05 April 2018 17:25
To: europa-list(at)matronics.com (europa-list(at)matronics.com)
Subject: Rotax 914 Electric fuel pumps
 
I have the Europa System with one of the pumps connected direct to the alternator and the other to the bus.

 

I get the logic of a direct connection to the alternator.

 

Why isn't the other pump connected direct to the battery so that if the alternator fails you can switch off the buss run one pump off the battery?

 

(My EFIS has a back up battery and I carry a hand held so I can operate with the buss off.)

 

thanks 

 

Will

 

 
 

William Daniell

LONGPORT
+57 310 295 0744
 



- The Matronics Europa-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Europa-List
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