---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 10/26/13: 35 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:52 AM - Re: EXP 2 Bus workaround (Ken) 2. 05:51 AM - Re: Landing gear warning trigger (donjohnston) 3. 06:05 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 4. 06:50 AM - Re: Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 5. 06:52 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 6. 06:58 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 7. 06:59 AM - Re: EXP 2 Bus workaround (John W Livingston) 8. 07:45 AM - Re: EXP 2 Bus workaround (Fred Klein) 9. 07:58 AM - Re: EXP 2 Bus workaround (Richard Girard) 10. 08:42 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 11. 08:46 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 12. 08:49 AM - Re: EXP 2 Bus workaround (Ken) 13. 08:54 AM - Re: EXP 2 Bus workaround (Fred Klein) 14. 08:58 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 15. 09:08 AM - Re: EXP 2 Bus workaround (Fred Klein) 16. 09:59 AM - Re: EXP 2 Bus workaround (Fred Klein) 17. 10:10 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 18. 10:30 AM - Re: EXP 2 Bus workaround (Fred Klein) 19. 10:57 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 20. 11:22 AM - Re: EXP 2 Bus workaround (Fred Klein) 21. 11:37 AM - Re: EXP 2 Bus workaround (Bob McCallum) 22. 12:26 PM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 23. 12:38 PM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 24. 12:51 PM - Re: EXP 2 Bus workaround (user9253) 25. 12:54 PM - Re: Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 26. 01:21 PM - Re: EXP 2 Bus workaround (Bob McCallum) 27. 01:56 PM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 28. 02:10 PM - Re: EXP 2 Bus workaround (Fred Klein) 29. 02:16 PM - Re: EXP 2 Bus workaround (Fred Klein) 30. 02:20 PM - Re: EXP 2 Bus workaround (user9253) 31. 06:50 PM - EXP 2 Bus workaround - Master Solenoid Failure (Jeff Luckey) 32. 08:16 PM - Re: EXP 2 Bus workaround - Master Solenoid Failure (Robert L. Nuckolls, III) 33. 08:25 PM - Re: EXP 2 Bus workaround - Master Solenoid Failure (Robert L. Nuckolls, III) 34. 10:01 PM - Re: EXP 2 Bus workaround - Master Solenoid Failure (Jeff Luckey) 35. 10:33 PM - Battery contactor failure (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 03:52:14 AM PST US From: Ken Subject: Re: AeroElectric-List: EXP 2 Bus workaround FWIW two parallel subaru oem EFI pumps from a 4 cylinder legacy work fine with a oem regulator all of 1990 to 1994 vintage. Pressure goes up no more than 2 psi. even with my somewhat restrictive 5/16" return plumbing. Some fellows run both pumps for landing and takeoff. Selecting both on is the first thing we do if the engine is not running properly. Injector flow increases with the square root of pressure so that is not an issue since normal EFI pressures run around 38 psi above manifold pressure. Ken On 25/10/2013 10:42 PM, Robert L. Nuckolls, III wrote: > * > * >> Let's talk about the 2 fuel pumps for a MPEFI engine. Unlike w/ carb >> engines, the 2nd pump is not used as a boost pump. I'm advised that w/ >> a MPEFI engine, one never wants to run more than ONE pump at a time >> due to excessive pressure in the system. > > * How does this happen? I understand that there's a pressure > regulator downstream of the pump outputs. Paralleling two > active pumps only increases potential for flow . . . like > hooking two batteries in parallel.* ________________________________ Message 2 _____________________________________ Time: 05:51:07 AM PST US Subject: AeroElectric-List: Re: Landing gear warning trigger From: "donjohnston" > Yep. You already have a fabricated bracket and two anchor bolts available > close by. I'd just re-make the existing bracket (or add a new one) to > extend toward the lever arm and mount a micro switch. You could put an 'L' > shaped tab on the arm using the existing hole to contact the switch if you > need to move the assembly inboard to clear the fuel line. Nope. That's what is typically done. But the routing of my MAP line doesn't allow for that. I couldn't get a picture showing it, but extending the bracket would require new fittings and a new MAP line to be fabricated. I'm trying to see if there's a workaround. > Or like I mentioned before, mount the switch remotely and activate it with a slave rod (piano wire) from the lever arm...on either side (push or pull can work). That's a little more complicated but allows you to work around space limitations or obstructions if needed. That's a thought. I'll have to look and see how much trouble that's going to be. > Simple stuff...bunches of various options. I see no real need for something complex. Agreed. That's why I was thinking of a MAP switch that would close when the MAP got down to around 12-13" > BTW, I hope this you have already addressed this - that mounting clamp looks not to be fully secured. You dont want to "pre-disaster" yourself and have the throttle linkage come loose in flight. Just checking. I'm a LONG way off from even starting the engine. Let alone moving under it's own power. When things are tightened/secured, they get some torque seal. Until then, it's easier to remove for other installations and modifications. Thanks, Don Read this topic online here: http://forums.matronics.com/viewtopic.php?p=411442#411442 ________________________________ Message 3 _____________________________________ Time: 06:05:26 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround At 11:44 PM 10/25/2013, you wrote: >I am still stumped as to why you would recommend one battery. I >could agree if the one alternator is guaranteed to work without the >battery in the circuit, but not without that backup. You must think >batteries are much more reliable than I do. Oky, let's ex[;pre that premise. What in your studies and/or experience with batteries leads you to believe that they demonstrate a risky, in-service failure rate? Before you add a second battery, are there things that can be done to mitigate your concerns and reduce in-service failures to acceptable risk levels? Recall that the original premise for dual batteries had nothing to do with worries for battery failure and everything to do with walling off known quantities of energy off to do separate tasks . . . where one of those tasks was critical to continued flight: keep the engine running. The two battery concept was never intended to be a hedge against the failure of one battery. Bob . . . ________________________________ Message 4 _____________________________________ Time: 06:50:22 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: EXP 2 Bus workaround At 01:51 AM 10/26/2013, you wrote: On Oct 25, 2013, at 6:32 AM, Robert L. Nuckolls, III wrote: Attached are the preliminary sketches for my current thoughts on an architecture for single battery, single alternator, electrically dependent engine. This line of thinking is being developed as an preferred alternative to Z-19. Bob...I'm delighted that my queries have triggered your taking a fresh look at Z-19...and presumably, Z-19RB. This architecture has roots in Z-11 Three-Bus structure with the addition of a Motive Power Bus (engine). With the term E-bus already in legacy use, the MP-Bus terminology offers a stand-out label that avoids confusion. ...perhaps it won't be