AeroElectric-List Digest Archive

Sun 10/27/13


Total Messages Posted: 17



Today's Message Index:
----------------------
 
     1. 02:32 AM - Re: EXP 2 Bus workaround - Master Solenoid Failure (BobsV35B@aol.com)
     2. 07:19 AM - Re: EXP 2 Bus workaround - Master Solenoid Failure (Ken)
     3. 07:30 AM - Re: Battery contactor failure (Jeff Luckey)
     4. 07:39 AM - Re: Re: EXP 2 Bus workaround (Sacha)
     5. 07:54 AM - Re: EXP 2 Bus workaround - Master Solenoid Failure (BobsV35B@aol.com)
     6. 08:07 AM - Re: Re: EXP 2 Bus workaround (Jeff Luckey)
     7. 08:14 AM - Re: Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
     8. 08:30 AM - Accident library addition (Robert L. Nuckolls, III)
     9. 08:53 AM - Contactors (Eric M. Jones)
    10. 08:58 AM - Re: EXP 2 Bus workaround (user9253)
    11. 09:54 AM - Re: EXP 2 Bus workaround (user9253)
    12. 11:06 AM - Re: Re: EXP 2 Bus workaround (Sacha)
    13. 11:06 AM - Re: Re: EXP 2 Bus workaround (Sacha)
    14. 11:14 AM - Re: Re: EXP 2 Bus workaround (Robert L. Nuckolls, III)
    15. 11:23 AM - Re: Re: hypothetical question (Rob Housman)
    16. 11:37 AM - Re: Re: EXP 2 Bus workaround (Bob McCallum)
    17. 01:37 PM - Re: Alternator without a Battery (Sacha)
 
 
 


Message 1


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    Time: 02:32:48 AM PST US
    From: BobsV35B@aol.com
    Subject: Re: EXP 2 Bus workaround - Master Solenoid Failure
    Good Morning All, I have not followed all of this thread, but agree that not all engines windmill like our friendly Continentals and Lycomings. I have about twenty hours flying a Legend Cub powered by the Jabiru engine. It is a nice smooth running engine, but if it runs out of fuel or the mags are shut off, the prop stops! Happy Skies, Old Bob In a message dated 10/27/2013 3:32:26 A.M. Central Daylight Time, jluckey@pacbell.net writes: 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 ). 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. 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. What about moving the starter feed to the battery side of the master? -Jeff


    Message 2


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    Time: 07:19:56 AM PST US
    From: Ken <klehman@albedo.net>
    Subject: Re: EXP 2 Bus workaround - Master Solenoid Failure
    Old Bob Just curious whether you've tried it and whether it was the 4, 6, or 8 cylinder jab? (You probably have tried it or talked to someone who has if you posted it.) There were lots of opinions that my geared setup would not windmill but it most certainly does. More opinions than facts as is often the case on the internet. For sure there are some known engines/reduction units that do not windmill. (break) I like the concept of minimal connections and components in the truly essential engine circuits so I like feeding them directly from battery busses. Engine stoppage occurs far more often than the need to kill every last electric circuit in a dire emergency. (I'm sure that a significant percentage of engine out landings/crashes occur with the battery master still on anyway). I favor feeding "keep it running" engine circuits directly from battery busses. Sure, route backups through the master if one wishes but not primary circuits. Then regardless of windmilling, I see little need to wire such that an engine can be cranked with the master off or with a failed battery contactor. That caters to multiple failures and raises other safety concerns IMO. Ken On 27/10/2013 5:31 AM, BobsV35B@aol.com wrote: > Good Morning All, > I have not followed all of this thread, but agree that not all engines > windmill like our friendly Continentals and Lycomings. I have about > twenty hours flying a Legend Cub powered by the Jabiru engine. It is a > nice smooth running engine, but if it runs out of fuel or the mags are > shut off, the prop stops! > Happy Skies, > Old Bob > In a message dated 10/27/2013 3:32:26 A.M. Central Daylight Time, > jluckey@pacbell.net writes: > > > 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 ). > > 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. > > 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. > > What about moving the starter feed to the battery side of the master? > > -Jeff > >


