Starter motor relay

·         SUMTEK

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Hello doug, thanks for taking the time to man this forum...
I would like to know if there is any reports issue with the starter relays fitted to the jabiru aircraft? I own two Jabs, a j230 and a J 160. The starter relay on the 160 is con tangly playing up, I'm on my 4th one in about 3 years! The trouble started with an uncomanded engagement of the starter, disassembly revealed the internals were ver corroded, however I am now plagued with issues around the starter staying engaged post start, not all the time but every now and then.i have exchanged the starter for another but the issue keeps popping up, the only constant is the battery which needs a charge every now and then. The J160 has the night VFR panel if that helps. I'm getting to the point wherei just don't trust it!
Any help would be appreciated.

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·         Doug Smith

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G'day,
No problem, thanks to everyone putting up with my "occasionally" tardy replies.
Like any part we occasionally have issues with starter relays. Many of them need metal-metal contact to the firewall to provide the earth and corrosion or just dirt can build up there and cause issues... But poor connections resulting in difficult starting are far more common than uncommanded engagement.
If you saw corrosion inside one of the bad ones it might be a hint that water is getting in there, either if the aircraft is stored outside or when washed - it ican easily get into the cowl in front of the windscreen and run down the firewall.
Otherwise they're a relatively simple thing on a reasonably simple circuit so shouldn't really cause trouble... Depending on your aircraft the might be a starter engagement light connected in there but assuming that's been connected properly, that just goes from a terminal on the starter through to a light on the dash.
Do the uncommanded starts happen only when the master is on or Anytime?
Unfortunately there's no real "standard" issue with the relays and so no "standard" fix... uncommanded starts are a serious safety issue so I'd suggest you take it to a sparky or to jabiru and get someone to take a look at it. Checking pin-outs and resistance on all the circuits would be a good start, and going over all the connections for corrosion is always worth doing.
Hope that's of some use, let us know how you go.
Regards,
Doug.

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·         SUMTEK

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The uncomanded starter engagement relay had collapsed inside due corrosion with no external indications, unite scary when it happened! Definitely reiterated that the prop is always live. Every now and then the starter will stick on the light on the panel will stay lit and you can hear it running sometimes engaged with the flywheel and others just running, the only way to stop it is to get the cowl off and tap the relay. I believe that the relay is spring loaded to be open so I discounted an earth issue but wil look at the firewall earth pints all the same. Thanks