too long before MP busses will morph into ones intended for truly all electric power trains... The major difference is the addition of the MP-bus having normal feedpath from the main bus, alternate feedpath from the battery . . . same as the E-Bus except BOTH pathways have panel mounted switches. The e-bus is always hot any time the main bus is hot, but the MP-Bus as power to the engine needs to be controlled through both pathways. I'm thinking that the EXP-bus can be folded into this architecture by conversion of battery switch to DC master and take alternator field through second pole. Convert the 'avionice master' Engine A. Use switch between the big red rockers as e-bus alternate feed. Switch to right of Engine A is Engine B. From the get-go, my intent has been to supplement the capabilities of the EXP Bus to provide for the special requirements for a MPEFI engine AND to provide the alternate feeds featured in AeroElectric's Z-xx diagrams in case something goes amiss. I question your suggestion to: Use switch between the big red rockers as e-bus alternate feed. Switch to right of Engine A is Engine B. I'm reluctant to interpose within the row of EXP Bus rockers, switches which would only be used during an emergency. Conceptually, I much prefer the notion of having a row of rockers, all of which are used in the course of normal operations...and a second, distinctly different row of rockers which will only be used during emergencies. Please . . . purge the work EMERGENCY from your thought processes. Things on airplanes break all the time. If they did not, FBO maintenance shops would be out of business and Jiffy-Lube could move into the empty space while adding a wash-rack. You have Plan-A, everything works in accordance with the refined constellation of design goals. Then there is Plan-B, something broke . . . a condition that has been anticipated in our FEMA and we're dealing with it under a sub-set of the original design goals. Then there's Plan-C, supported by some goodies in the flight bag that describe yet a smaller sub-set of original design goals. An airplane configured artfully conducted FMEA operating by a pilot who understands the machine's strengths and weaknesses does not experience electrical emergencies . . . only events of in-service failure or wear-out that will need to be hammered on once you've arrived at your intended destination. (The wide, red, Master switch at the left end...distinctive in both width and color...is of course used both in normal and emergency ops.) Organizing the panel in this manner...at least to me...sets the stage for calm and cool actions when under stress. I understand your desire for me to proceed w/ listing of elec loads for all components...a task I recognise as essential...but first I want to be confident that I understand the big picture. And the big picture for me is how we supplement the capabilities of the EXP Bus in order to have the benefits of engine and endurance busses with alternate feeds from the battery. The BIG picture is that drawing I published. You're getting distracted by the existence of the EXP-Bus. Notwithstanding the shortcomings, some poor choices, and undoubtedly some serious errors, the last diagram I posted (Revision #XX) did two things of note: First, it pulls power from the EXP Master Bus for the MP (engine) bus from 2 - 11 amp circuits, AUX1 and AUX2. (...now I don't know exactly how those 2 circuits can be combined, but something tells me there's a way which is simple and direct...) Second, the Revision XX diagram shows the EXP Avionics Bus powering the E-bus (endurance) from a 7 amp circuit. (...btw, I don't understand the notion that we should be rid of the avionics master switch...). Also...note that w/ Skyview and the back up GPS both having their own back up batteries, if either the Master switch or the Avionics Master is turned off and the E-bus Alternate Feed is energized, we'll be back in business w/ a full suite of avionics. The avionics master switch was a flawed idea from the get-go. I was at Cessna when the thing was birthed and I've come to understand how we marched off down that no-value-added path. See: http://tinyurl.com/pgcgx9m It strikes me that this approach is elegant, simple, and direct; I shudder at the thought of altering any part of the circuitry within the EXP Bus other than changing some Fast-on spades of a couple of switches and relabeling them. Ignore the EXP=Bus for now, we need to make the architecture work first. I'm baffled when you write, "Old avionics bus becomes e-bus." There is presently an avionics master switch that controls all power to a chunk of copper glued to the epoxy-glas that distributes power to terminals on the board through an array of poly-fuses. This is your 'avionics' bus which I believe can become your new e-bus. ...as I look at the circuit board of the EXP Bus, I haven't a clue how this can happen and create the alternate feed intrinsic w/ the e-bus concept...way outside my comfort zone to poke around in that circuit board. It's just "wires" glued to a piece of epoxy-glas. Nothing happens on that assembly that a large number of our contemporaries haven't done with fuses, wires, breakers and switches. The marketing-hook for an EXP-Bus is it's relative complexity for stuffing a lot of activity into a small volume and then offering it to the customer as, "Here, look at all these things we did FOR you so that you don't HAVE to." The question never asked and answered is, "Does that assembly DO things that people who choose not to use your product will wish they had included at some later time?" In other words, what is the return on investment for you having exchanged your dollars for their time, talents and resources? That's what we're doing here right now. The sketches I published don't speak to how the EXP-Bus will be 'jeeped' (Old television vernacular for modifying a piece of equipment to some new task not offered by the designers) into the spirit and intent of the new Z-figure. Let's assume for the moment that EXP-Bus is not present. The sketches are not a "Z-figure for EXP-Buses" . . . it's a new architecture is a stand alone recipe for success crafted from rudimentary ingredients. Making a practical adaptation of an EXP-Bus to the task is a separate activity we can tackle after the cake is in the oven. It's just 'frosting' . . . Bob . . . ________________________________ Message 5 _____________________________________ Time: 06:52:55 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround At 05:51 AM 10/26/2013, you wrote: > >FWIW two parallel subaru oem EFI pumps from a 4 cylinder legacy work >fine with a oem regulator all of 1990 to 1994 vintage. Pressure goes >up no more than 2 psi. even with my somewhat restrictive 5/16" >return plumbing. Some fellows run both pumps for landing and >takeoff. Selecting both on is the first thing we do if the engine is >not running properly. Injector flow increases with the square root >of pressure so that is not an issue since normal EFI pressures run >around 38 psi above manifold pressure. Good data sir. Thanks! Bob . . . ________________________________ Message 6 _____________________________________ Time: 06:58:14 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround >> Is anyone flying this combination of