    Message 3


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    Time: 07:30:58 AM PST US
    From: Jeff Luckey <jluckey@pacbell.net>
    Subject: Re: Battery contactor failure
    =0A=0AMy comment is italics=0A=0A=0A-Jeff=0A=0A=0A_________________________ _______=0A From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com> =0ATo: aeroelectric-list@matronics.com =0ASent: Saturday, October 26, 2013 9:32 PM=0ASubject: AeroElectric-List: Battery contactor failure=0A =0A=0A-- bob@aeroelectric.com>=0A=0AAt 12:00 AM 10/27/2013, you wrote:=0A=0A> I beli eve that some of the installations of the Rotax 912 (and probably other pow er systems) do not windmill (but the 912 may not be electrically-dependent ).=0A=0AOnly if the fuel is delivered by engine driven pump=0Aor gravity. T he ignition is electronic driven directly=0Afrom magnets on the starter rin g gear.=0A=0A> However, I don't think you can categorically say that ALL en gines will windmill.- In addition some flight conditions may cause a wind milling prop to stop.- A possible scenario: The pilot becomes task satura ted on the electrical failure and lets the airspeed bleed down and the prop stops.=0A=0AThat's s double failure again. Failure tolerant systems=0Awith a plan-b do not saturate pilots.=0A=0ADisagree - There is way too much cas e history of pilots becoming distracted, over seemingly trivial issues, to suggest that you can write-off this scenario.=0A=0A> Dooh! I forgot about t he alternator - BUT - I've never trusted an alternator that was not connect ed to a battery, therefore I would be reluctant to have that as a fall back .=0A=0A- Because you know them to be unreliable or simply=0A- don't kno w. Actually, Cessna and others who opted=0A- for the split rocker switch were probably in violation=0A- of legacy design goals.=0A=0AOnce upon a t ime waaay back in the late 70s I had seen a few alternators lose voltage re gulation when battery became disconnected.- This was in the marine enviro nment.- Regulators are most certainly better now but those experiences ha ve stuck with me.=0A=0A- Until that time, airplanes flew nicely on either =0A- battery, generator or both. When the alternator=0A- came along, th e airframe guys elected to put=0A- alternators on even tho they were not plug-n-play=0A- for the failure tolerance offered by generators.=0A=0A- The Bonanza and Barons continued to offer alternator-=0A- only operation s but if I recall correctly, the Liberal=0A- airplanes had split rockers. =0A=0A- PM alternators are easy to get on-line without a=0A- battery an d it may well be that belt-driven alternators=0A- on a Lycoming are too. They run very fast. I need to=0A- get some time on B&C's test bench and r un some experiments.=0A=0A> What about moving the starter feed to the batte ry side of the master?=0A=0A- If you're willing to have an always hot fee der to a=0A- starter contactor . . .=0A=0AAre there reasons to not do thi s?Is that any worse than having an always hot feed to the "main" bus?=0A- ==


    Message 4


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    Time: 07:39:11 AM PST US
    Subject: Re: EXP 2 Bus workaround
    From: Sacha <uuccio@gmail.com>
    > If you're willing to have an always hot feeder to a > starter contactor . . . That doesn't sound very safe when you're on he ground. Keys are out, master e tc off, someone is by the prop and someone else accidentally actuates the st arter by pushing the starter button or whatever. Even if the engine doesn't s tart you can still do some damage.


