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kenryan
Joined: 20 Oct 2009
Posts: 429
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 Posted: Thu Oct 06, 2016 1:01 pm Post subject: rotax generator without battery |
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Per this document:
The fuel regulator is mounted on the airbox and plays a critical role in maintaining fuel pressure to a minimum 0.15 BAR (2.18 PSI or 4.45”) above airbox boost pressure. The regulator is calibrated at the factory and normally no adjustments are required. In the event that the fuel pressure gets too low, due to a maladjustment or malfunction of the fuel regulator, the engine would experience fuel starvation due to the higher airbox pressure sensed in the carburetor float bowls not allowing the fuel supply to enter. A high fuel pressure can result from regulator maladjustment, malfunction or restriction in return line.
A properly adjusted fuel regulator will maintain fuel pressure above airbox pressure within the following parameters:
Maximum fuel pressure is 0.35 BAR (5.08 PSI or 10.36”) above airbox pressure
Minimum fuel pressure is 0.15 BAR (2.18 PSI or 4.45”) above airbox pressure
Normal fuel pressure is 0.25 BAR (3.63 PSI or 7.41”) above airbox pressure
On Thu, Oct 6, 2016 at 12:42 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 10:39 AM 10/6/2016, you wrote:
| Quote: | | Bob, the 914 engine is not fuel injected, but it is turbocharged and there is a fuel pressure regulator that maintains a constant fuel pressure over air pressure produced by the turbo. |
Do you know what the pressure setting is?
Bob . . .
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kenryan
Joined: 20 Oct 2009
Posts: 429
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| Posted: Thu Oct 06, 2016 4:13 pm Post subject: rotax generator without battery |
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I found this Pressure Switch which seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning.
On Thu, Oct 6, 2016 at 12:58 PM, GTH <gilles.thesee(at)free.fr (gilles.thesee(at)free.fr)> wrote:
| Quote: | Le 06/10/2016 à 22:42, Robert L. Nuckolls, III a écrit :
| Quote: | At 10:39 AM 10/6/2016, you wrote:
| Quote: | | Bob, the 914 engine is not fuel injected, but it is turbocharged and there is a fuel pressure regulator that maintains a constant fuel pressure over air pressure produced by the turbo. |
Do you know what the pressure setting is?
|
Airbox pressure + 0.25 bar (+- 0.10 bar)
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
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gilles.thesee(at)free.fr
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ashleysc(at)broadstripe.n
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| Posted: Fri Oct 07, 2016 6:07 am Post subject: rotax generator without battery |
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Hi Ken;
Advice from an old electro-mechanical engineer (now 76) and new pilot ((at) 70): Keep the pilot in charge of turning things off.
Cheers! Stu.
From: "GTH" <gilles.thesee(at)free.fr>
To: aeroelectric-list(at)matronics.com
Sent: Friday, October 7, 2016 12:17:19 AM
Subject: Re: rotax generator without battery
Le 07/10/2016 à 02:09, Ken Ryan a écrit :
| Quote: | I found this Pressure Switch which seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning.
|
Your call. You'll make your engine operation dependent on a switch and a relay.
"On a switch and a prayer" 
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
| | - The Matronics AeroElectric-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:
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JOHN TIPTON
Joined: 17 Sep 2006
Posts: 239
Location: Torquay - England
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| Posted: Fri Oct 07, 2016 7:33 am Post subject: rotax generator without battery |
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Q: how does the engine get it's fuel for start-up, the engine being off ie: no oil pressure
Sent from my iPad
----x--O--x----
On 7 Oct 2016, at 02:51 pm, ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net) wrote:
| Quote: | Hi Ken;
Advice from an old electro-mechanical engineer (now 76) and new pilot ((at) 70): Keep the pilot in charge of turning things off.
Cheers! Stu.
From: "GTH" <gilles.thesee(at)free.fr (gilles.thesee(at)free.fr)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Friday, October 7, 2016 12:17:19 AM
Subject: Re: rotax generator without battery
Le 07/10/2016 à 02:09, Ken Ryan a écrit :
| Quote: | I found this Pressure Switch which seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning.
|
Your call. You'll make your engine operation dependent on a switch and a relay.
"On a switch and a prayer"
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
|
| | - The Matronics AeroElectric-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:
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kenryan
Joined: 20 Oct 2009
Posts: 429
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| Posted: Fri Oct 07, 2016 8:29 am Post subject: rotax generator without battery |
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I think maybe some of you are not factoring in that this is on the auxiliary fuel pump only. So for a failure of the switch or relay to have any effect on the flight, the main fuel pump would have already had to fail. The primary fuel pump stops automatically when the engine stops turning because it is powered off the generator.
As far as startup, I think the way the pressure switch works is that it is a single pole, double throw. So there are three terminals: Comm, L1, and L2. Without pressure, Comm is connected to L2. With pressure, Comm is connected to L1.
The Comm goes to the fuel pump relay.
L1 goes to a fuel pump switch.
L2 goes to the starter side of the starter relay.
So at startup, because the pressure switch without pressure is connected Comm-L2 only, closing the fuel pump switch would do nothing. But when cranking power is put to the starter, current would flow to the relay through the Comm-L2 connection. Then, when the engine starts and current is removed from the starter circuit, power continues to flow the fuel pump relay because now with 7lbs of oil pressure Comm is connected to L1 (and the switch has been turned on).
On Fri, Oct 7, 2016 at 7:30 AM, John Tipton <jmtipton(at)btopenworld.com (jmtipton(at)btopenworld.com)> wrote:
| Quote: | Q: how does the engine get it's fuel for start-up, the engine being off ie: no oil pressure
Sent from my iPad
----x--O--x----
On 7 Oct 2016, at 02:51 pm, ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net) wrote:
| Quote: | Hi Ken;
Advice from an old electro-mechanical engineer (now 76) and new pilot ((at) 70): Keep the pilot in charge of turning things off.
Cheers! Stu.
From: "GTH" <gilles.thesee(at)free.fr (gilles.thesee(at)free.fr)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Friday, October 7, 2016 12:17:19 AM
Subject: Re: AeroElectric-List: rotax generator without battery
Le 07/10/2016 à 02:09, Ken Ryan a écrit :
| Quote: | I found this Pressure Switch which seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning.
|
Your call. You'll make your engine operation dependent on a switch and a relay.
"On a switch and a prayer"
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
|
|
| | - The Matronics AeroElectric-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?AeroElectric-List |
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alec(at)alecmyers.com
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| Posted: Fri Oct 07, 2016 11:01 am Post subject: rotax generator without battery |
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In that case why do you need the backup pump energised at all, absent a main fuel pump failure?
Many (most?) TC aircraft with fuel injection or low-wing tanks have an electric backup pump but it's either on only for takeoff and landing and switching tanks (Piper, Grumman) or only used for priming and in the event of engine storage due to main pump failure (Cessna)
I'm not familiar with the proposed system so If the backup pump is permanently energised what alerts the pilot to a failure of the engine-driven pump?
On Oct 7, 2016, at 12:27 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | I think maybe some of you are not factoring in that this is on the auxiliary fuel pump only. So for a failure of the switch or relay to have any effect on the flight, the main fuel pump would have already had to fail. The primary fuel pump stops automatically when the engine stops turning because it is powered off the generator.
As far as startup, I think the way the pressure switch works is that it is a single pole, double throw. So there are three terminals: Comm, L1, and L2. Without pressure, Comm is connected to L2. With pressure, Comm is connected to L1.
The Comm goes to the fuel pump relay.
L1 goes to a fuel pump switch.
L2 goes to the starter side of the starter relay.
So at startup, because the pressure switch without pressure is connected Comm-L2 only, closing the fuel pump switch would do nothing. But when cranking power is put to the starter, current would flow to the relay through the Comm-L2 connection. Then, when the engine starts and current is removed from the starter circuit, power continues to flow the fuel pump relay because now with 7lbs of oil pressure Comm is connected to L1 (and the switch has been turned on).