hardware? How much does >> IAS need to be reduced to stop a windmilling prop? The few >> times I stopped the prop on a TC airplane I had to really >> work at it. The idea that one needs access to a starter >> motor in flight is mostly without foundation. This is a >> fact you need to resolve for your harware combination. > >Bob...I'm getting some data on this. Does your engine feature a PSRU? If so, does it include a spag-clutch on the propeller shaft for mitigation of rotational vibration stresses on the gearbox? If so, then the prop windmills at all speeds and does not back-drive the engine. But in any case, pushing a starter button with the notion that a starter will respond assumer is ales a battery contactor is closed and FAT-wire power is also available to the starter. Starter button is not an E-bus load. Bob . . . ________________________________ Message 7 _____________________________________ Time: 06:59:05 AM PST US From: John W Livingston Subject: Re: AeroElectric-List: EXP 2 Bus workaround On this list we have seen examples of internal battery failures and wire connector failures and switch failures. Granted that these things typically have low failure rates, but if they happen, you have no backup. By going with one battery and not knowing if the alternator will back you up you have elevated these failures to the status of a prop, engine, wing or control surface failure. John On 10/26/2013 9:03 AM, Robert L. Nuckolls, III wrote: > At 11:44 PM 10/25/2013, you wrote: >> I am still stumped as to why you would recommend one battery. I could >> agree if the one alternator is guaranteed to work without the battery >> in the circuit, but not without that backup. You must think batteries >> are much more reliable than I do. > > Oky, let's ex[;pre that premise. What in your > studies and/or experience with batteries leads > you to believe that they demonstrate a risky, > in-service failure rate? > Before you add a second battery, are there things > that can be done to mitigate your concerns and > reduce in-service failures to acceptable risk > levels? > > Recall that the original premise for dual batteries > had nothing to do with worries for battery failure > and everything to do with walling off known quantities > of energy off to do separate tasks . . . where one > of those tasks was critical to continued flight: > keep the engine running. The two battery concept was > never intended to be a hedge against the failure > of one battery. > > Bob . . . > > * > > > * ________________________________ Message 8 _____________________________________ Time: 07:45:27 AM PST US From: Fred Klein Subject: Re: AeroElectric-List: EXP 2 Bus workaround On Oct 26, 2013, at 3:51 AM, Ken wrote: > FWIW two parallel subaru oem EFI pumps from a 4 cylinder legacy work fine with a oem regulator all of 1990 to 1994 vintage. Pressure goes up no more than 2 psi. even with my somewhat restrictive 5/16" return plumbing. Some fellows run both pumps for landing and takeoff. Selecting both on is the first thing we do if the engine is not running properly. Injector flow increases with the square root of pressure so that is not an issue since normal EFI pressures run around 38 psi above manifold pressure. Thanks Ken...I stand corrected...my engine at 1.8 L is a tad smaller than your Legacy...it's set up w/ 3/8" fuel supply line and a 1/4" return line using R9 injector hose aft of my firewall. I believe the fuel pressure regulator has been set to factor in whatever restrictive backpressure the 1/4" return line contributes. Ron Carr at RAM Performance sez my engine's fuel pressure will be 38 psi at idle and rise to 43 psi at WOT. (I have not discussed the dual pump issues w/ him because he sells his engines with only one pump.) Fred ________________________________ Message 9 _____________________________________ Time: 07:58:13 AM PST US Subject: Re: AeroElectric-List: EXP 2 Bus workaround From: Richard Girard Fred, Bob, et al, I have no dog in this fight, I've just been following the discussion but I've got to ask; with all these workarounds you're doing to make the EXPBus work with your airplane's systems, what is it buying you? The Spruce description of the EXPBus is all about easy squeazy installation and time savings, yet you're being forced into more and more redesign and adaptation in order to make it work for you. I realize that you're a long way down the road with this thing but have you thought about just grabbing a clean sheet of paper and sending the EXPBus to eBay? Rick Girard On Sat, Oct 26, 2013 at 8:58 AM, John W Livingston wrote: > On this list we have seen examples of internal battery failures and wire > connector failures and switch failures. Granted that these things typically > have low failure rates, but if they happen, you have no backup. By going > with one battery and not knowing if the alternator will back you up you > have elevated these failures to the status of a prop, engine, wing or > control surface failure. > > John > > > On 10/26/2013 9:03 AM, Robert L. Nuckolls, III wrote: > > At 11:44 PM 10/25/2013, you wrote: > > I am still stumped as to why you would recommend one battery. I could > agree if the one alternator is guaranteed to work without the battery in > the circuit, but not without that backup. You must think batteries are much > more reliable than I do. > > > Oky, let's ex[;pre that premise. What in your > studies and/or experience with batteries leads > you to believe that they demonstrate a risky, > in-service failure rate? > > > Before you add a second battery, are there things > that can be done to mitigate your concerns and > reduce in-service failures to acceptable risk > levels? > > Recall that the original premise for dual batteries > had nothing to do with worries for battery failure > and everything to do with walling off known quantities > of energy off to do separate tasks . . . where one > of those tasks was critical to continued flight: > keep the engine running. The two battery concept was > never intended to be a hedge against the failure > of one battery. > > ** > > Bob . . . > > * > > * > > ** > > > * > > * > > -- Zulu Delta Mk IIIC Thanks, Homer GBYM It isn't necessary to have relatives in Kansas City in order to be unhappy. - Groucho Marx ________________________________ Message 10 ____________________________________ Time: 08:42:45 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround At 09:57 AM 10/26/2013, you wrote: >Fred, Bob, et al, I have no dog in this fight, I've just been >following the discussion but I've got to ask; with all these >workarounds you're doing to make the EXPBus work with your >airplane's systems, what is it buying you? The Spruce description of >the EXPBus is all about easy squeazy installation and time savings, >yet you're being forced into more and more redesign and adaptation >in order to make it work for you. I realize that you're a long way >down the road with this thing but have you thought about just >grabbing a clean sheet of paper and sending the EXPBus to eBay? For me, this discussion is NOT an attempt to craft a Z-Figures for EXP-Bus. It's a new look at Z-19 and other manifestations of two-battery installations to explore well reasoned alternatives. When and if the new Z-figure makes it to the back of the book, then well see