    Message 5


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    Time: 07:54:59 AM PST US
    From: BobsV35B@aol.com
    Subject: Re: EXP 2 Bus workaround - Master Solenoid Failure
    Good Morning Ken You wrote: "Just curious whether you've tried it and whether it was the 4, 6, or 8 cylinder jab? (You probably have tried it or talked to someone who has if you posted it.)" I flew the airplane over twenty hours in less than a week flying off a lot of the required time for an experimental category airplane. It was at the factory in Texas, so I did have the factory folks to help with any difficulties encountered. The runways were long and the traffic was nil so I had no hesitation to do things that would cause the engine to quit. I never had to make a "forced" landing as the starter always worked, but I did shut off the fuel at least once just to check how well it would restart. Same for shutting off the ignition. It also quit at low speeds if the idle RPM was set on the low side. To get a nice short Cub style three point landing, the idle RPM had to be so low that the engine would quit and the prop would stop turning well before touchdown. I do not recall the exact airspeed at which the prop would stop, but it was not much below sixty mph. It has been over five years since I did that test flying. That was the only feature of the Jabiru install that I really did not care for. If it were up to me, I would have used the O-200 Continental or an O- 320 Lycoming. The high idle made for longer than necessary ground roll out and/or excessive use of the brakes. It is a 6 cylinder 3300 Jabiru with the BMW carburetor. Happy Skies, Old Bob


    Message 6


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    Time: 08:07:04 AM PST US
    From: Jeff Luckey <jluckey@pacbell.net>
    Subject: Re: EXP 2 Bus workaround
    =0A=0A=0A=0A________________________________=0A From: Sacha <uuccio@gmail.c om>=0ATo: "aeroelectric-list@matronics.com" <aeroelectric-list@matronics.co m> =0ASent: Sunday, October 27, 2013 6:24 AM=0ASubject: Re: AeroElectric-Li st: Re: EXP 2 Bus workaround=0A =0A=0A=0A-If you're willing to have an al ways hot feeder to a=0A>-starter contactor . . .=0A=0AThat doesn't sound very safe when you're on he ground. Keys are out, master etc off, someone i s by the prop and someone else accidentally actuates the starter by pushing the starter button or whatever. Even if the engine doesn't start you can s till do some damage. =0A=0AThat is not the case, with the master off you wi ll not be able to crank as the coil circuit for starter contactor will not 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 -=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D


    Message 7


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    Time: 08:14:44 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: EXP 2 Bus workaround
    >That doesn't sound very safe when you're on he ground. Keys are out, >master etc off, someone is by the prop and someone else accidentally >actuates the starter by pushing the starter button or whatever. Even >if the engine doesn't start you can still do some damage. There are TWO inputs to a starter contactor. FAT wire power to operate the motor and small wire power through the starter switch to energize the contactor coil. One COULD consider an always hot FAT wire that bypasses the battery contactor while shutting down the power source for the starter push-button. But this is contrary to legacy design goals for achieving max-dark on an electrical system when all switches are OFF. Bob . . .


    Message 8


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    Time: 08:30:55 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Accident library addition
    I was made aware of this incident involving a LA235 that appeared to have suffered electrical system difficulties. http://tinyurl.com/mwo3f4x The NTSB said 'everything was working but the battery was dead.' This engine seems to have run out of fuel because transfer pumps were deprived of power to bring fuel to a header tank. The documents are markedly devoid of a finding for root cause. The narrative paints and image of an owner/pilot who hasn't got a clue for the significance of "anomalies" in system operation. The airplane had been begging for help for perhaps two months before the accident. His notion of making the airplane flightworthy was to install a freshly charged battery . . . that failed minutes after takeoff. His header tank must have been nearly dry at takeoff which begs the question as to his use of a checklist for verification if header tank fuel and functionality of the transfer pumps were working and the altrrnator was charging the battery. As near as we can tell, nothing was broken. No parts had failed to do their intended task except that a working alternator failed to charge a battery. This accident has more to teach about the technical skills and operational philosophy of the owner/operator than about the design of an electrical system. Bob . . .