On Fri, Oct 7, 2016 at 7:30 AM, John Tipton <jmtipton(at)btopenworld.com (jmtipton(at)btopenworld.com)> wrote:
| Quote: | Q: how does the engine get it's fuel for start-up, the engine being off ie: no oil pressure
Sent from my iPad
----x--O--x----
On 7 Oct 2016, at 02:51 pm, ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net) wrote:
| Quote: | Hi Ken;
Advice from an old electro-mechanical engineer (now 76) and new pilot ((at) 70): Keep the pilot in charge of turning things off.
Cheers! Stu.
From: "GTH" <gilles.thesee(at)free.fr (gilles.thesee(at)free.fr)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Friday, October 7, 2016 12:17:19 AM
Subject: Re: AeroElectric-List: rotax generator without battery
Le 07/10/2016 à 02:09, Ken Ryan a écrit :
| Quote: | I found this Pressure Switchwhich seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning.
|
Your call. You'll make your engine operation dependent on a switch and a relay.
"On a switch and a prayer"
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
|
|
|
| | - The Matronics AeroElectric-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?AeroElectric-List |
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kenryan
Joined: 20 Oct 2009
Posts: 429
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| Posted: Fri Oct 07, 2016 11:21 am Post subject: rotax generator without battery |
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Rotax operating procedures for 914 call for running both electric fuel pumps for takeoff and landings.
On Fri, Oct 7, 2016 at 10:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
In that case why do you need the backup pump energised at all, absent a main fuel pump failure?
Many (most?) TC aircraft with fuel injection or low-wing tanks have an electric backup pump but it's either on only for takeoff and landing and switching tanks (Piper, Grumman) or only used for priming and in the event of engine storage due to main pump failure (Cessna)
I'm not familiar with the proposed system so If the backup pump is permanently energised what alerts the pilot to a failure of the engine-driven pump?
On Oct 7, 2016, at 12:27 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | I think maybe some of you are not factoring in that this is on the auxiliary fuel pump only. So for a failure of the switch or relay to have any effect on the flight, the main fuel pump would have already had to fail. The primary fuel pump stops automatically when the engine stops turning because it is powered off the generator.
As far as startup, I think the way the pressure switch works is that it is a single pole, double throw. So there are three terminals: Comm, L1, and L2. Without pressure, Comm is connected to L2. With pressure, Comm is connected to L1.
The Comm goes to the fuel pump relay.
L1 goes to a fuel pump switch.
L2 goes to the starter side of the starter relay.
So at startup, because the pressure switch without pressure is connected Comm-L2 only, closing the fuel pump switch would do nothing. But when cranking power is put to the starter, current would flow to the relay through the Comm-L2 connection. Then, when the engine starts and current is removed from the starter circuit, power continues to flow the fuel pump relay because now with 7lbs of oil pressure Comm is connected to L1 (and the switch has been turned on).
On Fri, Oct 7, 2016 at 7:30 AM, John Tipton <jmtipton(at)btopenworld.com (jmtipton(at)btopenworld.com)> wrote:
| Quote: | Q: how does the engine get it's fuel for start-up, the engine being off ie: no oil pressure
Sent from my iPad
----x--O--x----
On 7 Oct 2016, at 02:51 pm, ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net) wrote:
| Quote: | Hi Ken;
Advice from an old electro-mechanical engineer (now 76) and new pilot ((at) 70): Keep the pilot in charge of turning things off.
Cheers! Stu.
From: "GTH" <gilles.thesee(at)free.fr (gilles.thesee(at)free.fr)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Friday, October 7, 2016 12:17:19 AM
Subject: Re: AeroElectric-List: rotax generator without battery
Le 07/10/2016 à 02:09, Ken Ryan a écrit :
| Quote: | I found this Pressure Switch which seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning.
|
Your call. You'll make your engine operation dependent on a switch and a relay.
"On a switch and a prayer"
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
|
|
|
|
| | - The Matronics AeroElectric-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?AeroElectric-List |
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| Back to top |
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alec(at)alecmyers.com
Guest
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| Posted: Fri Oct 07, 2016 12:01 pm Post subject: rotax generator without battery |
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That's very reasonable; why not just have an on-off switch for the backup pump? Switch it on on the ground to test, on for takeoff and landing and off the rest of the time.
Is there a benefit to having it run full time in parallel with the main pump? how do you tell if the main pump has failed if the backup is already running?
On Oct 7, 2016, at 15:19, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Rotax operating procedures for 914 call for running both electric fuel pumps for takeoff and landings.
On Fri, Oct 7, 2016 at 10:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
In that case why do you need the backup pump energised at all, absent a main fuel pump failure?
Many (most?) TC aircraft with fuel injection or low-wing tanks have an electric backup pump but it's either on only for takeoff and landing and switching tanks (Piper, Grumman) or only used for priming and in the event of engine storage due to main pump failure (Cessna)
I'm not familiar with the proposed system so If the backup pump is permanently energised what alerts the pilot to a failure of the engine-driven pump?
On Oct 7, 2016, at 12:27 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | I think maybe some of you are not factoring in that this is on the auxiliary fuel pump only. So for a failure of the switch or relay to have any effect on the flight, the main fuel pump would have already had to fail. The primary fuel pump stops automatically when the engine stops turning because it is powered off the generator.
As far as startup, I think the way the pressure switch works is that it is a single pole, double throw. So there are three terminals: Comm, L1, and L2. Without pressure, Comm is connected to L2. With pressure, Comm is connected to L1.
The Comm goes to the fuel pump relay.
L1 goes to a fuel pump switch.
L2 goes to the starter side of the starter relay.
So at startup, because the pressure switch without pressure is connected Comm-L2 only, closing the fuel pump switch would do nothing. But when cranking power is put to the starter, current would flow to the relay through the Comm-L2 connection. Then, when the engine starts and current is removed from the starter circuit, power continues to flow the fuel pump relay because now with 7lbs of oil pressure Comm is connected to L1 (and the switch has been turned on).
On Fri, Oct 7, 2016 at 7:30 AM, John Tipton <jmtipton(at)btopenworld.com (jmtipton(at)btopenworld.com)> wrote:
| Quote: | Q: how does the engine get it's fuel for start-up, the engine being off ie: no oil pressure
Sent from my iPad
----x--O--x----
On 7 Oct 2016, at 02:51 pm, ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net) wrote:
| Quote: | Hi Ken;
Advice from an old electro-mechanical engineer (now 76) and new pilot ((at) 70): Keep the pilot in charge of turning things off.
Cheers! Stu.
From: "GTH" <gilles.thesee(at)free.fr (gilles.thesee(at)free.fr)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Friday, October 7, 2016 12:17:19 AM
Subject: Re: rotax generator without battery
Le 07/10/2016 à 02:09, Ken Ryan a écrit :
| Quote: | I found this Pressure Switch which seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning.
|
Your call. You'll make your engine operation dependent on a switch and a relay.
"On a switch and a prayer"
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
|
|
|
|
| | - The Matronics AeroElectric-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?AeroElectric-List |
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kenryan
Joined: 20 Oct 2009
Posts: 429
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| Posted: Fri Oct 07, 2016 12:17 pm Post subject: rotax generator without battery |
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Alec,
I'm not sure where you got the idea that the auxiliary pump would be running all the time. It would indeed be used only for takeoffs and landings, via a toggle switch. But inserting the pressure switch and the relay would insure that in the event of a crash, such as on takeoff or landing, the auxiliary pump would automatically shut down when the engine ceases to turn (because the oil pressure would drop).
Ken
On Fri, Oct 7, 2016 at 11:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
That's very reasonable; why not just have an on-off switch for the backup pump? Switch it on on the ground to test, on for takeoff and landing and off the rest of the time.
