---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 10/07/16: 17 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:22 AM - Re: rotax generator without battery (GTH) 2. 07:07 AM - Re: rotax generator without battery (ashleysc@broadstripe.net) 3. 08:33 AM - Re: rotax generator without battery (John Tipton) 4. 09:21 AM - Skyview Screens and Z13/8 (Jared Yates) 5. 09:29 AM - Re: rotax generator without battery (Ken Ryan) 6. 09:43 AM - Re: Skyview Screens and Z13/8 (Sebastien) 7. 12:01 PM - Re: rotax generator without battery (Alec Myers) 8. 12:21 PM - Re: rotax generator without battery (Ken Ryan) 9. 01:01 PM - Re: rotax generator without battery (Alec Myers) 10. 01:17 PM - Re: rotax generator without battery (Ken Ryan) 11. 02:43 PM - Re: rotax generator without battery (Charlie England) 12. 03:01 PM - Re: rotax generator without battery (Ken Ryan) 13. 04:33 PM - Re: rotax generator without battery (Alec Myers) 14. 05:15 PM - Re: rotax generator without battery (Ken Ryan) 15. 05:33 PM - Re: rotax generator without battery (rayj) 16. 08:17 PM - Re: rotax generator without battery (Robert L. Nuckolls, III) 17. 10:53 PM - Re: rotax generator without battery (Ken Ryan) ________________________________ Message 1 _____________________________________ Time: 12:22:02 AM PST US Subject: Re: AeroElectric-List: rotax generator without battery From: GTH /Le 07/10/2016 02:09, Ken Ryan a crit : / > /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 ________________________________ Message 2 _____________________________________ Time: 07:07:03 AM PST US From: ashleysc@broadstripe.net Subject: Re: AeroElectric-List: rotax generator without battery Hi Ken; Advice from an old electro-mechanical engineer (now 76) and new pilot (@ 70 ): Keep the pilot in charge of turning things off. Cheers! Stu. ----- Original Message ----- From: "GTH" Sent: Friday, October 7, 2016 12:17:19 AM Subject: Re: AeroElectric-List: rotax generator without battery Le 07/10/2016 =C3- 02:09, Ken Ryan a =C3=A9crit : 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 engi ne stops turning. Your call. You'll make your engine operation dependent on a switch and a re lay. "On a switch and a prayer" ;-) -- Best regards, Gilles http://contrails.free.fr http://lapierre.skunkworks.free.fr ________________________________ Message 3 _____________________________________ Time: 08:33:03 AM PST US Subject: Re: AeroElectric-List: rotax generator without battery From: John Tipton Q: how does the engine get it's fuel for start-up, the engine being off ie: n o oil pressure Sent from my iPad ----x--O--x---- > On 7 Oct 2016, at 02:51 pm, ashleysc@broadstripe.net wrote: > > Hi Ken; > Advice from an old electro-mechanical engineer (now 76) and new pilot (@ 7 0): Keep the pilot in charge of turning things off. > Cheers! Stu. > > From: "GTH" > To: aeroelectric-list@matronics.com > Sent: Friday, October 7, 2016 12:17:19 AM > Subject: Re: AeroElectric-List: rotax generator without battery > > Le 07/10/2016 =C3- 02:09, Ken Ryan a =C3=A9crit : > 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 engi ne stops turning. > > Your call. You'll make your engine operation dependent on a switch and a r elay. > "On a switch and a prayer" ;-) > -- > Best regards, > Gilles > http://contrails.free.fr > http://lapierre.skunkworks.free.fr > ________________________________ Message 4 _____________________________________ Time: 09:21:06 AM PST US From: Jared Yates Subject: AeroElectric-List: Skyview Screens and Z13/8 I'm considering installation of a Dynon Skyview system with two 7" screens, and wondering how to best power them. I've got plenty of room on the ebus from a load analysis standpoint, but is it better to put one screen on the main bus in case the ebus were to short? Is there any issue with having a half volt difference powering the two screens? How has everyone else been doing it? ________________________________ Message 5 _____________________________________ Time: 09:29:52 AM PST US From: Ken Ryan Subject: Re: AeroElectric-List: rotax generator without battery 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 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@broadstripe.net wrote: > > Hi Ken; > Advice from an old electro-mechanical engineer (now 76) and new pilot (@ > 70): Keep the pilot in charge of turning things off. > Cheers! Stu. > > ------------------------------ > *From: *"GTH" > *To: *aeroelectric-list@matronics.com > *Sent: *Friday, October 7, 2016 12:17:19 AM > *Subject: *Re: AeroElectric-List: rotax generator without battery > > > *Le 07/10/2016 =C3- 02:09, Ken Ryan a =C3=A9crit : * > > *I found this Pressure Switch > which seems to be a viabl e > way (combined with a relay) of automatically turning off the auxiliary fu el > 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 > > ________________________________ Message 6 _____________________________________ Time: 09:43:31 AM PST US From: Sebastien Subject: Re: AeroElectric-List: Skyview Screens and Z13/8 My understanding is you only put what you need to safely conclude the flight on the ebus so primary EFIS only. I would also highly recommend you put both screens on the pilot side so that if one fails, the other one is in front of you, not the passenger. On Fri, Oct 7, 2016 at 9:17 AM, Jared Yates wrote: > I'm considering installation of a Dynon Skyview system with two 7" > screens, and wondering how to best power them. I've got plenty of room on > the ebus from a load analysis standpoint, but is it better to put one > screen on the main bus in case the ebus were to short? Is there any issue > with having a half volt difference powering the two screens? How has > everyone else been doing it? > ________________________________ Message 7 _____________________________________ Time: 12:01:43 PM PST US From: Alec Myers Subject: Re: AeroElectric-List: rotax generator without battery 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 elect ric backup pump but it's either on only for takeoff and landing and switchin g 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 permanent ly energised what alerts the pilot to a failure of the engine-driven pump? > On Oct 7, 2016, at 12:27 PM, Ken Ryan wrote: > > I think maybe some of you are not factoring in that this is on the auxilia ry fuel pump only. So for a failure of the switch or relay to have any effec t on the flight, the main fuel pump would have already had to fail. The prim ary fuel pump stops automatically when the engine stops turning because it i s 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 connecte d 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 C omm-L2 only, closing the fuel pump switch would do nothing. But when crankin g power is put to the starter, current would flow to the relay through the C omm-L2 connection. Then, when the engine starts and current is removed from t he starter circuit, power continues to flow the fuel pump relay because now w ith 7lbs of oil pressure Comm is connected to L1 (and the switch has been tu rned on). > > > >> On Fri, Oct 7, 2016 at 7:30 AM, John Tipton wr ote: >> Q: how does the engine get it's fuel for start-up, the engine being off i e: no oil pressure >> >> Sent from my iPad >> >> ----x--O--x---- >> >>> On 7 Oct 2016, at 02:51 pm, ashleysc@broadstripe.net wrote: >>> >>> Hi Ken; >>> Advice from an old electro-mechanical engineer (now 76) and new pilot (@ 70): Keep the pilot in charge of turning things off. >>> Cheers! Stu. >>> >>> From: "GTH" >>> To: aeroelectric-list@matronics.com >>> Sent: Friday, October 7, 2016 12:17:19 AM >>> Subject: Re: AeroElectric-List: rotax generator without battery >>> >>> Le 07/10/2016 =C3- 02:09, Ken Ryan a =C3=A9crit : >>> I found this Pressure Switch which seems to be a viable way (combined wi th a relay) of automatically turning off the auxiliary fuel pump when the en gine 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 >>> > ________________________________ Message 8 _____________________________________ Time: 12:21:59 PM PST US From: Ken Ryan Subject: Re: AeroElectric-List: rotax generator without battery 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 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 even t > 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 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 i s > 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 > 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@broadstripe.net wrote: >> >> Hi Ken; >> Advice from an old electro-mechanical engineer (now 76) and new pilot (@ >> 70): Keep the pilot in charge of turning things off. >> Cheers! Stu. >> >> ------------------------------ >> *From: *"GTH" >> *To: *aeroelectric-list@matronics.com >> *Sent: *Friday, October 7, 2016 12:17:19 AM >> *Subject: *Re: AeroElectric-List: rotax generator without battery >> >> >> *Le 07/10/2016 =C3- 02:09, Ken Ryan a =C3=A9crit : * >> >> *I found this Pressure Switch >> which seems to be a viab le >> way (combined with a relay) of automatically turning off the auxiliary f uel >> 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 >> >> > ________________________________ Message 9 _____________________________________ Time: 01:01:55 PM PST US From: Alec Myers Subject: Re: AeroElectric-List: rotax generator without battery That's very reasonable; why not just have an on-off switch for the backup pu mp? Switch it on on the ground to test, on for takeoff and landing and off t he rest of the time. Is there a benefit to having it run full time in parallel with the main pum p? how do you tell if the main pump has failed if the backup is already runn ing? On Oct 7, 2016, at 15:19, Ken Ryan 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 wrote: > In that case why do you need the backup pump energised at all, absent a ma in fuel pump failure? > > Many (most?) TC aircraft with fuel injection or low-wing tanks have an ele ctric backup pump but