if we can fiddle with an EXP-Bus to achieve the same architecture crafted to design goals. Bob . . . ________________________________ Message 11 ____________________________________ Time: 08:46:00 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround At 09:44 AM 10/26/2013, you wrote: >On Oct 26, 2013, at 3:51 AM, Ken wrote: > >>FWIW two parallel subaru oem EFI pumps from a 4 cylinder legacy >>work fine with a oem regulator all of 1990 to 1994 vintage. >>Pressure goes up no more than 2 psi. even with my somewhat >>restrictive 5/16" return plumbing. Some fellows run both pumps for >>landing and takeoff. Selecting both on is the first thing we do if >>the engine is not running properly. Injector flow increases with >>the square root of pressure so that is not an issue since normal >>EFI pressures run around 38 psi above manifold pressure. > >Thanks Ken...I stand corrected...my engine at 1.8 L is a tad smaller >than your Legacy...it's set up w/ 3/8" fuel supply line and a 1/4" >return line using R9 injector hose aft of my firewall. I believe the >fuel pressure regulator has been set to factor in whatever >restrictive backpressure the 1/4" return line contributes. > >Ron Carr at RAM Performance sez my engine's fuel pressure will be 38 >psi at idle and rise to 43 psi at WOT. The question to be answered for evolving this new architecture is whether or not having two pumps on at the same time represents any kind of hazard. The second pump is included to mitigate the failure of the first pump. The first pump is presently powered any time the MP-Bus is hot. If the pump works, then the second pump is not needed. If the first pump fails, the second pump is available. At no time has anyone suggested that the pumps should be operated simultaneously on purpose. Bob . . . ________________________________ Message 12 ____________________________________ Time: 08:49:52 AM PST US From: Ken Subject: Re: AeroElectric-List: EXP 2 Bus workaround > Is anyone flying this combination of hardware? How much does > IAS need to be reduced to stop a windmilling prop? The few > times I stopped the prop on a TC airplane I had to really > work at it. The idea that one needs access to a starter > motor in flight is mostly without foundation. This is a > fact you need to resolve for your harware combination. Somewhat different hardware but indicative. With a 1.92 gear ratio and a 3 bladed 72" non-tapered warp prop my ej22 windmills down to below 40 knots. However if I do intentionally stop it (difficult to do with a best glide speed of about 65 knots), a 120 knot dive is insufficient to get a restart. More interesting was that unlike many airplanes, my Rebel has about the same glide ratio whether windmilling or stopped which surprised me. Obviously I do not have one of the sprag clutch type arrangements that have been so troublesome... Ken ________________________________ Message 13 ____________________________________ Time: 08:54:35 AM PST US From: Fred Klein Subject: Re: AeroElectric-List: EXP 2 Bus workaround On Oct 26, 2013, at 7:57 AM, Richard Girard wrote: > Fred, Bob, et al, I have no dog in this fight, I've just been following the discussion but I've got to ask; with all these workarounds you're doing to make the EXPBus work with your airplane's systems, what is it buying you? The Spruce description of the EXPBus is all about easy squeazy installation and time savings, yet you're being forced into more and more redesign and adaptation in order to make it work for you. I realize that you're a long way down the road with this thing but have you thought about just grabbing a clean sheet of paper and sending the EXPBus to eBay? Good question Rick...and one I've asked myself many times. My answer has been that I'll chuck the EXP Bus when I reach the conclusion that doing so will solve more problems than it creates. I'm still a long way from that. Your first question..."what is it buying you?"...is an even better question, and I regret that I was simply too ignorant to read between the lines of the marketing hype...I confess to have been dazzled by the EXP's obvious complexity (to what end?) and my belief that "I guess I need to buy one of these, cause I sure wouldn't want to trust myself to build one". As I presently understand things, the EXP can serve as my main power distribution bus and provides circuits which can be used to power an engine bus (or Motive Power Bus, to use Bob's new term) and an endurance bus, both of which want to have alternate power feeds direct from the battery. All this seems fine and doable without making circuitry changes within the EXP, something I'm loath to do, primarily because of my inexperience and unfamiliarity w/ things electronic. I can only commend Bob for his patience with me, Fred ________________________________ Message 14 ____________________________________ Time: 08:58:18 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround At 08:58 AM 10/26/2013, you wrote: >On this list we have seen examples of internal battery failures and >wire connector failures and switch failures. Granted that these >things typically have low failure rates, but if they happen, you >have no backup. By going with one battery and not knowing if the >alternator will back you up you have elevated these failures to the >status of a prop, engine, wing or control surface failure. Let's concentrate on battery failures . . . and the failure of components that hook that battery to ground and the contactor stud. What was the nature of failures internal to the battery? What was the nature of failure for any wires/connectors for which you have data? Yes. Propellers have flown off the end of crankshafts, wheels have departed their axles, elevator push-rods have become disconnected. We read about and ponder these events . . . did any one of these FEMA prompt recommendations for dual engines, an extra landing gear strut and wheel or perhaps splitting the elevator into two halves with independent pushrods? The rational response to such stories is to move avoidance for root cause into prominent positions for attention to detail. I've observed many times in these writings that the greatest risk to the airborne mission is the human element; a risk for missing/ignoring critical fundamentals. Can we deduce what attention to detail is needed to make a battery as reliable as your prop bolts? Bob . . . ________________________________ Message 15 ____________________________________ Time: 09:08:34 AM PST US From: Fred Klein Subject: Re: AeroElectric-List: EXP 2 Bus workaround Bob...you asked: > Is anyone flying this combination of hardware? I asked a pal flying a RAM Sube powered Europa the following questions: >> In your bird, have you ever stopped your engine in flight? >> >> .If so, did the prop stop or windmill? >> >> If the prop stopped, how did you get it spinning again? >> >> Can you spin your starter w/ the Master Switch off? >> >> If not, would you like to be able to? ...and got this reply...not much help unfortunately. Fred > Hi Fred - no I've never stopped it. I thought about flying to an aiport 40 miles north that has an 12000 ft runway and climb to 10000 ft at 6 AM when no traffic was around and turn it off but haven't done it yet. > > I can turn everything off but the fuel pumps and ignition and the engine