Is there a benefit to having it run full time in parallel with the main pump? how do you tell if the main pump has failed if the backup is already running?
On Oct 7, 2016, at 15:19, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Rotax operating procedures for 914 call for running both electric fuel pumps for takeoff and landings.
On Fri, Oct 7, 2016 at 10:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
In that case why do you need the backup pump energised at all, absent a main fuel pump failure?
Many (most?) TC aircraft with fuel injection or low-wing tanks have an electric backup pump but it's either on only for takeoff and landing and switching tanks (Piper, Grumman) or only used for priming and in the event of engine storage due to main pump failure (Cessna)
I'm not familiar with the proposed system so If the backup pump is permanently energised what alerts the pilot to a failure of the engine-driven pump?
On Oct 7, 2016, at 12:27 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | I think maybe some of you are not factoring in that this is on the auxiliary fuel pump only. So for a failure of the switch or relay to have any effect on the flight, the main fuel pump would have already had to fail. The primary fuel pump stops automatically when the engine stops turning because it is powered off the generator.
As far as startup, I think the way the pressure switch works is that it is a single pole, double throw. So there are three terminals: Comm, L1, and L2. Without pressure, Comm is connected to L2. With pressure, Comm is connected to L1.
The Comm goes to the fuel pump relay.
L1 goes to a fuel pump switch.
L2 goes to the starter side of the starter relay.
So at startup, because the pressure switch without pressure is connected Comm-L2 only, closing the fuel pump switch would do nothing. But when cranking power is put to the starter, current would flow to the relay through the Comm-L2 connection. Then, when the engine starts and current is removed from the starter circuit, power continues to flow the fuel pump relay because now with 7lbs of oil pressure Comm is connected to L1 (and the switch has been turned on).
On Fri, Oct 7, 2016 at 7:30 AM, John Tipton <jmtipton(at)btopenworld.com (jmtipton(at)btopenworld.com)> wrote:
| Quote: | Q: how does the engine get it's fuel for start-up, the engine being off ie: no oil pressure
Sent from my iPad
----x--O--x----
On 7 Oct 2016, at 02:51 pm, ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net) wrote:
| Quote: | Hi Ken;
Advice from an old electro-mechanical engineer (now 76) and new pilot ((at) 70): Keep the pilot in charge of turning things off.
Cheers! Stu.
From: "GTH" <gilles.thesee(at)free.fr (gilles.thesee(at)free.fr)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Friday, October 7, 2016 12:17:19 AM
Subject: Re: rotax generator without battery
Le 07/10/2016 à 02:09, Ken Ryan a écrit :
| Quote: | I found this Pressure Switch which seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning.
|
Your call. You'll make your engine operation dependent on a switch and a relay.
"On a switch and a prayer"
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
|
|
|
|
|
| | - The Matronics AeroElectric-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?AeroElectric-List |
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ceengland7(at)gmail.com
Guest
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| Posted: Fri Oct 07, 2016 1:43 pm Post subject: rotax generator without battery |
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It really comes down to probability, modified by your personal risk tolerance. What are the odds of actually needing the auto-off function of the aux pump (remember that in t/o-landing modes the other pump will be running, too; what auto-protects that one?), vs the likelihood of needing the backup pump (primary failure) and risking any one of the various wires, connectors, pressure switch, pressure *line*, etc causing loss of the pump? Or actually *causing* a problem (pressure line or pressure switch opening an oil exit path comes to mind...).
In the 'simple' scenario, the aux pump switch mounted next to the primary pump switch allows one swipe to get both, if a crash is imminent.
But if the auto feature makes you more comfortable, go for it.
Charlie
On Fri, Oct 7, 2016 at 3:14 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | Alec,
I'm not sure where you got the idea that the auxiliary pump would be running all the time. It would indeed be used only for takeoffs and landings, via a toggle switch. But inserting the pressure switch and the relay would insure that in the event of a crash, such as on takeoff or landing, the auxiliary pump would automatically shut down when the engine ceases to turn (because the oil pressure would drop).
Ken
On Fri, Oct 7, 2016 at 11:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
That's very reasonable; why not just have an on-off switch for the backup pump? Switch it on on the ground to test, on for takeoff and landing and off the rest of the time.
Is there a benefit to having it run full time in parallel with the main pump? how do you tell if the main pump has failed if the backup is already running?
On Oct 7, 2016, at 15:19, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Rotax operating procedures for 914 call for running both electric fuel pumps for takeoff and landings.
On Fri, Oct 7, 2016 at 10:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
In that case why do you need the backup pump energised at all, absent a main fuel pump failure?
Many (most?) TC aircraft with fuel injection or low-wing tanks have an electric backup pump but it's either on only for takeoff and landing and switching tanks (Piper, Grumman) or only used for priming and in the event of engine storage due to main pump failure (Cessna)
I'm not familiar with the proposed system so If the backup pump is permanently energised what alerts the pilot to a failure of the engine-driven pump?
On Oct 7, 2016, at 12:27 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | I think maybe some of you are not factoring in that this is on the auxiliary fuel pump only. So for a failure of the switch or relay to have any effect on the flight, the main fuel pump would have already had to fail. The primary fuel pump stops automatically when the engine stops turning because it is powered off the generator.
As far as startup, I think the way the pressure switch works is that it is a single pole, double throw. So there are three terminals: Comm, L1, and L2. Without pressure, Comm is connected to L2. With pressure, Comm is connected to L1.
The Comm goes to the fuel pump relay.
L1 goes to a fuel pump switch.
L2 goes to the starter side of the starter relay.
So at startup, because the pressure switch without pressure is connected Comm-L2 only, closing the fuel pump switch would do nothing. But when cranking power is put to the starter, current would flow to the relay through the Comm-L2 connection. Then, when the engine starts and current is removed from the starter circuit, power continues to flow the fuel pump relay because now with 7lbs of oil pressure Comm is connected to L1 (and the switch has been turned on).
On Fri, Oct 7, 2016 at 7:30 AM, John Tipton <jmtipton(at)btopenworld.com (jmtipton(at)btopenworld.com)> wrote:
| Quote: | Q: how does the engine get it's fuel for start-up, the engine being off ie: no oil pressure
Sent from my iPad
----x--O--x----
On 7 Oct 2016, at 02:51 pm, ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net) wrote:
| Quote: | Hi Ken;
Advice from an old electro-mechanical engineer (now 76) and new pilot ((at) 70): Keep the pilot in charge of turning things off.
Cheers! Stu.
From: "GTH" <gilles.thesee(at)free.fr (gilles.thesee(at)free.fr)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Friday, October 7, 2016 12:17:19 AM
Subject: Re: rotax generator without battery
Le 07/10/2016 à 02:09, Ken Ryan a écrit :
| Quote: | I found this Pressure Switch which seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning.
|
Your call. You'll make your engine operation dependent on a switch and a relay.
"On a switch and a prayer"
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
|
|
|
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kenryan
Joined: 20 Oct 2009
Posts: 429
|
| Posted: Fri Oct 07, 2016 2:01 pm Post subject: rotax generator without battery |
|
|
Charlie,
The primary pump is powered by the integrated generator, so it already has auto shut off.
What are the odds? Well, in off airport operations here in Alaska the odds are probably higher than high altitude ops over midwest farm fields from one 6,000 foot paved runways to the next. I know more than one guy who has flipped his airplane, and they all say the same thing: it happened in an instant with no warning. Fortunately, they all walked away.
Ken
On Fri, Oct 7, 2016 at 1:41 PM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:
| Quote: | It really comes down to probability, modified by your personal risk tolerance. What are the odds of actually needing the auto-off function of the aux pump (remember that in t/o-landing modes the other pump will be running, too; what auto-protects that one?), vs the likelihood of needing the backup pump (primary failure) and risking any one of the various wires, connectors, pressure switch, pressure *line*, etc causing loss of the pump? Or actually *causing* a problem (pressure line or pressure switch opening an oil exit path comes to mind...).