it's either on only for takeoff and landing and switch ing tanks (Piper, Grumman) or only used for priming and in the event of engi ne storage due to main pump failure (Cessna) > > I'm not familiar with the proposed system so If the backup pump is permane ntly energised what alerts the pilot to a failure of the engine-driven pump? > > >> On Oct 7, 2016, at 12:27 PM, Ken Ryan wrote: >> >> I think maybe some of you are not factoring in that this is on the auxili ary fuel pump only. So for a failure of the switch or relay to have any effe ct on the flight, the main fuel pump would have already had to fail. The pri mary fuel pump stops automatically when the engine stops turning because it i s powered off the generator. >> >> As far as startup, I think the way the pressure switch works is that it i s a single pole, double throw. So there are three terminals: Comm, L1, and L 2. Without pressure, Comm is connected to L2. With pressure, Comm is connect ed 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 C omm-L2 only, closing the fuel pump switch would do nothing. But when crankin g power is put to the starter, current would flow to the relay through the C omm-L2 connection. Then, when the engine starts and current is removed from t he starter circuit, power continues to flow the fuel pump relay because now w ith 7lbs of oil pressure Comm is connected to L1 (and the switch has been tu rned on). >> >> >> >>> On Fri, Oct 7, 2016 at 7:30 AM, John Tipton w rote: >>> Q: how does the engine get it's fuel for start-up, the engine being off i e: no oil pressure >>> >>> Sent from my iPad >>> >>> ----x--O--x---- >>> >>>> On 7 Oct 2016, at 02:51 pm, ashleysc@broadstripe.net wrote: >>>> >>>> Hi Ken; >>>> Advice from an old electro-mechanical engineer (now 76) and new pilot ( @ 70): Keep the pilot in charge of turning things off. >>>> Cheers! Stu. >>>> >>>> From: "GTH" >>>> To: aeroelectric-list@matronics.com >>>> Sent: Friday, October 7, 2016 12:17:19 AM >>>> Subject: Re: AeroElectric-List: rotax generator without battery >>>> >>>> Le 07/10/2016 =C3- 02:09, Ken Ryan a =C3=A9crit : >>>> I found this Pressure Switch which seems to be a viable way (combined w ith a relay) of automatically turning off the auxiliary fuel pump when the e ngine 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 >>>> >> ________________________________ Message 10 ____________________________________ Time: 01:17:12 PM PST US From: Ken Ryan Subject: Re: AeroElectric-List: rotax generator without battery 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 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 alread y > running? > > > On Oct 7, 2016, at 15:19, Ken Ryan 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 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 eve nt >> 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 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 hav e >> 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 >> 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@broadstripe.net wrote: >>> >>> Hi Ken; >>> Advice from an old electro-mechanical engineer (now 76) and new pilot ( @ >>> 70): Keep the pilot in charge of turning things off. >>> Cheers! Stu. >>> >>> ------------------------------ >>> *From: *"GTH" >>> *To: *aeroelectric-list@matronics.com >>> *Sent: *Friday, October 7, 2016 12:17:19 AM >>> *Subject: *Re: AeroElectric-List: rotax generator without battery >>> >>> >>> *Le 07/10/2016 =C3- 02:09, Ken Ryan a =C3=A9crit : * >>> >>> *I found this Pressure Switch >>> which seems to be a via ble >>> 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 >>> >>> >> > ________________________________ Message 11 ____________________________________ Time: 02:43:27 PM PST US From: Charlie England Subject: Re: AeroElectric-List: rotax generator without battery 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 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 wrote: > >> That's very reasonable; why not just have an on-off switch for the backu p >> 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 alrea dy >> running? >> >> >> >> On Oct 7, 2016, at 15:19, Ken Ryan 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 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 an d >>> switching tanks (Piper, Grumman) or only used for priming and in the ev ent >>> 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 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 ha ve >>> 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 connecte d >>> 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 curren t 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 (an d >>> the switch has been turned on). >>> >>> >>> >>> On Fri, Oct 7, 2016 at 7:30 AM, John Tipton >>> wrote: >>> >>>> Q: how does the engine get it's fuel for start-up, the engine being of f >>>> ie: no oil pressure >>>> >>>> Sent from my iPad >>>> >>>> ----x--O--x---- >>>> >>>> On 7 Oct 2016, at 02:51 