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"B" Ignition Fails in Flight

N

N223JH

Well Known Member
9 hours on #120264, soft start harness installed before initial start up in Oct. No engine anomalies heretofore.

Mag check normal, 40 minutes into local flight, OAT 60F, experienced slight "blip" momentarily 5 miles from field. Reduced power and got it again for a split second. Landed, checked mags at 2K rpm. With "A" switch off, engine stopped cold, came back without backfire. Tried at 3K. Dead again, shut down.

No visible damage or loose wires. Called Vans. Ken said call Rotax. No surprise here and he hadn't heard of any ignition failures execept wiring miscues prior to initial startup. Will start engine tomorrow to see if possibly heat-related problem.

In any event, I ain't flying this plane till we get some answers from Rotax. Am registered on US Rotax site.

Has anyone on the Forum except "Safety-related issue" thread experienced ignition failure...perhaps heard about another 912 crappin' out like this?

I'm hoping Rotax has a trouble-shooting procedure I can utilize; don't want to start aligator-clipping my way around an engine under warranty.

Jim N233TX
 
Is this a add on soft start module or the built in Rotax soft start modules?

If this is the add on module remove it and do a ground run up. If both modules are fine then the soft start add on module is bad. More than likely it failed due to excess heat (180F) where you located it.

If it is a Rotax module it is covered under warranty. You will have to buy a new one ($1,000) and submit a warranty reimbursement request and return it with the old part.

Hopefully, this is it, and not the switch panel going bad.

Let us know how it turns out.
 
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Soft start,,,really?

Larry, this was the little harness Vans sent me back last summer...hook up some pin connectors from firewall to that spiderweb on top. Wasn't a "module" as such. Is there a history of this wiring going down due to heat? I routed the wiring eggs-ackly per instructions.

I'll be speaking to Rotax ASAP tomorrow and will keep y'all posted.

Jim
 
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Others have Failed!

One of Pete's Failed. Here is the link.

http://www.vansairforce.com/community/showthread.php?t=55586

Send him a mess and he can tell you how to test the coil to see if its bad. He does not have the soft start. If you have a yellow sticker on your IGNITION MODULE that means its a soft star. You can see a picture of one at this link page 2, figure 2, left hand side of page
.
http://www.vansaircraft.com/pdf/revisions/RV-12/Section_46.pdf

Also check that your ground on your ignition module is clean. Its on a 3/8 bolt in front of the right carb on top
 
Have you disconnected the ignition wire coming from the switch panel going to the ignition module and checked it with an ohmmeter? Think you should have continuity to ground (zero ohms) with the ignition switch OFF and no continuity to ground with the ignition switch ON. Simple check to see if your problem is in the switch panel or the module. Could also be a connector between the switch and the ignition module.
 
Marty, I don't have the build manual here at the house; where is best place to disconnect? Where it connects fwd of firewall or somewhere closer to the panel switch? This is good info on the RV12 system 'cause I expect Rotax Tech will only be able to address FWF troubleshooting.

Jim
 
Common failure area

One area to check is the two red wires near the ignition modules. From memory they are quite short with spade plugs on the ends and connect to the wires in the shielded braid.

They have a habit of breaking inside the plastic shielding caused I suspect by the fact they bend around to plug into the wires in the shielded braiding. Unplug them one at a time and hold onto the plug and the wire as far down as you can and pull and if it is broken the covering will stretch. They mostly break near the spade plugs so just cut off and install a new plug.

Have seen this several times and ignition fails just as you said.

Hope that helps :)
 
Ignition test

On page 46-12, figure 2 is a picture of the ignition connector. Separating the two halves of that connector will help to determine if an ignition problem is forward or aft of that connector. With that connector apart, the engine should start and run regardless of the ignition switch position.
Connect a test wire to the airframe (electrical ground).
Start the engine.
Touch the pins in the engine side of the connector, one at a time, with the grounded wire. If the engine stops while touching a pin, that means that the OTHER pin connects to the faulty ignition. If the engine does not stop when either pin is touched, then the problem is aft of the connector.
Remember that with the ignition connector apart, the ignition switches will not stop the engine. It will be necessary to ground both pins on the ignition side of the connector or shut off the fuel.
Touching a bare ignition wire while the engine is running could result in an electrical shock.
Caveat: The above is theory. I have not actually tried performing this test. The results of this test might not be significant if there is an intermittent problem that does not exist during the test.
Joe
 
Bad "B" Module

That's the verdict of Bret at LEAF, based on a couple hours of long-distance trouble-shooting. First we eliminated the panel switch, then the parts down on the generator. Supposedly these modules don't fail often, especially after only 9 hours TT.

I didn't press him on the issue, just asked that he bench-test both my modules and send back two good ones. Rotax policy prohibits simultaneous shipping so I'll be waiting on the round trip to the North Woods before I can reinstall. Oh well, it's January.

Jim
 
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