In the 'simple' scenario, the aux pump switch mounted next to the primary pump switch allows one swipe to get both, if a crash is imminent.
But if the auto feature makes you more comfortable, go for it.
Charlie
On Fri, Oct 7, 2016 at 3:14 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | Alec,
I'm not sure where you got the idea that the auxiliary pump would be running all the time. It would indeed be used only for takeoffs and landings, via a toggle switch. But inserting the pressure switch and the relay would insure that in the event of a crash, such as on takeoff or landing, the auxiliary pump would automatically shut down when the engine ceases to turn (because the oil pressure would drop).
Ken
On Fri, Oct 7, 2016 at 11:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
That's very reasonable; why not just have an on-off switch for the backup pump? Switch it on on the ground to test, on for takeoff and landing and off the rest of the time.
Is there a benefit to having it run full time in parallel with the main pump? how do you tell if the main pump has failed if the backup is already running?
On Oct 7, 2016, at 15:19, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Rotax operating procedures for 914 call for running both electric fuel pumps for takeoff and landings.
On Fri, Oct 7, 2016 at 10:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
In that case why do you need the backup pump energised at all, absent a main fuel pump failure?
Many (most?) TC aircraft with fuel injection or low-wing tanks have an electric backup pump but it's either on only for takeoff and landing and switching tanks (Piper, Grumman) or only used for priming and in the event of engine storage due to main pump failure (Cessna)
I'm not familiar with the proposed system so If the backup pump is permanently energised what alerts the pilot to a failure of the engine-driven pump?
On Oct 7, 2016, at 12:27 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | I think maybe some of you are not factoring in that this is on the auxiliary fuel pump only. So for a failure of the switch or relay to have any effect on the flight, the main fuel pump would have already had to fail. The primary fuel pump stops automatically when the engine stops turning because it is powered off the generator.
As far as startup, I think the way the pressure switch works is that it is a single pole, double throw. So there are three terminals: Comm, L1, and L2. Without pressure, Comm is connected to L2. With pressure, Comm is connected to L1.
The Comm goes to the fuel pump relay.
L1 goes to a fuel pump switch.
L2 goes to the starter side of the starter relay.
So at startup, because the pressure switch without pressure is connected Comm-L2 only, closing the fuel pump switch would do nothing. But when cranking power is put to the starter, current would flow to the relay through the Comm-L2 connection. Then, when the engine starts and current is removed from the starter circuit, power continues to flow the fuel pump relay because now with 7lbs of oil pressure Comm is connected to L1 (and the switch has been turned on).
On Fri, Oct 7, 2016 at 7:30 AM, John Tipton <jmtipton(at)btopenworld.com (jmtipton(at)btopenworld.com)> wrote:
| Quote: | Q: how does the engine get it's fuel for start-up, the engine being off ie: no oil pressure
Sent from my iPad
----x--O--x----
On 7 Oct 2016, at 02:51 pm, ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net) wrote:
| Quote: | Hi Ken;
Advice from an old electro-mechanical engineer (now 76) and new pilot ((at) 70): Keep the pilot in charge of turning things off.
Cheers! Stu.
From: "GTH" <gilles.thesee(at)free.fr (gilles.thesee(at)free.fr)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Friday, October 7, 2016 12:17:19 AM
Subject: Re: AeroElectric-List: rotax generator without battery
Le 07/10/2016 à 02:09, Ken Ryan a écrit :
| Quote: | I found this Pressure Switch which seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning.
|
Your call. You'll make your engine operation dependent on a switch and a relay.
"On a switch and a prayer"
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
|
|
|
|
|
|
|
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alec(at)alecmyers.com
Guest
|
| Posted: Fri Oct 07, 2016 3:32 pm Post subject: rotax generator without battery |
|
|
Rotax's advice to energize the backup pump for landing is based on limiting their own liability rather than improving your overall safety. Even if it's genuinely based on a concern for your safety then a pound to a penny the risk analysis on which they based that advice (if they did one) assumes 6000' tarmac strips and essentially no risk of inverting the aircraft with adequate pilot skill rather than rough bush operations.
Have you considered overriding their advice and leaving the pump off for landing?
On Oct 7, 2016, at 17:58, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Charlie,
The primary pump is powered by the integrated generator, so it already has auto shut off.
What are the odds? Well, in off airport operations here in Alaska the odds are probably higher than high altitude ops over midwest farm fields from one 6,000 foot paved runways to the next. I know more than one guy who has flipped his airplane, and they all say the same thing: it happened in an instant with no warning. Fortunately, they all walked away.
Ken
On Fri, Oct 7, 2016 at 1:41 PM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:
| Quote: | It really comes down to probability, modified by your personal risk tolerance. What are the odds of actually needing the auto-off function of the aux pump (remember that in t/o-landing modes the other pump will be running, too; what auto-protects that one?), vs the likelihood of needing the backup pump (primary failure) and risking any one of the various wires, connectors, pressure switch, pressure *line*, etc causing loss of the pump? Or actually *causing* a problem (pressure line or pressure switch opening an oil exit path comes to mind...).
In the 'simple' scenario, the aux pump switch mounted next to the primary pump switch allows one swipe to get both, if a crash is imminent.
But if the auto feature makes you more comfortable, go for it.
Charlie
On Fri, Oct 7, 2016 at 3:14 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | Alec,
I'm not sure where you got the idea that the auxiliary pump would be running all the time. It would indeed be used only for takeoffs and landings, via a toggle switch. But inserting the pressure switch and the relay would insure that in the event of a crash, such as on takeoff or landing, the auxiliary pump would automatically shut down when the engine ceases to turn (because the oil pressure would drop).
Ken
On Fri, Oct 7, 2016 at 11:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
That's very reasonable; why not just have an on-off switch for the backup pump? Switch it on on the ground to test, on for takeoff and landing and off the rest of the time.
Is there a benefit to having it run full time in parallel with the main pump? how do you tell if the main pump has failed if the backup is already running?
On Oct 7, 2016, at 15:19, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Rotax operating procedures for 914 call for running both electric fuel pumps for takeoff and landings.
On Fri, Oct 7, 2016 at 10:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
In that case why do you need the backup pump energised at all, absent a main fuel pump failure?
Many (most?) TC aircraft with fuel injection or low-wing tanks have an electric backup pump but it's either on only for takeoff and landing and switching tanks (Piper, Grumman) or only used for priming and in the event of engine storage due to main pump failure (Cessna)
I'm not familiar with the proposed system so If the backup pump is permanently energised what alerts the pilot to a failure of the engine-driven pump?
On Oct 7, 2016, at 12:27 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | I think maybe some of you are not factoring in that this is on the auxiliary fuel pump only. So for a failure of the switch or relay to have any effect on the flight, the main fuel pump would have already had to fail. The primary fuel pump stops automatically when the engine stops turning because it is powered off the generator.
As far as startup, I think the way the pressure switch works is that it is a single pole, double throw. So there are three terminals: Comm, L1, and L2. Without pressure, Comm is connected to L2. With pressure, Comm is connected to L1.
The Comm goes to the fuel pump relay.
L1 goes to a fuel pump switch.
L2 goes to the starter side of the starter relay.
So at startup, because the pressure switch without pressure is connected Comm-L2 only, closing the fuel pump switch would do nothing. But when cranking power is put to the starter, current would flow to the relay through the Comm-L2 connection. Then, when the engine starts and current is removed from the starter circuit, power continues to flow the fuel pump relay because now with 7lbs of oil pressure Comm is connected to L1 (and the switch has been turned on).
On Fri, Oct 7, 2016 at 7:30 AM, John Tipton <jmtipton(at)btopenworld.com (jmtipton(at)btopenworld.com)> wrote:
| Quote: | Q: how does the engine get it's fuel for start-up, the engine being off ie: no oil pressure
Sent from my iPad
----x--O--x----
On 7 Oct 2016, at 02:51 pm, ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net) wrote:
| Quote: | Hi Ken;
Advice from an old electro-mechanical engineer (now 76) and new pilot ((at) 70): Keep the pilot in charge of turning things off.
