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Thread: Master Solenoid

  1. #11

    Join Date
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    Idaho
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    Default Re: Master Solenoid

    Quote Originally Posted by rv9ralph View Post
    Victor,
    The Kitfox Aircraft FWF install manual for the 915is shows the circuit from the battery to the Master Solenoid to the Starter Solenoid. The master switch controls the master solenoid, the Rotax supplied starter solenoid is activated from the engine harness.

    Ralph
    Thanks for getting that info. I was planning to take a look the next time I am there.

    Victor
    Building SS7
    915iS
    Garmin G3x

  2. #12
    Senior Member PapuaPilot's Avatar
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    Default Re: Master Solenoid

    Quote Originally Posted by Delta Whisky View Post
    BTW - a nice to have feature is a 12V LED wired to the motor side of the starter solenoid in your panel - to show that the starter solenoid really disconnected when you released the key/start button.
    I did this as a discrete input to the GEA24 on my G3X system. It shows up as a CAS message on the G3X screen.
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  3. #13
    Senior Member PapuaPilot's Avatar
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    Default Re: Master Solenoid

    Quote Originally Posted by VictorV View Post
    Yes. I was planning on doing that.

    Here's what threw me off regarding this issue. The 915is installation manual recommends a battery that can handle 350 Cold Cranking Amps (CCA) which is 350 amps for 30 seconds. It seems like
    an awful lot but I have to go by what Rotax recommends.

    Looking deeper into the specs for the 2 solenoids I referenced earlier, the master solenoid has the following specs:
    - Max inrush is 600 amps
    - Max continuous is 100 amps
    - Max breaking current is 200 amps

    350 CCA is for 30 seconds which is not continuous but not really short-duration either. I'm not exactly sure what "Breaking Current" means
    but it's certainly less than the 350 CCA.

    Victor
    The CCA is a battery rating that is unrelated to the contactor ratings. Rotax is giving you the bare minimum rating for a battery that will properly crank the engine.

    The master solenoid you mentioned here should work fine as long as it is a continuous operation solenoid. The contactor you select needs to be able to handle the highest possible continuous current your plane could have (100A) and the highest possible inrush current (600A), which occurs the moment you activate the starter.
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  4. #14
    kitfoxjim's Avatar
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    Dec 2010
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    Calgary, AB
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    Default Re: Master Solenoid

    I stand corrected....the starter should be in series with the contactor solenoid to enable shut off if there is a failure of push button start or the starter contactor. When checking thats the way mine is wired. I reacted too soon to what looked like easy answer.
    Jim Corner
    KF2 582 1150 hrs
    KF5 O-360 1150 hrs

  5. #15

    Join Date
    Dec 2021
    Location
    Dawson Creek, BC
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    16

    Default Re: Master Solenoid

    Quote Originally Posted by Delta Whisky View Post
    BTW - a nice to have feature is a 12V LED wired to the motor side of the starter solenoid in your panel - to show that the starter solenoid really disconnected when you released the key/start button.

    Im curious why this light is needed?...If the starter solenoid did not disconnect wouldn't you see the prop turning ??...or can they stick just slightly and not turn the prop ?

  6. #16
    Senior Member Eric Page's Avatar
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    Default Re: Master Solenoid

    The problem arises when the starter solenoid sticks after the engine has started. With the engine running -- and no indictor light or CAS message -- there's no indication that the starter remained engaged.
    Eric Page
    Building: Kitfox 5 Safari | Rotax 912iS | Dynon HDX
    Member: EAA Lifetime, AOPA, ALPA
    ATP: AMEL | Comm: ASEL, Glider | ATCS: CTO
    Map of Landings

  7. #17
    Senior Member PapuaPilot's Avatar
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    Default Re: Master Solenoid

    Quote Originally Posted by Eric Page View Post
    The problem arises when the starter solenoid sticks after the engine has started. With the engine running -- and no indictor light or CAS message -- there's no indication that the starter remained engaged.
    I installed a wire to sense an active starter in my Kitfox. It's one of the programmable discreet inputs to the Garmin G3X, which means it says "STARTER" on the screen. It's the first thing I check after the engine starts, before checking oil pressure.

    This problem is real. I had a stuck start contactor happen once in a C-206. The plane actually had an annunciator panel with an LED light. The problem was the LED was in direct sunlight and was not readable after the start. I didn't see it until I had just lifted off the ground so I came back and landed. The starter was trashed, and had to be changed. Another plane in my company, a Kodiak 100 with a PT6 turboprop, had a stuck starter contactor. After shutting off the engine's fuel, turning off the master switch and disconnecting the external power the engine was still cranking! The crew just let it crank till the battery died. It destroyed the main battery, and we had to send the starter/generator off for overhaul. Fortunately the battery didn't explode during the high discharge.

    It is super simple to add in an LED light or wire it into a screen. You just need to add a wire on the output side of the starter contactor. The wire is "hot" or active when the starter is engaged.
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  8. #18
    Senior Member
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    wales,ny
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    Default Re: Master Solenoid

    Great information Phil, to be honest something I hadn't thought about till reading this thread. An easy solution and I will add the annunciator right next to my engine monitor where my eyes go immediately after engine start anyway. Thanks Bruce N199CL

  9. #19
    Senior Member
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    Mapleton,UT
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    Default Re: Master Solenoid

    Just fyi for those using the vpx and g3x, the vpx sends a CAS message when the starter is engaged.
    Dustin Dickerson

    Building 7ss STI x 2
    Oratex
    29" shock monster
    EP912STI 155hp
    Garmin
    N33TF......FLYING!
    N53TF......FLYING!

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