will run but I never thought of whether the starter > would work - duh!! > > I'll have to check that and get back to you. I need to see if the trim works with everything turned off as well. I'm wondering if with the ac trimmed for cruise whether I would still have enough elevator for the landing flare. > > > XXXX > > From: fklein@orcasonline.com > Subject: a Europa query > Date: Fri, 25 Oct 2013 22:04:53 -0700 > To: XXXX@hotmail.com > > XXXX > > In your bird, have you ever stopped your engine in flight? > > .If so, did the prop stop or windmill? > > If the prop stopped, how did you get it spinning again? > > Can you spin your starter w/ the Master Switch off? > > If not, would you like to be able to? > > > Sorry for all the questions...they are a consequence of an online conversation I'm having with Bob Nuckolls at AeroElectric-list...excerpt below: > > > > (8) Starter can control from main bus. > > True...and...w/ my particular combination of engine, reduction ratio, propeller, and aircraft performance envelope, although I THINK that with engine out, prop would windmill sufficient to restart engine, if Master switch was OFF, I'd like to be able to spin the starter...that was the INTENT of what the diagram shows...What do you think?...I'm unsure as to whether or not the wiring diagram allows for that to happen. > > Is anyone flying this combination of hardware? How much does > IAS need to be reduced to stop a windmilling prop? The few > times I stopped the prop on a TC airplane I had to really > work at it. The idea that one needs access to a starter > motor in flight is mostly without foundation. This is a > fact you need to resolve for your harware combination. > > Thanks once again for your help, > > Fred ________________________________ Message 16 ____________________________________ Time: 09:59:29 AM PST US From: Fred Klein Subject: Re: AeroElectric-List: EXP 2 Bus workaround On Oct 26, 2013, at 8:49 AM, Ken wrote: > > > Is anyone flying this combination of hardware? How much does > > IAS need to be reduced to stop a windmilling prop? The few > > times I stopped the prop on a TC airplane I had to really > > work at it. The idea that one needs access to a starter > > motor in flight is mostly without foundation. This is a > > fact you need to resolve for your harware combination. > > Somewhat different hardware but indicative. With a 1.92 gear ratio and a 3 bladed 72" non-tapered warp prop my ej22 windmills down to below 40 knots. However if I do intentionally stop it (difficult to do with a best glide speed of about 65 knots), a 120 knot dive is insufficient to get a restart. More interesting was that unlike many airplanes, my Rebel has about the same glide ratio whether windmilling or stopped which surprised me. Obviously I do not have one of the sprag clutch type arrangements that have been so troublesome... Ken...interesting...my PSRU ratio is 1.9 to 1.0 and I too do not have a sprag clutch...Fred ________________________________ Message 17 ____________________________________ Time: 10:10:00 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround >>>Can you spin your starter w/ the Master Switch off? Why would you want access to the starter with the master switch off? Under what conditions would you first have the switch off and then find that the engine has assumed a condition that needs encouragement to get running again? Assuming that the engine is at risk for doing such a thing, what prevents you from turning the master switch back on? Bob . . . ________________________________ Message 18 ____________________________________ Time: 10:30:13 AM PST US From: Fred Klein Subject: Re: AeroElectric-List: EXP 2 Bus workaround On Oct 26, 2013, at 10:09 AM, Robert L. Nuckolls, III wrote: >>>> Can you spin your starter w/ the Master Switch off? > > Why would you want access to the > starter with the master switch off? > Under what conditions would you first > have the switch off and then find that > the engine has assumed a condition that > needs encouragement to get running again? > Assuming that the engine is at risk for > doing such a thing, what prevents you > from turning the master switch back on? Bob...my imagination knows no limits...I'm thinkin the Master's off after detecting smoke and acrid smells coming from the panel...I'm wanting to avoid the risk of flippin the Master back on and exacerbating the situation which caused me to flip it off in the first place. Fred ________________________________ Message 19 ____________________________________ Time: 10:57:28 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround >Bob...my imagination knows no limits...I'm thinkin the Master's off >after detecting smoke and acrid smells coming from the panel...I'm >wanting to avoid the risk of flippin the Master back on and >exacerbating the situation which caused me to flip it off in the first place. Okay, so that's a really big failure or a combination of more than one failure giving you both Smoke + engine quits. If you've suffered an event that stops the engine AND smells bad . . . well . . . The configuration on which we're sifting the sands will allow you to turn off every switch except Engine A without killing the engine electrically. Hmmm . . . perhaps Engine A needs to run from the battery, Engine B from the main bus. Now, the statement I made above is true. Even so, unless you've got a clutched PRSU then you're not going to need the starter anyhow. If the engine has lost power due to same event that's causing smoke . . . it's likely that mitigation of risk for that cause is far outside the manipulation of any switches. Bob . . . ________________________________ Message 20 ____________________________________ Time: 11:22:18 AM PST US From: Fred Klein Subject: Re: AeroElectric-List: EXP 2 Bus workaround On Oct 26, 2013, at 10:56 AM, Robert L. Nuckolls, III wrote: > Even so, unless you've got a clutched PRSU then you're > not going to need the starter anyhow. If the engine > has lost power due to same event that's causing smoke > . . . it's likely that mitigation of risk for > that cause is far outside the manipulation of any switches. Bob...I wouldn't disagree with you. The origin of this question arose when you noted that my Revision XX diagram showed the starter switch fed from the engine (sorry, MP) bus rather than the main bus...I still don't see the down side if I were to do this. Fred ________________________________ Message 21 ____________________________________ Time: 11:37:05 AM PST US From: Bob McCallum Subject: RE: AeroElectric-List: EXP 2 Bus workaround Fred; Not meaning to be critical or judgmental, but your "properly designed" and maintained electrical system has somehow found a way to generate "smoke in the cockpit" and you've turned off the master switch. So far so good. The electrical problem (or fire) has progressed to the point of stopping the engine and now you want to be further distracted by operating the starter to turn over the failed engine rather than to "FLY THE AIRCRAFT" to a controlled landing ???? In order to stop, the engine must have been denied either fuel, spark or mechanical integrity, and for it to restart you must determine and restore whichever element is missing before the starter will be of any use. (and you've had to aerodynamically stall