---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 10/22/16: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:54 AM - Re: Coiled ignition systems (user9253) 2. 11:03 AM - Re: Re: Coiled ignition systems (Robert L. Nuckolls, III) 3. 12:39 PM - Re: Re: Coiled ignition systems (C&K) 4. 01:54 PM - Re: Re: Coiled ignition systems (Charlie England) 5. 07:07 PM - Hourmeter / oil pressure switch (micreb) ________________________________ Message 1 _____________________________________ Time: 06:54:26 AM PST US Subject: AeroElectric-List: Re: Coiled ignition systems From: "user9253" If a forced landing is immanent, all electrical power should be shut off to prevent ignition of leaking fuel. A master switch that shuts off everything including the engine is good for that scenario. However, smoke in the cockpit is an emergency that may require shutting off all electrical loads except the engine. In that case, engine ignition needs to be independent of the master switch. The most reliable ignition circuit is less complicated and has fewer components. If it were my plane, I would power the ignition system from the battery, independent of the master switch. The engine starter circuit should be disabled when the master switch is off. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=461520#461520 ________________________________ Message 2 _____________________________________ Time: 11:03:42 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Coiled ignition systems At 08:53 AM 10/22/2016, you wrote: > >If a forced landing is immanent, all electrical power should be shut >off to prevent ignition of leaking fuel. A master switch that shuts >off everything including the engine is good for that >scenario. However, smoke in the cockpit is an emergency that may >require shutting off all electrical loads except the engine. In >that case, engine ignition needs to be independent of the master >switch. The most reliable ignition circuit is less complicated and >has fewer components. If it were my plane, I would power the >ignition system from the battery, independent of the master >switch. The engine starter circuit should be disabled when the >master switch is off. Agreed . . . Since your ignition system will run nicely on 7A or less, I too would recommend you run the ignition directly from the battery through a 7A fuse. Power the starter from the bus powered through the master contactor. The ignition circuit is low risk for post-crash ignition source . . . so even if you don't get the engine killed before anticipated contact the primary risk is to the engine having a powered prop strike. Taking everything else through the battery master is the conventional philosophy. Bob . . . ________________________________ Message 3 _____________________________________ Time: 12:39:20 PM PST US Subject: Re: AeroElectric-List: Re: Coiled ignition systems From: C&K A 7 amp CB seems reasonable but a 7 amp fuse makes me a bit nervous. I seem to recall that when I looked at ignition currents I noted that they went up at high rpm, at high temperatures, and in some rare cases when the engine was not turning. I did not notice any automotive systems that lightly fused the ignition circuits. So while I've never measured over 5 amps on my soob units, my personal recommendation is a minimum 10 amp fuse on ignition circuits that feed multiple cylinders even if they are solid state. It may be that the peak currents as seen on a scope caught my attention or that I just like more headroom on critical fuses. I think part of my thought process might have been that on my system if one solid state coil driver shorted full on it would not necessarily take out the system fuse. I don't have any idea what the tolerance is on an ATC fuse. I have 700 hours on the original 10 amp fuses that feed the 4 cylinder soob. I've had two cases of one cylinder losing power due to a partial coil failure. Once during initial ground testing and once at around 500 hours. These are DIS coils that each feed two cylinders but in both cases only one cylinder lost power. Ken On 22/10/2016 2:02 PM, Robert L. Nuckolls, III wrote: > At 08:53 AM 10/22/2016, you wrote: >> >> If a forced landing is immanent, all electrical power should be shut >> off to prevent ignition of leaking fuel. A master switch that shuts >> off everything including the engine is good for that scenario. >> However, smoke in the cockpit is an emergency that may require >> shutting off all electrical loads except the engine. In that case, >> engine ignition needs to be independent of the master switch. The >> most reliable ignition circuit is less complicated and has fewer >> components. If it were my plane, I would power the ignition system >> from the battery, independent of the master switch. The engine >> starter circuit should be disabled when the master switch is off. > > Agreed . . . > > Since your ignition system will run nicely > on 7A or less, I too would recommend you > run the ignition directly from the battery > through a 7A fuse. Power the starter from > the bus powered through the master contactor. > > The ignition circuit is low risk for post-crash > ignition source . . . so even if you don't > get the engine killed before anticipated > contact the primary risk is to the engine > having a powered prop strike. > > Taking everything else through the battery > master is the conventional philosophy. > > > Bob . . . > ________________________________ Message 4 _____________________________________ Time: 01:54:05 PM PST US Subject: Re: AeroElectric-List: Re: Coiled ignition systems From: Charlie England Ken brings up an easy redundancy opportunity. Some (most?) automotive style engine controllers switch the ground side of the coils and the injectors. To limit the impact of such failures, I chose to independently fuse each coil. Might be worth a look if running an auto style engine controller. Charlie On 10/22/2016 2:37 PM, C&K wrote: > > A 7 amp CB seems reasonable but a 7 amp fuse makes me a bit nervous. I > seem to recall that when I looked at ignition currents I noted that > they went up at high rpm, at high temperatures, and in some rare cases > when the engine was not turning. I did not notice any automotive > systems that lightly fused the ignition circuits. So while I've never > measured over 5 amps on my soob units, my personal recommendation is a > minimum 10 amp fuse on ignition circuits that feed multiple cylinders > even if they are solid state. It may be that the peak currents as > seen on a scope caught my attention or that I just like more headroom > on critical fuses. I think part of my thought process might have been > that on my system if one solid state coil driver shorted full on it > would not necessarily take out the system fuse. I don't have any idea > what the tolerance is on an ATC fuse. I have 700 hours on the original > 10 amp fuses that feed the 4 cylinder soob. I've had two cases of one > cylinder losing power due to a partial coil failure. Once during > initial ground testing and once at around 500 hours. These are DIS > coils that each feed two cylinders but in both cases only one cylinder > lost power. > Ken > > On 22/10/2016 2:02 PM, Robert L. Nuckolls, III wrote: >> At 08:53 AM 10/22/2016, you wrote: >>> >>> If a forced landing is immanent, all electrical power should be shut >>> off to prevent ignition of leaking fuel. A master switch that shuts >>> off everything including the engine is good for that scenario. >>> However, smoke in the cockpit is an emergency that may require >>> shutting off all electrical loads except the engine. In that case, >>> engine ignition needs to be independent of the master switch. The >>> most reliable ignition circuit is less complicated and has fewer >>> components. If it were my plane, I would power the ignition system >>> from the battery, independent of the master switch. The engine >>> starter circuit should be disabled when the master switch is off. >> >> Agreed . . . >> >> Since your ignition system will run nicely >> on 7A or less, I too would recommend you >> run the ignition directly from the battery >> through a 7A fuse. Power the starter from >> the bus powered through the master contactor. >> >> The ignition circuit is low risk for post-crash >> ignition source . . . so even if you don't >> get the engine killed before anticipated >> contact the primary risk is to the engine >> having a powered prop strike. >> >> Taking everything else through the battery >> master is the conventional philosophy. >> >> >> >> >> Bob . . . >> > ________________________________ Message 5 _____________________________________ Time: 07:07:04 PM PST US Subject: AeroElectric-List: Hourmeter / oil pressure switch From: "micreb" Hope someone might be able to help out here. I have a three pin oil pressure switch that feeds my low oil pressure light and turns on the Hobbs meter. The reference I have is a wiring diagram from Aeroelectric somewhere along the line but no figure or diagram number. The only reference is on the part, D-86117. I can't seem to cross it to anything useful to replace it. Would someone have a good number to order a replacement? Paul -------- I'd rather be flying than building but there's an end to the means here (I hope). 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