fbpx
Login

 

Jump to Forum..

Momentary start power switch or not?

in 912iS Technical Questions 8 years ago

  • Re: Momentary start power switch or not?

    by » 8 years ago

    Thank you for the diagram Bill. It would be great if we could do this with a Two pole switch but I think we need Three poles because in addition to the starter and twelve volt lines we also have to connect the two grounds.

    I can't find a three pole mil spec switch just the 4 pole switch which is eaton/microswitch 4TL1 - 50 or (MS 27406 -2) so we have a spare pole.

    Im not good at diagrams but here is an image. I thought to use terminals 7-8 for earth, 4-5 for battery and 1-2 for the momentary start.



    The backup battery switch is also a 4 pole 4TL1 - 3 - a Two position switch.



    We would use terminals 7-8 for earth, 10-11 for battery and wire the start power line through contacts 2-3 so in the "on" position the start power battery line is disabled , but the "start" momentary position of the start power switch is still enabled.

    Hope this does not confuse the situation but I think this arrangement gives effect to what Rotax say we need without compromising reliability.
      
    Report

  • Re: Momentary start power switch or not?

    by » 8 years ago

    Bill, please check this to see if I am on the right track.
    WiringEng4PDTstartswt.pdf (You do not have access to download this file.)
      
    Report

  • Re: Momentary start power switch or not?

    by » 8 years ago

    Great drawing! I think the wires to terminal 7 and terminal 5 need to be swapped.

    SP1-12 needs to go to #7 that connects X3 pins 2 & 3 and the battery.

    The grounds on 7 need to go to 5, that then connects the two grounds when the switch is actuated.

    If rotax say that start power switch connection between x3 pins 2 and 3 must not be made when using the backup battery then I think an extra pole will be needed on the backup power switch.
      
    Report

  • Re: Momentary start power switch or not?

    by » 8 years ago

    OFF, Center and UP (m) switch positions shown: have a look at all three pages
    Binder1.pdf (You do not have access to download this file.)
      
    Report

  • Re: Momentary start power switch or not?

    by » 8 years ago

    Rob, great diagram but FB2 -12 needs to connect to terminal 4 not terminal 8. SP12 - 12 N needs to connect to terminal 8 not terminal 4.

    The way it is now, when the switch is activated 12 volts is sent to the ecu ground via pin 4 instead of being connected to the airframe ground. FB pin 2 is grounded via pin 8 instead of being connected to FB pin 3 and 12 volts.
      
    Report
You do not have permissions to reply to this topic.
Related Topics
Title Category Replies
912iS EM Battery vs Start Power Switch 912iS Technical Questions 2
Hard Start of First Try 915iS Technical Questions 2
Start Power Switch 912iS Technical Questions 3
912 ULS Oil Pressure Switch 912 / 914 Technical Questions 11
"Oversquared" Powersettings 915iS Technical Questions 7
Follow Us

Recent Videos

Safety First!

 

To receive critical-to-safety information on your ROTAX Engine, please subscribe to
ROTAX-OWNER.COM

ROTALK News



ROTALK NEWS Episode 5
Rotax-powered Sling aircraft from The Aircraft Factory, the AVMAP Navigation and engine monitoring system, and the Rotax powered Tucano Experimental and Light-Sport Aircraft.



ROTALK NEWS Episode 4
ROTAX's 915iS-powered Aquila A211 test aircraft, the Scheibe SF-25C Falke (first-ever 912-equipped aircraft!) and ROTAX factory in Gunskirchen, Austria.


ROTALK NEWS Episode 3
Michael Smith's Rotax-Powered Searey Circumnavigation, the amazing Rotax-Powered Lockwood Aircam and Anthony Caere's chimpanzee rescue operations.

Prize Giveaway!


SUBSCRIBE NOW
to automatically enter this years draw!

Login