the airframe to stop the engine's wind milling rotation) With all the redundancies and complexities you're proposing you're unlikely to troubleshoot and solve the problem in the air. It's excellent to think up and have a solution for the various scenarios, but at some point you need to follow the KISS principle and not layer one "what if" on top of another. The likelihood of two or more failures on any one flight on a properly designed and maintained aircraft are exceeding unlikely. By all means design for any single "what if" or failure you can possibly conceive, but to layer one on top of another on top of another and try to have a work-around is just going to increase the likelihood of a problem not decrease it. Just my unsolicited two cents which you're quite entitled to delete or ignore (or deposit in the bank if you so desire) Bob McC _____ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Fred Klein Sent: Saturday, October 26, 2013 1:30 PM Subject: Re: AeroElectric-List: EXP 2 Bus workaround On Oct 26, 2013, at 10:09 AM, Robert L. Nuckolls, III wrote: Can you spin your starter w/ the Master Switch off? Why would you want access to the starter with the master switch off? Under what conditions would you first have the switch off and then find that the engine has assumed a condition that needs encouragement to get running again? Assuming that the engine is at risk for doing such a thing, what prevents you from turning the master switch back on? Bob...my imagination knows no limits...I'm thinkin the Master's off after detecting smoke and acrid smells coming from the panel...I'm wanting to avoid the risk of flippin the Master back on and exacerbating the situation which caused me to flip it off in the first place. Fred ________________________________ Message 22 ____________________________________ Time: 12:26:14 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround At 01:21 PM 10/26/2013, you wrote: >On Oct 26, 2013, at 10:56 AM, Robert L. Nuckolls, III wrote: > >>Even so, unless you've got a clutched PRSU then you're >> not going to need the starter anyhow. If the engine >> has lost power due to same event that's causing smoke >> . . . it's likely that mitigation of risk for >> that cause is far outside the manipulation of any switches. > >Bob...I wouldn't disagree with you. > >The origin of this question arose when you noted that my Revision XX >diagram showed the starter switch fed from the engine (sorry, MP) >bus rather than the main bus...I still don't see the down side if I >were to do this. You're still wrapped around the axles of distraction. Let's get your list of loads spread out on the hypothetical architecture I published . . . and sift the FEMA/operational sands for that configuration. Then we can begin to study a means by which the EXP-Bus can morph into the same architecture. It may be that the starter switch gets powered from someplace different simply because you've run out of polyfuses on a particular bus. But downside or upside cannot be discussed until after roll-call. I have a finite amount of time to offer to this process . . . Bob . . . ________________________________ Message 23 ____________________________________ Time: 12:38:55 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: EXP 2 Bus workaround At 01:36 PM 10/26/2013, you wrote: >Fred; > >Not meaning to be critical or judgmental, but your "properly >designed" and maintained electrical system has somehow found a way >to generate "smoke in the cockpit" and you've turned off the master >switch. So far so good. >The electrical problem (or fire) has progressed to the point of >stopping the engine and now you want to be further distracted by >operating the starter to turn over the failed engine rather than to >"FLY THE AIRCRAFT" to a controlled landing ???? Gently my friend. Members here on the is are, for the most part, not aviation professionals. Fewer still have a grasp on the materials, processes and what-if analysis that goes into crafting the elegant solution. There was a time when Z-19 was considered a 'solution' and to be sure, every feature on it operates in a predicable manner with no surprises. Fred's willingness to participate in this exercise has prompted a review of the ideas on which Z-19 stands along with brain-storming for simpler alternatives based on better ideas. Fred has mentioned that a friend of his opined that many band-aid-on-top-of-band-aid designs on airplanes to be products of ignorance and poor logic. Yup, those things happen. I've watched it my whole career in situations where I was one of many and with little influence. It doesn't even take a design by committed/regulation to produce an accident waiting to happen. Review the materials I posted on the N811HB accident. Many individuals who monitor the List have expressed a reluctance to post lest they become targets of words that fall outside the realm of entertaining and persuasive information. This is a classroom and it's my greatest wish that people carry knowledge out the door that adds value to their aviation experience. Bob . . . ________________________________ Message 24 ____________________________________ Time: 12:51:57 PM PST US Subject: AeroElectric-List: Re: EXP 2 Bus workaround From: "user9253" I have learned a lot in your classroom. Thanks Bob. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=411476#411476 ________________________________ Message 25 ____________________________________ Time: 12:54:08 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: EXP 2 Bus workaround At 02:51 PM 10/26/2013, you wrote: > >I have learned a lot in your classroom. Thanks Bob. . . . and you've been an honorable participant for which I thank YOU. Bob . . . ________________________________ Message 26 ____________________________________ Time: 01:21:34 PM PST US From: Bob McCallum Subject: RE: AeroElectric-List: EXP 2 Bus workaround _____ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Saturday, October 26, 2013 3:38 PM Subject: RE: AeroElectric-List: EXP 2 Bus workaround At 01:36 PM 10/26/2013, you wrote: Fred; Not meaning to be critical or judgmental, but your =13properly designed=14 and maintained electrical system has somehow found a way to generate =13smoke in the cockpit=14 and you=12ve turned off the master switch. So far so good. The electrical problem (or fire) has progressed to the point of stopping the engine and now you want to be further distracted by operating the starter to turn over the failed engine rather than to =13FLY THE AIRCRAFT=14 to a controlled landing ???? Gently my friend. Was trying to be. If it came across differently, that was not the intention. I apologize. Members here on the is are, for the most part, not aviation professionals. Fewer still have a grasp on the materials, processes and what-if analysis that goes into crafting the elegant solution. There was a time when Z-19 was considered a 'solution' and to be sure, every feature on it operates in a predicable manner with no surprises. Agree Fred's willingness to participate in this exercise has prompted a review of the ideas on which Z-19 stands along with brain-storming for simpler alternatives based on better ideas. And many of his (and others) scenarios point to the areas of potential improvement. Fred has mentioned that a friend