    Message 9


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    Time: 08:53:11 AM PST US
    Subject: Contactors
    From: "Eric M. Jones" <emjones@charter.net>
    The requirement for a main battery contactor comes from the FAA's requirement to have the main battery disconnected "by one hand" in the event of a forced landing. Cutting off the main source of electrical energy should reduce the chance of ignition one supposes. NASCAR and various racing groups have the same problem but they usually have decided that a contactor failure is to be avoided by the elimination of electrical coil-type contactors, instead choosing rugged mechanical switches like "Flaming River Battery Switches". So keep in mind: 1) A contactor won't fail if you don't have one. 2) A contactor by regulations only has to open, not close. Sort of like a parachute. 3) Really big switches can be used instead of small switches and contactors. My Grandfather's Chevy had a starter footswitch. Still seems like a good idea. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones(at)charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=411531#411531


    Message 10


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    Time: 08:58:34 AM PST US
    Subject: Re: EXP 2 Bus workaround
    From: "user9253" <fransew@gmail.com>
    I figured out the reason for D3 in the EXP2Bus (questioned in a previous post). When the master switch is open, D3 prevents current from flowing in series through the master contactor coil and into the EXP2Bus. I drew a new schematic (pdf attached) using the EXP2Bus and also a separate Engine Bus. I also have a dwg version if anyone is interested. The Engine bus is fed from two paths so that any one failure will not cut power to the engine. The EXP2Bus also has outputs that can supply engine loads. An endurance bus is not needed because the SkyView and GPS both have internal backup batteries. The COM radio is powered by either the EXP2Bus or by the ENG bus through dual diodes inside of the EXP2Bus (CLRNC DEL input). Comments and suggestions welcome. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=411532#411532 Attachments: http://forums.matronics.com//files/exp2_and_eng_bus_548.pdf


    Message 11


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    Time: 09:54:57 AM PST US
    Subject: Re: EXP 2 Bus workaround
    From: "user9253" <fransew@gmail.com>
    Bob, What are your thoughts on having a separate switch for the alternator field versus using the second half of a double pole master switch? I know that your designs use a progressive transfer switch with the center position battery only with the alternator off. But I am thinking about the EXP2Bus (or any electrical system) that does not have the progressive transfer switch, just a common DPDT switch. Assuming the pilot has a plan B, for instance an E-Bus, she could shut off the one DPDT Master-Alt switch in the event of an alternator failure. Most likely the pilot will want the master off anyway to conserve the battery. Or is it better to have a separate Alt switch? Thanks, Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=411535#411535


    Message 12


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    Time: 11:06:26 AM PST US
    Subject: Re: EXP 2 Bus workaround
    From: Sacha <uuccio@gmail.com>
    >>> If you're willing to have an always hot feeder to a >>> starter contactor . . . >> >> That doesn't sound very safe when you're on he ground. Keys are out, mast er etc off, someone is by the prop and someone else accidentally actuates th e starter by pushing the starter button or whatever. Even if the engine does n't start you can still do some damage. >> >> That is not the case, with the master off you will not be able to crank a s the coil circuit for starter contactor will not be powered. See dwg. You're correct, sorry I spoke before i took a look at the actual circuit. Sacha Ps. What is the issue with wether the prop windmills or stops? Is it that t he engine is easier to restart if the prop is windmilling?


    Message 13


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    Time: 11:06:40 AM PST US
    Subject: Re: EXP 2 Bus workaround
    From: Sacha <uuccio@gmail.com>
    >>> That doesn't sound very safe when you're on he ground. Keys are out, master etc off, someone is by the prop and someone else accidentally actuates the starter by pushing the starter button or whatever. Even if the engine doesn't start you can still do some damage. >> >> There are TWO inputs to a starter contactor. >> FAT wire power to operate the motor and >> small wire power through the starter switch >> to energize the contactor coil. One COULD >> consider an always hot FAT wire that bypasses >> the battery contactor while shutting down >> the power source for the starter push-button. >> But this is contrary to legacy design goals >> for achieving max-dark on an electrical system >> when all switches are OFF. >> Got it, thanks!


