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Thread: Propeller handling with Electronic Ignition

  1. #1
    Neil's Avatar
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    Propeller handling with Electronic Ignition

    In the topic regarding the parking position of wood propellers the mention of turning the prop backwards in the interest of safety came up. This worked with impulse coupling mags but now there is a threat to safety as long as aviators believe turning backwards is safe.

    The Electronic Ignitions will fire in either rotation. I'm not familiar with all of them but of those I am, they will fire in either direction of rotation. Also the notion that if the master is off the ignition is off is False. If it is wired as in the Lightspeed manual the ignition circuit is not run through the primary buss. The ignition is wired directly from the battery to a pair of circuit breakers and on to the system components. This is done so the engine will continue to run in the event there is some sort of emergency that requires the master be shut off. An option on this system is a backup battery that will power one of the ignitions in the event of a primary battery failure. The secondary battery is often mounted in another location and disconnecting the primary battery would not make the ignition safe unless the breakers for both of the ignitions were pulled.

    These systems work well, but they present a new element of danger in propeller handling. Like most any thing else that is not part of the "Old School Common Knowledge" an awareness of their workings should be brought forth.

  2. #2
    Cary's Avatar
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    Of course, the basic rule of propeller safety is to assume, always, that it is "hot", so that any movement could potentially cause the engine to start or at least kick over. Whether electronic or magneto, that's always a possibility. I'm always bothered by the macho pictures of pilots, showing them draped around the propeller as if to look "cool". If you have to be near the prop, such as to attach a towbar, you must be aware of the danger and do what you can to minimize it--like not move the prop while you're in a bad position to move back out of its arc.

    Cary
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    put out my hand and touched the face of God." J.G. Magee

  3. #3

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    I have one pmag and one LSE-i! My inspector hates that. Says ya have to have one mag! Pmag has internal alternator plus battery. LSE-i has battery & back up battery will light to tell me charge on back up battery.

  4. #4

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    Says ya have to have one mag!
    That is almost funny. Mags are so unreliable compared to more recent technology that you HAVE to have 2 in order to be safe! Without having actual data handy, I would almost (key word being "almost" ) state that I would rather have a single, battery backed electronic ignition than 2 mags.

    Having 2 electronic ignitions would be FAR better than one mag...but that is just my $0.02.
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  5. #5

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    Perhaps it depends on one's values. I have no experience with aircraft-specific electronic ignition, but what I do know from cars leads me to prefer mags. Electronic ignition tends to give no warnings, at one moment it's running fine, then at the next it's not functioning at all. Mags, on the other hand, usually give lots & lots of warning prior to total failure. In the air, where it is my life on the line ( not merely inconvenience ), I prefer having some warning....

  6. #6
    rwanttaja's Avatar
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    Quote Originally Posted by teknosmurf View Post
    That is almost funny. Mags are so unreliable compared to more recent technology that you HAVE to have 2 in order to be safe! Without having actual data handy, I would almost (key word being "almost" ) state that I would rather have a single, battery backed electronic ignition than 2 mags.

    Having 2 electronic ignitions would be FAR better than one mag...but that is just my $0.02.
    My ~18-year homebuilt accident database shows 28 accidents specifically attributable to a mag-based ignition system, vs. 22 to electronic ignitions.

    In those 28 mag-failure accidents, 22 aircraft had single magnetos. For non-magneto ignitions, the key factor is maintaining electrical power...which, when it happens, negates the advantages of a dual electronic ignition. Here are some NTSB reports and a summary of their Probable Causes, for accidents involving failures of electronic ignition systems.

    SEA02LA069: A partial failure of the electrical (ignition) system and a short to the master electrical switch during cruise flight resulting in a loss of engine power.

    CHI02CA267: The total failure of the engine ignition system, and the unsuitable terrain encountered during the forced landing.

    DEN05LA123: A total electrical failure due to a short in the master relay, causing the main fuse to open.

    LAX05CA310: A loss of engine power due to the failure of the master electrical power switch, which removed power to the electronic ignition.

    LAX05LA319: A loss of engine power due to a loose master ignition relay wire.

    NYC06LA024: Failure of the ignition system, which resulted in a loss of engine power.

    LAX06CA088: A partial loss of engine power due to the engine's electronic control system reverting to a designed reduced power mode of operation.

    SEA06CA080: The loss of engine power due to failure of both electronic ignition systems.

    ATL06LA121: The pilot's failure to maintain ground clearance while maneuvering for a forced landing following loss of engine power.

    ANC06LA130: An electrical short that disabled the electronic ignition system of the airplane's engine during the final approach phase for landing...

    SEA07LA095: A total loss of engine power due to the failure of the primary and secondary electronic control units (ECU's) within the engine's Fully Automated Digital Electronic Control.

    LAX07LA245: A loss of engine power due to a dual ignition system failure.

    DFW08CA079: An unsuccessful precautionary landing due to an electrical system malfunction.

    CEN11CA047: The failure of the ignition system wiring, which resulted in a total loss of engine power.

    WPR12FA059: An electrical or engine electronic problem, which resulted in a loss of engine power

    CEN12LA389: An internal failure of one of the electrical system’s two batteries combined with the inadequate electrical system design, which resulted in a total loss of engine power.

    CEN14LA195: The distributor failure, which resulted in a total loss of engine power during cruise climb.

    CEN15LA132: A fault in the No. 1 engine control module, which disabled the ignition system and resulted in the engine losing power; during the subsequent autorotation, the main rotor rpm was further reduced just before touchdown, which resulted in a hard landing.

    Ron Wanttaja
    Last edited by rwanttaja; 12-28-2016 at 11:59 AM.

  7. #7
    DaleB's Avatar
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    Quote Originally Posted by Tailwheeler Too View Post
    Perhaps it depends on one's values. I have no experience with aircraft-specific electronic ignition, but what I do know from cars leads me to prefer mags. Electronic ignition tends to give no warnings, at one moment it's running fine, then at the next it's not functioning at all. Mags, on the other hand, usually give lots & lots of warning prior to total failure. In the air, where it is my life on the line ( not merely inconvenience ), I prefer having some warning....
    It's true that electronic ignition systems CAN fail abruptly, as can a magneto. However, the last time I personally experienced a failure of an electronic ignition system in a car, plane, motorcycle or anything else was in the late 1980s. And that one didn't quit abruptly; symptoms of an impending failure got progressively worse over a couple of days before it finally quit altogether.

    I have a pair of electronic ignition modules on the Rotax in my RV-12. It doesn't bother me that there are no mags; I haven't heard a lot of reports of Rotax powered planes (and there are a lot of them) falling from the sky due to both ignition modules failing. It doesn't even bother me that I won't be able to hand prop the engine if the battery is dead. I know it's conceivable that the need for electrical power could bite me some day -- as could a busted magneto, so take your pick.

    More to the OP's point, though... I have to rotate the prop through a number of times every time I go to fly. It's an LSA, so of course you have to wind it up first. The ignition modules are both wired through their own power switches and the master, so I use normal caution when doing it... but you still never want to completely trust anything mechanical or electronic. It's just not a good idea.
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  8. #8
    FlyingRon's Avatar
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    Yep, Ron nailed it. What kills the electronic ignition is lack of it being powered. They generally can burn through other failure modes.
    I'd have to say my experience with mag problems is about the same as my experience with charging system problems. But I've certainly had some problems (plug fowling) that I'd never have with the stronger spark with the electronic ign.

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