of his opined that many band-aid-on-top-of-band-aid designs on airplanes to be products of ignorance and poor logic. Yup, those things happen. Part of the point of my original comment was intended to not lose sight of that philosophy. I've watched it my whole career in situations where I was one of many and with little influence. It doesn't even take a design by committed/regulation to produce an accident waiting to happen. Review the materials I posted on the N811HB accident. Exactly. Many individuals who monitor the List have expressed a reluctance to post lest they become targets of words that fall outside the realm of entertaining and persuasive information. Myself included, but part of the issue is not that the thoughts are intended to be critical or demeaning in any way shape or form but that perhaps the command of English usage or even the degree of articulation is lacking so that comments are misinterpreted. This is a classroom and it's my greatest wish that people carry knowledge out the door that adds value to their aviation experience. Absolutely. I've learned immeasurably through lurking here many years, but as you've stated I'm often reluctant to share because of the fear of misstating my thoughts or verbalizing in a way that is open to misinterpretation. E-mails lack the intonations of a face to face conversation that sometimes conveys as much meaning as the actual words. Bob . . . Once again, if my wording was inappropriate, I apologize. I'll keep quiet now. Bob McC ________________________________ Message 27 ____________________________________ Time: 01:56:19 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: EXP 2 Bus workaround > Gently my friend. >Was trying to be. If it came across differently, that was not the >intention. I apologize. Understand. Perhaps is was the bold, technicolor font that offered a poor first blush. That is a down-side for keyboard communications. We can be deprived of useful communications data when relying on the written word. No value to be shared in 'being quiet' . . . the ideas you proffered were sound. I'm kind of 'stoked with this thread. There's not been a new z-figure in years. This is a good thing that these things get debated. Fred's worries about the smoke+silence failure prompted a thought on my part that perhaps Engine A switch ought to power from the battery with backup being Engine B from the main bus. This is backwards from how we've used the e-bus but it does suggest better human factors for powering down the electrics while leaving the engine up. Bob . . . ________________________________ Message 28 ____________________________________ Time: 02:10:28 PM PST US From: Fred Klein Subject: Re: AeroElectric-List: EXP 2 Bus workaround On Oct 26, 2013, at 11:36 AM, Bob McCallum wrote: > Not meaning to be critical or judgmental, but your =93properly designed=94 and maintained electrical system has somehow found a way to generate =93smoke in the cockpit=94 and you=92ve turned off the master switch. So far so good. Thanks Bob M....I needed that...sometimes my imagination needs a comeuppance and a breath of fresh air...Fred ________________________________ Message 29 ____________________________________ Time: 02:16:27 PM PST US From: Fred Klein Subject: Re: AeroElectric-List: EXP 2 Bus workaround On Oct 26, 2013, at 12:25 PM, Robert L. Nuckolls, III wrote: > You're still wrapped around the axles of distraction. > Let's get your list of loads spread out on the > hypothetical architecture I published . . . and sift > the FEMA/operational sands for that configuration. I'm on it Bob...thanks, Fred ________________________________ Message 30 ____________________________________ Time: 02:20:14 PM PST US Subject: AeroElectric-List: Re: EXP 2 Bus workaround From: "user9253" I have drawn a schematic (attached) for Fred using the EXP Bus. It might not be as good as Bob's designs, but I think it is better than many TC aircraft electrical systems. Fred definitely does not want to take a soldering iron to the circuit board. So I could not make some changes that I would like to. If Fred decides to use my schematic, the only changes that he will have to make will be pulling fast-on connectors off from switches and moving them around. The main feature of this schematic is the addition of a master relay that is in parallel with the battery contactor. Not to worry, this relay can not be energized while starting the engine. The switch, that is normally the master switch, must be off in order to start the engine. This also serves as a theft deterrent because a thief will turn on what he thinks is the master switch, but the engine will not start. The former avionics master switch now controls the battery contactor. Since the new master switch also turns on the alternator field, the former ALT switch can now be used for the second fuel pump. I think that the EXP Bus has enough switches so that additional switches will not have to be added to the panel. Now that I am all done with the schematic and stand back and look at the big picture, I see that in case the EXP Bus smokes, shutting off the master switches will also kill the engine. How to fix that? How about an Engine bus fed by the master relay and also by a diode from the EXP Bus? Comments are welcome. Just do not be too hard on me. :-) Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=411483#411483 Attachments: http://forums.matronics.com//files/fred_exp_2_bus_200.dwg http://forums.matronics.com//files/fred_exp_2_bus_152.pdf ________________________________ Message 31 ____________________________________ Time: 06:50:04 PM PST US From: Jeff Luckey Subject: AeroElectric-List: EXP 2 Bus workaround - Master Solenoid Failure =0A=0AI really enjoy this what-if stuff, so here goes...=0A=0A=0AI'm referr ing to Bob's drawing sent out yesterday afternoon, Z-08_Full.pdf.- It app ears that people are touching on this issue but I have not seen it clearly stated. =0A=0A=0AGiven:=0A1. Stated design goal: To be able to survive any single component failure w/ little or no drama.=0A=0A2. Electrically-depend ent engine=0A=0A3. Engine/prop does not windmill, because of some kind of P SRU =0A4. You are flying w/ Engine A switch On=0A5. Engine B switch Off=0A =0A=0AScenario:=0A1. You are in flight and Main Batt Contactor fails (coil burns up, loose wire, whatever)=0A=0A2. Engine shuts down, prop stops=0A=0A 3. Pilot takes several seconds to gather his thoughts=0A4. Pilot turns Engi ne B switch On - power restored to engine systems except starter=0A=0A5. Pi lot hits starter button to re-light.- Starter inop because failed Main Ba tt Contactor is in series w/ Starter Contactor.