    Message 14


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    Time: 11:14:41 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: EXP 2 Bus workaround
    At 11:53 AM 10/27/2013, you wrote: > >Bob, >What are your thoughts on having a separate switch for the >alternator field versus using the second half of a double pole master switch? Depends on how well the alternator performs without a battery. It would be nice to have it run independently of the battery. > I know that your designs use a progressive transfer switch with > the center position battery only with the alternator off. But I am > thinking about the EXP2Bus (or any electrical system) that does not > have the progressive transfer switch, just a common DPDT > switch. Assuming the pilot has a plan B, for instance an E-Bus, > she could shut off the one DPDT Master-Alt switch in the event of > an alternator failure. Most likely the pilot will want the master > off anyway to conserve the battery. The ideas behind the e-bus was to offer a means by which everything not needed during en route flight, i.e. cruising for an hour or more watching the ground go by. This includes the battery contactor which draws .8 to 1.0 amps by itself . . . as much as one or two more radios. > Or is it better to have a separate Alt switch? It's nice to turn battery on leaving alternator off for ground ops. A non-rotating alternator draws about 3A of field current and gets hot. When the system is fitted with crowbar ov protection, then there's a circuit breaker that can be pulled to disable the alternator for maintenance. Some of my earlier drawings were dpdt bat/alt switch + circuit breaker. But there was such a love affair going on over the split rocker switch that I decided to describe a replacement for the same functionality in a toggle switch. Whether or not a separate switch is advised is predicated on alternator performance sans battery. Bob . . .


    Message 15


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    Time: 11:23:09 AM PST US
    From: "Rob Housman" <rob@hyperion-ef.com>
    Subject: Re: hypothetical question
    Are you suggesting that New York to Paris is not a long distance? Some folks thought it was in 1927. Do not archive Best regards, Rob Housman Europa XS A070 Rotax 914 Airframe complete Avionics a work in progress -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Eric M. Jones Sent: Wednesday, October 23, 2013 7:46 AM Subject: AeroElectric-List: Re: hypothetical question --> <emjones@charter.net> Let's take a loop 4 meters in diameter and put 200A through it. The magnet field created is about 0.63 Gauss. This is about the same as the Earth's magnetic field itself. So I wouldn't be too worried about it. It is telling that your friend was a Navy man. The US navy knows more about the Earth's magnetic field than anyone else. Reading the published naval papers on the subject is fascinating. They degauss ships hulls (Philadelphia Experiment!), and even know how the pounding of rough seas changes the magnetism of ships' hulls over time. Aircraft steel tubes magnetize over time and compass compensation is periodically figured in. But of course, the Earth's magnetic field and its consistency is not great either. For local use this is okay. No pilot ever used a compass for long distances. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones(at)charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=411199#411199


    Message 16


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    Time: 11:37:05 AM PST US
    From: Bob McCallum <robert.mccallum2@sympatico.ca>
    Subject: Re: EXP 2 Bus workaround
    If the prop is windmilling then the starter isn't needed for a restart. All you need is to provide fuel and spark, it already turning. Bob McC _____ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Sacha Sent: Sunday, October 27, 2013 2:05 PM Subject: Re: AeroElectric-List: Re: EXP 2 Bus workaround If you're willing to have an always hot feeder to a starter contactor . . . That doesn't sound very safe when you're on he ground. Keys are out, master etc off, someone is by the prop and someone else accidentally actuates the starter by pushing the starter button or whatever. Even if the engine doesn't start you can still do some damage. That is not the case, with the master off you will not be able to crank as the coil circuit for starter contactor will not be powered. See dwg. You're correct, sorry I spoke before i took a look at the actual circuit. Sacha Ps. What is the issue with wether the prop windmills or stops? Is it that the engine is easier to restart if the prop is windmilling?


    Message 17


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    Time: 01:37:21 PM PST US
    From: "Sacha" <uuccio@gmail.com>
    Subject: Alternator without a Battery
    >From the Rotax Installation Manual, Section 24-00-00, page 7: "A capacitor (see fig. 11, pos 14) of at least 22000 uF/25V is necessary to protect the correct function of regulator and to flatten voltage. The regulator is not designed to store any electrical charge. If for any reason the battery or bus system is disconnected from the regulator while the engine is running (i.e. the master switch is shut off) the capacitor will safely absorb and dissipate the electrical charge produced by the generator. Otherwise the regulator would be damaged." Thanks Rick. I had missed your post. sacha Do not archive




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