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WWhunter
09-23-2011, 05:30 AM
I was doing my run-up today to go flying. The engine seemed to be running rough and sure enough when I did the mag check, the motor quit on one of the mags. It was completely dead. The builder put in two toggle switches to check the mags and I swapped the leads so I know it wasn't the toggle switch. During mag check switch #1 allowed the engine to run while switch #2 did nothing. Engine was only running on mag #1.

I swapped the 4-pin plugs on the Elctronic modules and then it worked on switch #2 but not on #1 so I am figuring the module is bad.
Is there any way to check this module? Sort of sucks since I was hoping to fly to a couple of flyins this weekend.
Oh, the motor only has 150 hrs. TT

Does anyone have an idea where I can get a replacement for less than giving up my first born? The price for a new one is utterly rediculous!!! There is no reason what-so-ever for it to be priced close to $1,000!!!!! Pure greed from Rotax. I am starting to hate this engine already after flying for 25 years behind Lycs. and Cont. that just keep chugging along. Okay, I'll get off my rant.

Thank you,
Keith

jtpitkin06
09-23-2011, 07:11 AM
Carefully inspect the wires between the four pin plug and the module. There have been cases where the wires have broken inside the insulation due to vibration and mounting. You may be able to feel a break in the wires. If you don’t feel anything try using an ohmmeter and a needle probe to check continuity on each of the wires between the connector and the module.
If that doesn’t reveal anything, you’re probably in for a new module as you have done all of the swapping to isolate the problem.
Scour the internet for the best price. I saw a few listed at about $850.
Good luck.
John Pitkin

sdemeyer
09-23-2011, 08:07 AM
I would also double check the wiring. I have had broken wires several times. In my case, the wires always broke somewhere between the module and plug. Many builders have moved the modules up by the firewall to eliminate this problem, caused by vibration.

DesertFox4
09-23-2011, 09:44 AM
Keith, odds are it is a broken wire as stated already. The electronic modules are always suspected first until further investigation reveals the copper strands inside a wire have failed from vibration but no break is visible as the insulation is still intact. Usually it is the ground wire so try that one first. As John said finding the break is pretty simple with the continuity tester hooked to two stick pins. Carefully push one pin through the insulation very close to the module as possible in case the break is right were the wire comes out of the ignition module. The other pin you will gradually work down the wire until you lose continuity. Wiggle the wire as you go to simulate the vibrations of the engine in case it has continuity at rest but loses it when the engine is running. Odds are after a short time you will find the break. Splice in a new section of wire and you are good for the weekend fly ins.
Obviously that repairs the broken wire but does not change the conditions that caused the failure. Think about moving the ignition pack to the firewall side of the engine mount if wiring and space allows. This isolates them from the engine vibrations. Make sure your wires are secure and not flopping around and causing fatigue to the copper strands. This seems to eliminate the problem and you should have years of reliable flying. Do not order an expensive module until you've tried this method.
Good luck and please report back what you discover.

WWhunter
09-23-2011, 01:40 PM
Guys Thanks for all the help. I located the problem. Last night I had read that there was a service bulletin about broken wires and had looked last night but it got dark on me before I found anything. Today I dove into it headfirst!!! I did all the diagnosing that I could think of and finally figured out which wire I had an issue with. The red wires that go to the electronic module. It ended up being broken (albeit nearly undetectible) right inside the connector. It looks like it had been crimped on the internal wire but the crimp that is supposed to be done on the wire casing was not done allowing the wire to break. After fixing that one I also found that the other lead was broken where they exited the woven shielding. This was not a complete break but barely held together so it was just a mater of time before it broke the rest of the way.
Thanks again,
Keith

HighWing
09-24-2011, 06:44 AM
The broken wire thing was being talked about since the get-go on the 912. I am attaching a picture of my engine and will try to describe what I did to protect the wires. first I formed out of sheet aluminum a "C" section that I could attach to the modules with wire ties - I used three. To that I riveted an aluminum chanel that rand aft to the sheilded portion of the bundle. All the exiting wires were tied very tightly to the channel. I flew with several guys that had broken wires on occasion, but was able to put 900 hours with this mod with no ignition issues - unless you count the broken supports - twice. I guess I isolated the vibration from the wires and transferred it to the mount stand offs. The engine mount mounting is ultimately the way to go. That modification will require some lengthening of some of the ignition wires. My wires were in good condition, so I moved them around where they fit and bought what I needed for the two longer runs.

A note to those that might want to go that way - the wires simply unscrew from the modules and the spark plug ends. I also found that the rubber tube abrasion protection can be removed and reused. It is glued to the wires, but if you stretch and bend, the glue can eventually be broken and they will slip off.

dholly
09-25-2011, 11:19 AM
I found a broken adel clamp on the module mount during a pre-purchase inspection of my 912ul @ ~170hrs. The ground wire SB was done and wires bundled tightly and well secured but I'll be keeping close eye on this.