=0A6. Forced landing=0A=0A7. Failure to meet design goal - single component failure causes forced landi ============= ________________________________ Message 32 ____________________________________ Time: 08:16:41 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround - Master Solenoid Failure At 08:47 PM 10/26/2013, you wrote: >I really enjoy this what-if stuff, so here goes... > >I'm referring to Bob's drawing sent out yesterday afternoon, >Z-08_Full.pdf. It appears that people are touching on this issue >but I have not seen it clearly stated. > >Given: >1. Stated design goal: To be able to survive any single component >failure w/ little or no drama. >2. Electrically-dependent engine >3. Engine/prop does not windmill, because of some kind of PSRU Turns out not true. >4. You are flying w/ Engine A switch On >5. Engine B switch Off > >Scenario: >1. You are in flight and Main Batt Contactor fails (coil burns up, >loose wire, whatever) Okay . . . >2. Engine shuts down, prop stops No, the alternator doesn't quite producing just because the battery is off line. Further, based on the exchange with Fred/Bob Mc/Bob N I realized that the Engine source coming from the battery should be switched by ENG A. Next iteration will show that. But it's also possible that the pilot would be unaware of the loss of contactor until the next flight when turning battery switch on doesn't light things up. >3. Pilot takes several seconds to gather his thoughts >4. Pilot turns Engine B switch On - power restored to engine systems >except starter . . . but engine IS windmilling >5. Pilot hits starter button to re-light. Starter inop because >failed Main Batt Contactor is in series w/ Starter Contactor. >6. Forced landing >7. Failure to meet design goal - single component failure causes >forced landing :( >8. Thanks for playing... inaccurate statement of premises . . . Bob . . . ________________________________ Message 33 ____________________________________ Time: 08:25:47 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround - Master Solenoid Failure At 10:15 PM 10/26/2013, you wrote: > > >At 08:47 PM 10/26/2013, you wrote: > >>I really enjoy this what-if stuff, so here goes... >> >>I'm referring to Bob's drawing sent out yesterday afternoon, >>Z-08_Full.pdf. It appears that people are touching on this issue >>but I have not seen it clearly stated. Actually, there IS a compelling reason to move the starter button source to the MP-Bus . . . E-bus and Main bus on the EXP-Bus assembly have fixed numbers of protected load-taps. Moving the starter control to the MP-Bus frees up a load-tap on the EXP-Bus. But this still doesn't help you use the starter in-flight with a contator crapped . . . you may be able to energize the starter contactor but because the battery contactor is open, there's no FAT wire power to the contactor. Bob . . . ________________________________ Message 34 ____________________________________ Time: 10:01:39 PM PST US From: Jeff Luckey Subject: Re: AeroElectric-List: EXP 2 Bus workaround - Master Solenoid Failure =0AI believe that some of the installations of the Rotax 912 (and probably other power systems) do not windmill (but the 912 may not be electrically-d ependent ).=0A=0AHowever, I don't think you can categorically say that ALL engines will windmill.- In addition some flight conditions may cause a wi ndmilling prop to stop.- A possible scenario: The pilot becomes task satu rated on the electrical failure and lets the airspeed bleed down and the pr op stops.=0A=0A=0ADooh! I forgot about the alternator - BUT - I've never tr usted an alternator that was not connected to a battery, therefore I would be reluctant to have that as a fall back.=0A=0A=0AWhat about moving the sta rter feed to the battery side of the master?=0A=0A=0A-Jeff=0A=0A=0A=0A_____ ___________________________=0A From: "Robert L. Nuckolls, III" =0ATo: aeroelectric-list@matronics.com =0ASent: Saturday , October 26, 2013 8:15 PM=0ASubject: Re: AeroElectric-List: EXP 2 Bus work around - Master Solenoid Failure =0A =0A=0A--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" =0A=0AA t 08:47 PM 10/26/2013, you wrote:=0A=0A> I really enjoy this what-if stuff, so here goes...=0A> =0A> I'm referring to Bob's drawing sent out yesterday afternoon, Z-08_Full.pdf.- It appears that people are touching on this i ssue but I have not seen it clearly stated.=0A> =0A> Given:=0A> 1. Stated d esign goal: To be able to survive any single component failure w/ little or no drama.=0A> 2. Electrically-dependent engine=0A> 3. Engine/prop does not windmill, because of some kind of PSRU=0A=0A- Turns out not true.=0A=0A > 4. You are flying w/ Engine A switch On=0A> 5. Engine B switch Off=0A> =0A> Scenario:=0A> 1. You are in flight and Main Batt Contactor fails (coil burns up, loose wire, whatever)=0A=0A- Okay . . .=0A=0A> 2. Engine shut s down, prop stops=0A=0A=0A- No, the alternator doesn't quite producing just=0A- because the battery is off line. Further, based on=0A- the e xchange with Fred/Bob Mc/Bob N I realized that=0A- the Engine source com ing from the battery should=0A- be switched by ENG A. Next iteration wil l show that.=0A=0A- But it's also possible that the pilot would be unawa re=0A- of the loss of contactor until the next flight=0A- when turnin g battery switch on doesn't light things up.=0A=0A> 3. Pilot takes several seconds to gather his thoughts=0A> 4. Pilot turns Engine B switch On - powe r restored to engine systems except starter=0A=0A- . . . but engine IS w indmilling=0A=0A> 5. Pilot hits starter button to re-light.- Starter inop because failed Main Batt Contactor is in series w/ Starter Contactor.=0A> 6. Forced landing=0A> 7. Failure to meet design goal - single component fai lure causes forced landing :(=0A> 8. Thanks for playing...=0A=0A- inaccu ============== ________________________________ Message 35 ____________________________________ Time: 10:33:05 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Battery contactor failure At 12:00 AM 10/27/2013, you wrote: >I believe that some of the installations of the Rotax 912 (and >probably other power systems) do not windmill (but the 912 may not >be electrically-dependent ). Only if the fuel is delivered by engine driven pump or gravity. The ignition is electronic driven directly from magnets on the starter ring gear. >However, I don't think you can categorically say that ALL engines >will windmill. In addition some flight conditions may cause a >windmilling prop to stop. A possible scenario: The pilot becomes >task saturated on the electrical failure and lets the airspeed bleed >down and the prop stops. That's s double failure again. Failure tolerant systems with a plan-b do not saturate pilots. >Dooh! I forgot about the alternator - BUT - I've never trusted an >alternator that was not connected to a battery, therefore I would be >reluctant to have that as a fall back. Because you know them to be unreliable or simply don't know. Actually, Cessna and others who opted for the split rocker switch were probably in violation of legacy design goals. Until that time, airplanes flew nicely on either battery, generator or both. When the alternator came along, the airframe guys elected to put alternators on even tho they were not plug-n-play for the failure tolerance offered by generators. The Bonanza and Barons continued to offer alternator- only operations but if I recall correctly, the Liberal airplanes had split rockers. PM alternators are easy to get on-line without a battery and it may well be that belt-driven alternators on a Lycoming are too. They run very fast. I need to get some time on B&C's test bench and run some experiments. >What about moving the starter feed to the battery side of the master? If you're willing to have an always hot feeder to a starter contactor . . . Bob . . . ------------------------------------------------------------------------------------- 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.