pm, ashleysc@broadstripe.net wrote: >>>> >>>> Hi Ken; >>>> Advice from an old electro-mechanical engineer (now 76) and new pilot >>>> (@ 70): Keep the pilot in charge of turning things off. >>>> Cheers! Stu. >>>> >>>> ------------------------------ >>>> *From: *"GTH" >>>> *To: *aeroelectric-list@matronics.com >>>> *Sent: *Friday, October 7, 2016 12:17:19 AM >>>> *Subject: *Re: AeroElectric-List: rotax generator without battery >>>> >>>> >>>> *Le 07/10/2016 =C3- 02:09, Ken Ryan a =C3=A9crit : * >>>> >>>> *I found this Pressure Switch >>>> which seems to be a vi able >>>> 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 >>>> >>>> >>> >> > ________________________________ Message 12 ____________________________________ Time: 03:01:03 PM PST US From: Ken Ryan Subject: Re: AeroElectric-List: 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 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 wire s, > connectors, pressure switch, pressure *line*, etc causing loss of the pum p? > 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 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 engin e >> ceases to turn (because the oil pressure would drop). >> >> Ken >> >> >> On Fri, Oct 7, 2016 at 11:59 AM, Alec Myers 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 lan ding >>> and off the rest of the time. >>> >>> Is there a benefit to having it run full time in parallel with the mai n >>> pump? how do you tell if the main pump has failed if the backup is alre ady >>> running? >>> >>> >>> >>> On Oct 7, 2016, at 15:19, Ken Ryan 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 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 a nd >>>> switching tanks (Piper, Grumman) or only used for priming and in the e vent >>>> 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 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 h ave >>>> 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 i t >>>> 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 r elay >>>> through the Comm-L2 connection. Then, when the engine starts and curre nt is >>>> removed from the starter circuit, power continues to flow the fuel pum p >>>> relay because now with 7lbs of oil pressure Comm is connected to L1 (a nd >>>> the switch has been turned on). >>>> >>>> >>>> >>>> On Fri, Oct 7, 2016 at 7:30 AM, John Tipton >>>> 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@broadstripe.net wrote: >>>>> >>>>> Hi Ken; >>>>> Advice from an old electro-mechanical engineer (now 76) and new pilot >>>>> (@ 70): Keep the pilot in charge of turning things off. >>>>> Cheers! Stu. >>>>> >>>>> ------------------------------ >>>>> *From: *"GTH" >>>>> *To: *aeroelectric-list@matronics.com >>>>> *Sent: *Friday, October 7, 2016 12:17:19 AM >>>>> *Subject: *Re: AeroElectric-List: rotax generator without battery >>>>> >>>>> >>>>> *Le 07/10/2016 =C3- 02:09, Ken Ryan a =C3=A9crit : * >>>>> >>>>> *I found this Pressure Switch >>>>> which seems to be a v iable >>>>> way (combined with a relay) of automatically turning off the auxiliar y fuel >>>>> pump when the engine stops turning.* >>>>> >>>>> >>>>> Your call. You'll make your engine operation dependent on a switch an d >>>>> a relay. >>>>> "On a switch and a prayer" ;-) >>>>> -- >>>>> Best regards, >>>>> Gilles >>>>> http://contrails.free.fr >>>>> http://lapierre.skunkworks.free.fr >>>>> >>>>> >>>> >>> >> > ________________________________ Message 13 ____________________________________ Time: 04:33:00 PM PST US From: Alec Myers Subject: Re: AeroElectric-List: rotax generator without battery Rotax's advice to energize the backup pump for landing is based on limiting t heir own liability rather than improving your overall safety. Even if it's g enuinely 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' ta rmac strips and essentially no risk of inverting the aircraft with adequate p ilot skill rather than rough bush operations. Have you considered overriding their advice and leaving the pump off for lan ding? On Oct 7, 2016, at 17:58, Ken Ryan wrote: Charlie, The primary pump is powered by the integrated generator, so it already has a uto shut off. What are the odds? Well, in off airport operations here in Alaska the odds a re 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 flippe d his airplane, and they all say the same thing: it happened in an instant w ith no warning. Fortunately, they all walked away. Ken > On Fri, Oct 7, 2016 at 1:41 PM, Charlie England wro te: > It really comes down to probability, modified by your personal risk tolera nce. What are the odds of actually needing the auto-off function of the aux p ump (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, pre ssure switch, pressure *line*, etc causing loss of the pump? Or actually *ca using* a problem (pressure line or pressure switch opening an oil exit path c omes to mind...). > > In the 'simple' scenario, the aux pump switch mounted next to the primary p ump 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 