Cheers! Stu.
From: "GTH" <gilles.thesee(at)free.fr (gilles.thesee(at)free.fr)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Friday, October 7, 2016 12:17:19 AM
Subject: Re: rotax generator without battery
Le 07/10/2016 à 02:09, Ken Ryan a écrit :
| Quote: | I found this Pressure Switch which seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning.
|
Your call. You'll make your engine operation dependent on a switch and a relay.
"On a switch and a prayer"
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
|
|
|
|
|
|
|
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kenryan
Joined: 20 Oct 2009
Posts: 429
|
| Posted: Fri Oct 07, 2016 4:15 pm Post subject: rotax generator without battery |
|
|
Alec, Yes I have indeed considered that!
On Fri, Oct 7, 2016 at 3:30 PM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
Rotax's advice to energize the backup pump for landing is based on limiting their own liability rather than improving your overall safety. Even if it's genuinely based on a concern for your safety then a pound to a penny the risk analysis on which they based that advice (if they did one) assumes 6000' tarmac strips and essentially no risk of inverting the aircraft with adequate pilot skill rather than rough bush operations.
Have you considered overriding their advice and leaving the pump off for landing?
On Oct 7, 2016, at 17:58, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Charlie,
The primary pump is powered by the integrated generator, so it already has auto shut off.
What are the odds? Well, in off airport operations here in Alaska the odds are probably higher than high altitude ops over midwest farm fields from one 6,000 foot paved runways to the next. I know more than one guy who has flipped his airplane, and they all say the same thing: it happened in an instant with no warning. Fortunately, they all walked away.
Ken
On Fri, Oct 7, 2016 at 1:41 PM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:
| Quote: | It really comes down to probability, modified by your personal risk tolerance. What are the odds of actually needing the auto-off function of the aux pump (remember that in t/o-landing modes the other pump will be running, too; what auto-protects that one?), vs the likelihood of needing the backup pump (primary failure) and risking any one of the various wires, connectors, pressure switch, pressure *line*, etc causing loss of the pump? Or actually *causing* a problem (pressure line or pressure switch opening an oil exit path comes to mind...).
In the 'simple' scenario, the aux pump switch mounted next to the primary pump switch allows one swipe to get both, if a crash is imminent.
But if the auto feature makes you more comfortable, go for it.
Charlie
On Fri, Oct 7, 2016 at 3:14 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | Alec,
I'm not sure where you got the idea that the auxiliary pump would be running all the time. It would indeed be used only for takeoffs and landings, via a toggle switch. But inserting the pressure switch and the relay would insure that in the event of a crash, such as on takeoff or landing, the auxiliary pump would automatically shut down when the engine ceases to turn (because the oil pressure would drop).
Ken
On Fri, Oct 7, 2016 at 11:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
That's very reasonable; why not just have an on-off switch for the backup pump? Switch it on on the ground to test, on for takeoff and landing and off the rest of the time.
Is there a benefit to having it run full time in parallel with the main pump? how do you tell if the main pump has failed if the backup is already running?
On Oct 7, 2016, at 15:19, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
Rotax operating procedures for 914 call for running both electric fuel pumps for takeoff and landings.
On Fri, Oct 7, 2016 at 10:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)> wrote:
| Quote: |
In that case why do you need the backup pump energised at all, absent a main fuel pump failure?
Many (most?) TC aircraft with fuel injection or low-wing tanks have an electric backup pump but it's either on only for takeoff and landing and switching tanks (Piper, Grumman) or only used for priming and in the event of engine storage due to main pump failure (Cessna)
I'm not familiar with the proposed system so If the backup pump is permanently energised what alerts the pilot to a failure of the engine-driven pump?
On Oct 7, 2016, at 12:27 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | I think maybe some of you are not factoring in that this is on the auxiliary fuel pump only. So for a failure of the switch or relay to have any effect on the flight, the main fuel pump would have already had to fail. The primary fuel pump stops automatically when the engine stops turning because it is powered off the generator.
As far as startup, I think the way the pressure switch works is that it is a single pole, double throw. So there are three terminals: Comm, L1, and L2. Without pressure, Comm is connected to L2. With pressure, Comm is connected to L1.
The Comm goes to the fuel pump relay.
L1 goes to a fuel pump switch.
L2 goes to the starter side of the starter relay.
So at startup, because the pressure switch without pressure is connected Comm-L2 only, closing the fuel pump switch would do nothing. But when cranking power is put to the starter, current would flow to the relay through the Comm-L2 connection. Then, when the engine starts and current is removed from the starter circuit, power continues to flow the fuel pump relay because now with 7lbs of oil pressure Comm is connected to L1 (and the switch has been turned on).
On Fri, Oct 7, 2016 at 7:30 AM, John Tipton <jmtipton(at)btopenworld.com (jmtipton(at)btopenworld.com)> wrote:
| Quote: | Q: how does the engine get it's fuel for start-up, the engine being off ie: no oil pressure
Sent from my iPad
----x--O--x----
On 7 Oct 2016, at 02:51 pm, ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net) wrote:
| Quote: | Hi Ken;
Advice from an old electro-mechanical engineer (now 76) and new pilot ((at) 70): Keep the pilot in charge of turning things off.
Cheers! Stu.
From: "GTH" <gilles.thesee(at)free.fr (gilles.thesee(at)free.fr)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Friday, October 7, 2016 12:17:19 AM
Subject: Re: rotax generator without battery
Le 07/10/2016 à 02:09, Ken Ryan a écrit :
| Quote: | I found this Pressure Switch which seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning.
|
Your call. You'll make your engine operation dependent on a switch and a relay.
"On a switch and a prayer"
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
|
|
|
|
|
|
|
|
| | - The Matronics AeroElectric-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?AeroElectric-List |
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raymondj(at)frontiernet.n
Guest
|
| Posted: Fri Oct 07, 2016 4:32 pm Post subject: rotax generator without battery |
|
|
I agree with Ken's analysis. Several scenarios where the auto shutoff
would be a benefit: Snag a wheel and invert on t/o or landing;
Challenging cross wind landing goes bad; Failure to clear and obstacle
on t/o or landing; Bird strike; Deer strike; Encounter with
extraterrestrial beings; and the ever popular item with insurance
companies -Act of God-.
If it were my aircraft, I'd put in an 'engine not in operation'
detection system of some sort. Oil pressure switches have a long
history of reliable operation in the field. The only issue I see is
verifying the system is functioning properly during preflight/startup.
Raymond Julian
Kettle River, MN
The things we admire in men, kindness and generosity, openness, honesty,
understanding and feeling are the concomitants of failure in our system.
And those traits we detest, sharpness, greed, acquisitiveness, meanness,
egotism and self-interest are the traits of success. And while men
admire the quality of the first they love the produce of the second.
-John Steinbeck, novelist, Nobel laureate (1902-1968)
On 10/07/2016 04:58 PM, Ken Ryan wrote:
| Quote: | Charlie,
The primary pump is powered by the integrated generator, so it already
has auto shut off.
What are the odds? Well, in off airport operations here in Alaska the
odds are probably higher than high altitude ops over midwest farm fields
from one 6,000 foot paved runways to the next. I know more than one guy
who has flipped his airplane, and they all say the same thing: it
happened in an instant with no warning. Fortunately, they all walked away.
Ken
On Fri, Oct 7, 2016 at 1:41 PM, Charlie England <ceengland7(at)gmail.com
<mailto:ceengland7(at)gmail.com>> wrote:
It really comes down to probability, modified by your personal risk
tolerance. What are the odds of actually needing the auto-off
function of the aux pump (remember that in t/o-landing modes the
other pump will be running, too; what auto-protects that one?), vs
the likelihood of needing the backup pump (primary failure) and
risking any one of the various wires, connectors, pressure switch,
pressure *line*, etc causing loss of the pump? Or actually *causing*
a problem (pressure line or pressure switch opening an oil exit path
comes to mind...).
