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Thread: Magneto 500 Hour Inspection

  1. #11
    Senior Member Jon Delamarter's Avatar
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    Feb 2013
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    Default Re: Magneto 500 Hour Inspection

    One other point of data in this conversation. Some time ago, I think it was in 2015, I got a call from a customer back East who had just experienced SIMULTANEOUS magneto failure on his Sport Cub, which was running the Sensenich/Bendix combo. Thank God the failure occurred at shutdown!
    Jon Delamarter
    Customer Support Manager
    Cub Crafters, Inc.
    jond@cubcrafters.com
    Office (509)367-5200
    Cell (509)833-6993

  2. #12
    Member stroutmail's Avatar
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    May 2018
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    New Freedom, PA
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    Default Re: Magneto 500 Hour Inspection

    Quote Originally Posted by Jon Delamarter View Post
    One other point of data in this conversation. Some time ago, I think it was in 2015, I got a call from a customer back East who had just experienced SIMULTANEOUS magneto failure on his Sport Cub, which was running the Sensenich/Bendix combo. Thank God the failure occurred at shutdown!
    Sometimes pilots incorrectly assume redundancy guarantees safety. Mags are a lot more complicated than many assume---I read the following AWB from Australia "FAA" with great interest. Lots can go wrong. http://caa.gov.il/index.php?option=c...id=669&lang=he

  3. #13
    Member stroutmail's Avatar
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    May 2018
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    New Freedom, PA
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    Default Re: Magneto 500 Hour Inspection

    Just some feedback that may be of help to others.. at 456 hours on my S/N 28 CC11-100 Sport Cub, I went ahead and replaced the Bendix mags with new Slicks--ordered from QAA. The A&P was concerned about axial end play and found no spec in the Continental Overhaul Manual's Table of Limits. Many phone calls to QAA, Slick, Cubcrafters and Continental and much discussion later--the axial end play is supposed to be around 0.020" and the drive gear used for the Bendix mag is the same as to be used on the Slicks. End play is "necessary" to insure proper operation of the impulse drive. Still---according to Continental Tech Support--this "necessary end play" is not written in the Overhaul Manual or other bulletin that they were aware of---Joe Logie at Slick turned out to be the best source of info. Seems this info is "known to many" but not to all.

    A careful inspection of the mag drive gears and the mating engine mounted gear showed no wear pattern and no spalling--looked almost new. (My guess is that my plane has spent most of it's life with the 52 cartridge in the Sensenich Ground Adj Prop and RPM never exceeds 2500... lower RPM...less harmonic resonance--or none.)

    Next came some concern over the hold down clamps---the ones from Slick are a bit larger than ones used on older 0-200-A engines. The new ones from Slick hung over the edge of the machined boss on the engine. Solution, used some older ones--slightly smaller that fit the machined boss perfectly.

    Mag change part of 500 hour Mag Inspection/Overhaul which coincided with my 2019 Annual.

    Plane had a small vibration at 1900 RPM all during 2018. Thought it was perhaps prop related (There has been some discussion in the forums.) but turns out the right lower engine mount "attenuator" had failed--cracked in half. (This is the silicone colored part that slips over the spacer inside the mount assembly.) Both lower mounts had sagged. We replaced all the engine mount "soft" parts with new items and using new AN bolts and nuts--reused other metal parts.

    I had planned to change from the 52 cartridge to the 50, but decided to run with the Slick mags leaving the prop alone to see if there are any performance differences. (I don't expect any.) The plane takes off in a very short distance here at 600 MSL in Central Pennsylvania and is overall a great performer (has performance exhaust) so I may stay with the 52.
    Last edited by stroutmail; 06-21-2019 at 10:07 AM.

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