wrote: >> Alec, >> >> I'm not sure where you got the idea that the auxiliary pump would be runn ing all the time. It would indeed be used only for takeoffs and landings, vi a a toggle switch. But inserting the pressure switch and the relay would ins ure that in the event of a crash, such as on takeoff or landing, the auxilia ry pump would automatically shut down when the engine ceases to turn (becaus e the oil pressure would drop). >> >> Ken >> >> >>> On Fri, Oct 7, 2016 at 11:59 AM, Alec Myers wrote: >>> That's very reasonable; why not just have an on-off switch for the backu p pump? Switch it on on the ground to test, on for takeoff and landing and o ff 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 r unning? >>> >>> >>> >>> On Oct 7, 2016, at 15:19, Ken Ryan wrote: >>> >>> Rotax operating procedures for 914 call for running both electric fuel p umps for takeoff and landings. >>> >>>> On Fri, Oct 7, 2016 at 10:59 AM, Alec Myers 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 e lectric backup pump but it's either on only for takeoff and landing and swit ching tanks (Piper, Grumman) or only used for priming and in the event of en gine storage due to main pump failure (Cessna) >>>> >>>> I'm not familiar with the proposed system so If the backup pump is perm anently energised what alerts the pilot to a failure of the engine-driven pu mp? >>>> >>>> >>>>> On Oct 7, 2016, at 12:27 PM, Ken Ryan wrote: >>>>> >>>>> I think maybe some of you are not factoring in that this is on the aux iliary fuel pump only. So for a failure of the switch or relay to have any e ffect on the flight, the main fuel pump would have already had to fail. The p rimary fuel pump stops automatically when the engine stops turning because i t is powered off the generator. >>>>> >>>>> As far as startup, I think the way the pressure switch works is that i t is a single pole, double throw. So there are three terminals: Comm, L1, an d L2. Without pressure, Comm is connected to L2. With pressure, Comm is conn ected 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 connect ed Comm-L2 only, closing the fuel pump switch would do nothing. But when cra nking power is put to the starter, current would flow to the relay through t he Comm-L2 connection. Then, when the engine starts and current is removed f rom 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 b een turned on). >>>>> >>>>> >>>>> >>>>>> On Fri, Oct 7, 2016 at 7:30 AM, John Tipton wrote: >>>>>> Q: how does the engine get it's fuel for start-up, the engine being o ff ie: no oil pressure >>>>>> >>>>>> Sent from my iPad >>>>>> >>>>>> ----x--O--x---- >>>>>> >>>>>>> On 7 Oct 2016, at 02:51 pm, ashleysc@broadstripe.net wrote: >>>>>>> >>>>>>> Hi Ken; >>>>>>> Advice from an old electro-mechanical engineer (now 76) and new pilo t (@ 70): Keep the pilot in charge of turning things off. >>>>>>> Cheers! Stu. >>>>>>> >>>>>>> From: "GTH" >>>>>>> To: aeroelectric-list@matronics.com >>>>>>> Sent: Friday, October 7, 2016 12:17:19 AM >>>>>>> Subject: Re: AeroElectric-List: rotax generator without battery >>>>>>> >>>>>>> Le 07/10/2016 =C3- 02:09, Ken Ryan a =C3=A9crit : >>>>>>> I found this Pressure Switch which seems to be a viable way (combine d with a relay) of automatically turning off the auxiliary fuel pump when th e engine stops turning. >>>>>>> >>>>>>> Your call. You'll make your engine operation dependent on a switch a nd a relay. >>>>>>> "On a switch and a prayer" ;-) >>>>>>> -- >>>>>>> Best regards, >>>>>>> Gilles >>>>>>> http://contrails.free.fr >>>>>>> http://lapierre.skunkworks.free.fr >>>>>>> >>>>> >>> >> > ________________________________ Message 14 ____________________________________ Time: 05:15:59 PM PST US From: Ken Ryan Subject: Re: AeroElectric-List: rotax generator without battery Alec, Yes I have indeed considered that! On Fri, Oct 7, 2016 at 3:30 PM, Alec Myers wrote: > 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 wrote: > > Charlie, > > The primary pump is powered by the integrated generator, so it already ha s > auto shut off. > > What are the odds? Well, in off airport operations here in Alaska the odd s > 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 ha s > 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 > wrote: > >> It really comes down to probability, modified by your personal risk >> tolerance. What are the odds of actually needing the auto-off function o f >> 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 needin g >> the backup pump (primary failure) and risking any one of the various wir es, >> connectors, pressure switch, pressure *line*, etc causing loss of the pu mp? >> Or actually *causing* a problem (pressure line or pressure switch openin g >> an oil exit path comes to mind...). >> >> In the 'simple' scenario, the aux pump switch mounted next to the primar y >> 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 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 th e >>> 