In the 'simple' scenario, the aux pump switch mounted next to the
primary pump switch allows one swipe to get both, if a crash is
imminent.
But if the auto feature makes you more comfortable, go for it.
Charlie
On Fri, Oct 7, 2016 at 3:14 PM, Ken Ryan <keninalaska(at)gmail.com
<mailto:keninalaska(at)gmail.com>> wrote:
Alec,
I'm not sure where you got the idea that the auxiliary pump
would be running all the time. It would indeed be used only for
takeoffs and landings, via a toggle switch. But inserting the
pressure switch and the relay would insure that in the event of
a crash, such as on takeoff or landing, the auxiliary pump would
automatically shut down when the engine ceases to turn (because
the oil pressure would drop).
Ken
On Fri, Oct 7, 2016 at 11:59 AM, Alec Myers <alec(at)alecmyers.com
<mailto:alec(at)alecmyers.com>> wrote:
That's very reasonable; why not just have an on-off switch
for the backup pump? Switch it on on the ground to test, on
for takeoff and landing and off the rest of the time.
Is there a benefit to having it run full time in parallel
with the main pump? how do you tell if the main pump has
failed if the backup is already running?
On Oct 7, 2016, at 15:19, Ken Ryan <keninalaska(at)gmail.com
<mailto:keninalaska(at)gmail.com>> wrote:
Rotax operating procedures for 914 call for running both
electric fuel pumps for takeoff and landings.
On Fri, Oct 7, 2016 at 10:59 AM, Alec Myers
<alec(at)alecmyers.com <mailto:alec(at)alecmyers.com>> wrote:
In that case why do you need the backup pump energised
at all, absent a main fuel pump failure?
Many (most?) TC aircraft with fuel injection or low-wing
tanks have an electric backup pump but it's either on
only for takeoff and landing and switching tanks (Piper,
Grumman) or only used for priming and in the event of
engine storage due to main pump failure (Cessna)
I'm not familiar with the proposed system so If the
backup pump is permanently energised what alerts the
pilot to a failure of the engine-driven pump?
On Oct 7, 2016, at 12:27 PM, Ken Ryan
<keninalaska(at)gmail.com <mailto:keninalaska(at)gmail.com>>
wrote:
> I think maybe some of you are not factoring in that
> this is on the auxiliary fuel pump only. So for a
> failure of the switch or relay to have any effect on
> the flight, the main fuel pump would have already had
> to fail. The primary fuel pump stops automatically
> when the engine stops turning because it is powered
> off the generator.
>
> As far as startup, I think the way the pressure switch
> works is that it is a single pole, double throw. So
> there are three terminals: Comm, L1, and L2. Without
> pressure, Comm is connected to L2. With pressure, Comm
> is connected to L1.
>
> The Comm goes to the fuel pump relay.
> L1 goes to a fuel pump switch.
> L2 goes to the starter side of the starter relay.
>
> So at startup, because the pressure switch without
> pressure is connected Comm-L2 only, closing the fuel
> pump switch would do nothing. But when cranking power
> is put to the starter, current would flow to the relay
> through the Comm-L2 connection. Then, when the engine
> starts and current is removed from the starter
> circuit, power continues to flow the fuel pump relay
> because now with 7lbs of oil pressure Comm is
> connected to L1 (and the switch has been turned on).
>
> On Fri, Oct 7, 2016 at 7:30 AM, John Tipton
> <jmtipton(at)btopenworld.com
> <mailto:jmtipton(at)btopenworld.com>> wrote:
>
> Q: how does the engine get it's fuel for start-up,
> the engine being off ie: no oil pressure
>
> Sent from my iPad
>
> ----x--O--x----
>
> On 7 Oct 2016, at 02:51 pm,
> ashleysc(at)broadstripe.net
> <mailto:ashleysc(at)broadstripe.net> wrote:
>
>> Hi Ken;
>> Advice from an old electro-mechanical engineer
>> (now 76) and new pilot ((at) 70): Keep the pilot in
>> charge of turning things off.
>> Cheers! Stu.
>>
>> ------------------------------------------------------------------------
>> *From: *"GTH" <gilles.thesee(at)free.fr
>> <mailto:gilles.thesee(at)free.fr>>
>> *To: *aeroelectric-list(at)matronics.com
>> <mailto:aeroelectric-list(at)matronics.com>
>> *Sent: *Friday, October 7, 2016 12:17:19 AM
>> *Subject: *Re: rotax generator
>> without battery
>>
>> /Le 07/10/2016 à 02:09, Ken Ryan a écrit :
>> /
>>
>> /I found this Pressure Switch
>> <https://www.summitracing.com/parts/crt-a68301> which
>> seems to be a viable way (combined with a
>> relay) of automatically turning off the
>> auxiliary fuel pump when the engine stops
>> turning./
>>
>>
>> Your call. You'll make your engine operation
>> dependent on a switch and a relay.
>> "On a switch and a prayer"
>> --
>> Best regards,
>> Gilles
>> http://contrails.free.fr
>> http://lapierre.skunkworks.free.fr
>> <http://lapierre.skunkworks.free.fr>
>>
>
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Fri Oct 07, 2016 7:17 pm Post subject: rotax generator without battery |
|
|
At 02:17 AM 10/7/2016, you wrote:
| Quote: | Le 07/10/2016 02:09, Ken Ryan a écrit :
| Quote: | | I found this Pressure Switch which seems to be a viable way (combined with a relay) of automatically turning off the auxiliary fuel pump when the engine stops turning. |
Your call. You'll make your engine operation dependent on a switch and a relay.
"On a switch and a prayer" |
How so? If there are TWO pumps with independent
power paths, then the holy grail of FMEA has
been achieved. "No single failure" of the
electrically driven fuel delivery system
will disable the engine.
In conducting an FMEA you assume that EVERY
part . . . crimped terminals, threaded fasteners,
circuit breaker, switch, relay, etc. etc. WILL
fail. Then configure a system whereby that failure
does not put the airplane at risk. See chapter 17
of the 'Connection.
Bob . . .
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kenryan
Joined: 20 Oct 2009
Posts: 429
|
| Posted: Fri Oct 07, 2016 9:53 pm Post subject: rotax generator without battery |
|
|
Raymond,
I don't see a problem verifying that the system is functioning properly. Startup procedure would be:
1. Flip auxiliary fuel pump switch on (nothing happens)
2. Engage starter (simultaneously sends power to the aux pump)
3. Oil pressure rises, engine starts
4. Starter is disengaged
5. Engine continues to run
At this point the auxiliary fuel system has been checked. All that remains is to power up the main fuel pump and then turn off the aux pump. If the engine continues to run, the main fuel pump check out.
Incidentally, it turns out that no relay is necessary. The pressure switch is adequately rated for the pump current.
Ken
On Fri, Oct 7, 2016 at 4:30 PM, rayj <raymondj(at)frontiernet.net (raymondj(at)frontiernet.net)> wrote:
| Quote: | --> AeroElectric-List message posted by: rayj <raymondj(at)frontiernet.net (raymondj(at)frontiernet.net)>
I agree with Ken's analysis. Several scenarios where the auto shutoff would be a benefit: Snag a wheel and invert on t/o or landing; Challenging cross wind landing goes bad; Failure to clear and obstacle on t/o or landing; Bird strike; Deer strike; Encounter with extraterrestrial beings; and the ever popular item with insurance companies -Act of God-.
If it were my aircraft, I'd put in an 'engine not in operation' detection system of some sort. Oil pressure switches have a long history of reliable operation in the field. The only issue I see is verifying the system is functioning properly during preflight/startup.
Raymond Julian
Kettle River, MN
The things we admire in men, kindness and generosity, openness, honesty, understanding and feeling are the concomitants of failure in our system. And those traits we detest, sharpness, greed, acquisitiveness, meanness, egotism and self-interest are the traits of success. And while men admire the quality of the first they love the produce of the second. -John Steinbeck, novelist, Nobel laureate (1902-1968)
On 10/07/2016 04:58 PM, Ken Ryan wrote:
| Quote: | Charlie,
The primary pump is powered by the integrated generator, so it already
has auto shut off.
What are the odds? Well, in off airport operations here in Alaska the
odds are probably higher than high altitude ops over midwest farm fields
from one 6,000 foot paved runways to the next. I know more than one guy
who has flipped his airplane, and they all say the same thing: it
happened in an instant with no warning. Fortunately, they all walked away.
Ken
On Fri, Oct 7, 2016 at 1:41 PM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)
<mailto:ceengland7(at)gmail.com (ceengland7(at)gmail.com)>> wrote:
It really comes down to probability, modified by your personal risk
tolerance. What are the odds of actually needing the auto-off
function of the aux pump (remember that in t/o-landing modes the
other pump will be running, too; what auto-protects that one?), vs
the likelihood of needing the backup pump (primary failure) and
risking any one of the various wires, connectors, pressure switch,
pressure *line*, etc causing loss of the pump? Or actually *causing*
a problem (pressure line or pressure switch opening an oil exit path
comes to mind...).
In the 'simple' scenario, the aux pump switch mounted next to the
primary pump switch allows one swipe to get both, if a crash is
imminent.
But if the auto feature makes you more comfortable, go for it.
Charlie
On Fri, Oct 7, 2016 at 3:14 PM, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)
<mailto:keninalaska(at)gmail.com (keninalaska(at)gmail.com)>> wrote:
Alec,
I'm not sure where you got the idea that the auxiliary pump
would be running all the time. It would indeed be used only for
takeoffs and landings, via a toggle switch. But inserting the
pressure switch and the relay would insure that in the event of
a crash, such as on takeoff or landing, the auxiliary pump would
automatically shut down when the engine ceases to turn (because
the oil pressure would drop).
Ken
On Fri, Oct 7, 2016 at 11:59 AM, Alec Myers <alec(at)alecmyers.com (alec(at)alecmyers.com)
<mailto:alec(at)alecmyers.com (alec(at)alecmyers.com)>> wrote:
That's very reasonable; why not just have an on-off switch
for the backup pump? Switch it on on the ground to test, on
for takeoff and landing and off the rest of the time.
Is there a benefit to having it run full time in parallel
with the main pump? how do you tell if the main pump has
failed if the backup is already running?
On Oct 7, 2016, at 15:19, Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)
<mailto:keninalaska(at)gmail.com (keninalaska(at)gmail.com)>> wrote:
Rotax operating procedures for 914 call for running both
electric fuel pumps for takeoff and landings.
On Fri, Oct 7, 2016 at 10:59 AM, Alec Myers
<alec(at)alecmyers.com (alec(at)alecmyers.com) <mailto:alec(at)alecmyers.com (alec(at)alecmyers.com)>> wrote:
In that case why do you need the backup pump energised
at all, absent a main fuel pump failure?
Many (most?) TC aircraft with fuel injection or low-wing
tanks have an electric backup pump but it's either on
only for takeoff and landing and switching tanks (Piper,
Grumman) or only used for priming and in the event of
engine storage due to main pump failure (Cessna)
I'm not familiar with the proposed system so If the
backup pump is permanently energised what alerts the
pilot to a failure of the engine-driven pump?
On Oct 7, 2016, at 12:27 PM, Ken Ryan
<keninalaska(at)gmail.com (keninalaska(at)gmail.com) <mailto:keninalaska(at)gmail.com (keninalaska(at)gmail.com)>>
wrote:
| Quote: | I think maybe some of you are not factoring in that
this is on the auxiliary fuel pump only. So for a
failure of the switch or relay to have any effect on
the flight, the main fuel pump would have already had
to fail. The primary fuel pump stops automatically
when the engine stops turning because it is powered
off the generator.
As far as startup, I think the way the pressure switch
works is that it is a single pole, double throw. So
there are three terminals: Comm, L1, and L2. Without
pressure, Comm is connected to L2. With pressure, Comm
is connected to L1.
The Comm goes to the fuel pump relay.
L1 goes to a fuel pump switch.
L2 goes to the starter side of the starter relay.
So at startup, because the pressure switch without
pressure is connected Comm-L2 only, closing the fuel
pump switch would do nothing. But when cranking power
is put to the starter, current would flow to the relay
through the Comm-L2 connection. Then, when the engine
starts and current is removed from the starter
circuit, power continues to flow the fuel pump relay
because now with 7lbs of oil pressure Comm is
connected to L1 (and the switch has been turned on).
On Fri, Oct 7, 2016 at 7:30 AM, John Tipton
<jmtipton(at)btopenworld.com (jmtipton(at)btopenworld.com)
<mailto:jmtipton(at)btopenworld.com (jmtipton(at)btopenworld.com)>> wrote:
Q: how does the engine get it's fuel for start-up,
the engine being off ie: no oil pressure
Sent from my iPad
----x--O--x----
On 7 Oct 2016, at 02:51 pm,
ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net)
<mailto:ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net)> wrote:
|
|
====================================
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errer" target="_blank">http://wiki.matronics.com
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rel="noreferrer" target="_blank">http://www.matronics.com/contribution
====================================
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raymondj(at)frontiernet.n
Guest
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| Posted: Fri Oct 07, 2016 11:38 pm Post subject: rotax generator without battery |
|
|
I didn't catch that the primary pump was switchable. I made the mistake
of assuming that it was wired direct to the engine driven power supply
(a la a mechanical pump). Sounds foolish now that I see it in print.
As long as the battery can crank the engine long enough to pressurize
the oil system sufficiently, is should work. Or, you could start with
the primary, and immediately switch to aux pump for ground operations,
then both on takeoff. I'm sure with a little T&E it can be worked out.
Raymond Julian
Kettle River, MN
The things we admire in men, kindness and generosity, openness, honesty,
understanding and feeling are the concomitants of failure in our system.
And those traits we detest, sharpness, greed, acquisitiveness, meanness,
egotism and self-interest are the traits of success. And while men
admire the quality of the first they love the produce of the second.
-John Steinbeck, novelist, Nobel laureate (1902-1968)
On 10/07/2016 11:44 PM, Ken Ryan wrote:
| Quote: | Raymond,
I don't see a problem verifying that the system is functioning properly.
Startup procedure would be:
1. Flip auxiliary fuel pump switch on (nothing happens)
2. Engage starter (simultaneously sends power to the aux pump)
3. Oil pressure rises, engine starts
4. Starter is disengaged
5. Engine continues to run
At this point the auxiliary fuel system has been checked. All that
remains is to power up the main fuel pump and then turn off the aux
pump. If the engine continues to run, the main fuel pump check out.
Incidentally, it turns out that no relay is necessary. The pressure
switch is adequately rated for the pump current.
Ken
On Fri, Oct 7, 2016 at 4:30 PM, rayj <raymondj(at)frontiernet.net
<mailto:raymondj(at)frontiernet.net>> wrote:
<raymondj(at)frontiernet.net <mailto:raymondj(at)frontiernet.net>>
I agree with Ken's analysis. Several scenarios where the auto
shutoff would be a benefit: Snag a wheel and invert on t/o or
landing; Challenging cross wind landing goes bad; Failure to clear
and obstacle on t/o or landing; Bird strike; Deer strike;
Encounter with extraterrestrial beings; and the ever popular item
with insurance companies -Act of God-.
If it were my aircraft, I'd put in an 'engine not in operation'
detection system of some sort. Oil pressure switches have a long
history of reliable operation in the field. The only issue I see is
verifying the system is functioning properly during preflight/startup.