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 engi ne >>> ceases to turn (because the oil pressure would drop). >>> >>> Ken >>> >>> >>> On Fri, Oct 7, 2016 at 11:59 AM, Alec Myers 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 la nding >>>> 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 i s >>>> already running? >>>> >>>> >>>> >>>> On Oct 7, 2016, at 15:19, Ken Ryan 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 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 a n >>>>> 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 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 t o >>>>> 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, Com m 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 curr ent is >>>>> removed from the starter circuit, power continues to flow the fuel pu mp >>>>> 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 >>>>> 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@broadstripe.net wrote: >>>>>> >>>>>> Hi Ken; >>>>>> Advice from an old electro-mechanical engineer (now 76) and new pilo t >>>>>> (@ 70): Keep the pilot in charge of turning things off. >>>>>> Cheers! Stu. >>>>>> >>>>>> ------------------------------ >>>>>> *From: *"GTH" >>>>>> *To: *aeroelectric-list@matronics.com >>>>>> *Sent: *Friday, October 7, 2016 12:17:19 AM >>>>>> *Subject: *Re: AeroElectric-List: rotax generator without battery >>>>>> >>>>>> >>>>>> *Le 07/10/2016 =C3- 02:09, Ken Ryan a =C3=A9crit : * >>>>>> >>>>>> *I found this Pressure Switch >>>>>> which seems to be a viable >>>>>> way (combined with a relay) of automatically turning off the auxilia ry 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 >>>>>> >>>>>> >>>>> >>>> >>> >> > ________________________________ Message 15 ____________________________________ Time: 05:33:00 PM PST US Subject: Re: AeroElectric-List: rotax generator without battery From: rayj 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 > 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 > 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 > 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 > 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 > > 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 > > > 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 >> > > 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@broadstripe.net >> wrote: >> >>> Hi Ken; >>> Advice from an old electro-mechanical engineer >>> (now 76) and new pilot (@ 70): Keep the pilot in >>> charge of turning things off. >>> Cheers! Stu. >>> >>> ------------------------------------------------------------------------ >>> *From: *"GTH" >> > >>> *To: *aeroelectric-list@matronics.com >>> >>> *Sent: *Friday, October 7, 2016 12:17:19 AM >>> *Subject: *Re: AeroElectric-List: rotax generator >>> without battery >>> >>> /Le 07/10/2016 02:09, Ken Ryan a crit : >>> / >>> >>> /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 >>> >>> >> > > ________________________________ Message 16 ____________________________________ Time: 08:17:35 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: rotax generator without battery At 02:17 AM 10/7/2016, you wrote: >Le 07/10/2016 =C3 02:09, Ken Ryan a =C3=A9crit=C2 : >>I found this=C2 >>Pressure >>Switch=C2 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 . . . ________________________________ Message 17 ____________________________________ Time: 10:53:11 PM PST US From: Ken Ryan Subject: Re: AeroElectric-List: 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 wrote: > > 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; Challengi ng > 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 reliab le > 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 awa y. >> >> Ken >> >> On Fri, Oct 7, 2016 at 1:41 PM, Charlie England > > 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 > > 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 > > 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 > > 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 >> > 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 >> > >> 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 >>> >> > 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@broadstripe.net >>> wrote: >>> >>> Hi Ken; >>>> Advice from an old electro-mechanical engineer >>>> (now 76) and new pilot (@ 70): Keep the pilot in >>>> charge of turning things off. >>>> Cheers! Stu. >>>> >>>> ------------------------------ >>>> ------------------------------------------ >>>> *From: *"GTH" >>> > >>>> *To: *aeroelectric-list@matronics.com >>>> >>>> *Sent: *Friday, October 7, 2016 12:17:19 AM >>>> *Subject: *Re: AeroElectric-List: rotax generator >>>> without battery >>>> >>>> /Le 07/10/2016 =C3- 02:09, Ken Ryan a =C3=A9crit : >>>> / >>>> >>>> /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 >>>> >>>> >>>> >>> >> >> >> >> =========== =========== =========== =========== =========== > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.