Raymond Julian
Kettle River, MN
The things we admire in men, kindness and generosity, openness,
honesty, understanding and feeling are the concomitants of failure
in our system. And those traits we detest, sharpness, greed,
acquisitiveness, meanness, egotism and self-interest are the traits
of success. And while men admire the quality of the first they love
the produce of the second. -John Steinbeck, novelist, Nobel laureate
(1902-1968)
On 10/07/2016 04:58 PM, Ken Ryan wrote:
Charlie,
The primary pump is powered by the integrated generator, so it
already
has auto shut off.
What are the odds? Well, in off airport operations here in
Alaska the
odds are probably higher than high altitude ops over midwest
farm fields
from one 6,000 foot paved runways to the next. I know more than
one guy
who has flipped his airplane, and they all say the same thing: it
happened in an instant with no warning. Fortunately, they all
walked away.
Ken
On Fri, Oct 7, 2016 at 1:41 PM, Charlie England
<ceengland7(at)gmail.com <mailto:ceengland7(at)gmail.com>
<mailto:ceengland7(at)gmail.com <mailto:ceengland7(at)gmail.com>>> wrote:
It really comes down to probability, modified by your
personal risk
tolerance. What are the odds of actually needing the auto-off
function of the aux pump (remember that in t/o-landing modes the
other pump will be running, too; what auto-protects that
one?), vs
the likelihood of needing the backup pump (primary failure) and
risking any one of the various wires, connectors, pressure
switch,
pressure *line*, etc causing loss of the pump? Or actually
*causing*
a problem (pressure line or pressure switch opening an oil
exit path
comes to mind...).
In the 'simple' scenario, the aux pump switch mounted next
to the
primary pump switch allows one swipe to get both, if a crash is
imminent.
But if the auto feature makes you more comfortable, go for it.
Charlie
On Fri, Oct 7, 2016 at 3:14 PM, Ken Ryan
<keninalaska(at)gmail.com <mailto:keninalaska(at)gmail.com>
<mailto:keninalaska(at)gmail.com
<mailto:keninalaska(at)gmail.com>>> wrote:
Alec,
I'm not sure where you got the idea that the auxiliary pump
would be running all the time. It would indeed be used
only for
takeoffs and landings, via a toggle switch. But
inserting the
pressure switch and the relay would insure that in the
event of
a crash, such as on takeoff or landing, the auxiliary
pump would
automatically shut down when the engine ceases to turn
(because
the oil pressure would drop).
Ken
On Fri, Oct 7, 2016 at 11:59 AM, Alec Myers
<alec(at)alecmyers.com <mailto:alec(at)alecmyers.com>
<mailto:alec(at)alecmyers.com <mailto:alec(at)alecmyers.com>>>
wrote:
That's very reasonable; why not just have an on-off
switch
for the backup pump? Switch it on on the ground to
test, on
for takeoff and landing and off the rest of the time.
Is there a benefit to having it run full time in
parallel
with the main pump? how do you tell if the main pump has
failed if the backup is already running?
On Oct 7, 2016, at 15:19, Ken Ryan
<keninalaska(at)gmail.com <mailto:keninalaska(at)gmail.com>
<mailto:keninalaska(at)gmail.com
<mailto:keninalaska(at)gmail.com>>> wrote:
Rotax operating procedures for 914 call for running both
electric fuel pumps for takeoff and landings.
On Fri, Oct 7, 2016 at 10:59 AM, Alec Myers
<alec(at)alecmyers.com <mailto:alec(at)alecmyers.com>
<mailto:alec(at)alecmyers.com <mailto:alec(at)alecmyers.com>>> wrote:
In that case why do you need the backup pump
energised
at all, absent a main fuel pump failure?
Many (most?) TC aircraft with fuel injection or
low-wing
tanks have an electric backup pump but it's
either on
only for takeoff and landing and switching tanks
(Piper,
Grumman) or only used for priming and in the
event of
engine storage due to main pump failure (Cessna)
I'm not familiar with the proposed system so If the
backup pump is permanently energised what alerts the
pilot to a failure of the engine-driven pump?
On Oct 7, 2016, at 12:27 PM, Ken Ryan
<keninalaska(at)gmail.com
<mailto:keninalaska(at)gmail.com> <mailto:keninalaska(at)gmail.com
<mailto:keninalaska(at)gmail.com>>>
wrote:
I think maybe some of you are not factoring
in that
this is on the auxiliary fuel pump only. So
for a
failure of the switch or relay to have any
effect on
the flight, the main fuel pump would have
already had
to fail. The primary fuel pump stops
automatically
when the engine stops turning because it is
powered
off the generator.
As far as startup, I think the way the
pressure switch
works is that it is a single pole, double
throw. So
there are three terminals: Comm, L1, and L2.
Without
pressure, Comm is connected to L2. With
pressure, Comm
is connected to L1.
The Comm goes to the fuel pump relay.
L1 goes to a fuel pump switch.
L2 goes to the starter side of the starter
relay.
So at startup, because the pressure switch
without
pressure is connected Comm-L2 only, closing
the fuel
pump switch would do nothing. But when
cranking power
is put to the starter, current would flow to
the relay
through the Comm-L2 connection. Then, when
the engine
starts and current is removed from the starter
circuit, power continues to flow the fuel
pump relay
because now with 7lbs of oil pressure Comm is
connected to L1 (and the switch has been
turned on).
On Fri, Oct 7, 2016 at 7:30 AM, John Tipton
<jmtipton(at)btopenworld.com
<mailto:jmtipton(at)btopenworld.com>
<mailto:jmtipton(at)btopenworld.com
<mailto:jmtipton(at)btopenworld.com>>> wrote:
Q: how does the engine get it's fuel for
start-up,
the engine being off ie: no oil pressure
Sent from my iPad
----x--O--x----
On 7 Oct 2016, at 02:51 pm,
ashleysc(at)broadstripe.net
<mailto:ashleysc(at)broadstripe.net>
<mailto:ashleysc(at)broadstripe.net
<mailto:ashleysc(at)broadstripe.net>> wrote:
Hi Ken;
Advice from an old
electro-mechanical engineer
(now 76) and new pilot ((at) 70): Keep
the pilot in
charge of turning things off.
Cheers! Stu.
------------------------------------------------------------------------
*From: *"GTH" <gilles.thesee(at)free.fr
<mailto:gilles.thesee(at)free.fr>
<mailto:gilles.thesee(at)free.fr
<mailto:gilles.thesee(at)free.fr>>>
*To:
*aeroelectric-list(at)matronics.com
<mailto:aeroelectric-list(at)matronics.com>
<mailto:aeroelectric-list(at)matronics.com
<mailto:aeroelectric-list(at)matronics.com>>
*Sent: *Friday, October 7, 2016
12:17:19 AM
*Subject: *Re: AeroElectric-List:
rotax generator
without battery
/Le 07/10/2016 à 02:09, Ken Ryan a
écrit :
/
/I found this Pressure Switch
<https://www.summitracing.com/parts/crt-a68301
<https://www.summitracing.com/parts/crt-a68301>> which
seems to be a viable way
(combined with a
relay) of automatically turning
off the
auxiliary fuel pump when the
engine stops
turning./
Your call. You'll make your engine
operation
dependent on a switch and a relay.
"On a switch and a prayer"
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
<http://lapierre.skunkworks.free.fr>
<http://lapierre.skunkworks.free.fr
<http://lapierre.skunkworks.free.fr>>
====================================
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Electric-List" rel="noreferrer"
target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
====================================
FORUMS -
eferrer" target="_blank">http://forums.matronics.com
====================================
WIKI -
errer" target="_blank">http://wiki.matronics.com
====================================
b Site -
-Matt Dralle, List Admin.
rel="noreferrer" target="_blank">http://www.matronics.com/contribution
====================================
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