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912 ignition modules

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How to jump start ?     I suspect, or rather I am convinced  my battery life is over as I do not get enough of a crank spin to start the engine.  (battery has been fully charged).  I attached jumper cables to my car and got a bit faster crank but still very slow and not enough to start.   Even with cables attached it acts like the battery is too weak.    I do not intend to fly with this weak or dead battery however I am curious why I can't get the start even with jumpers.    My only thought is, does the jumper cable lose current from the car side to the aircraft side resulting in very little electrical current provided to the weak battery?   (am using regular jumper cables you buy at the car shop)

note battery is a odyssey pc310 - sadly this is only 2 years old

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Jumper cables don't get good connections. If you notice, the connection points get hot when cranking. They just don't have enough contact area.

I also don't recommend jump starting if you can avoid it. Batteries have a safe charge rate, and they can charge significantly faster than that.

A fully charged battery doesn't mean its condition is good enough to crank; if it's degraded, it can't deliver the power needed in both voltage and amperage. You either need to CCA test the battery, swap it out, or get a better connection than jumper cables.

Continuing to try and crank the engine without sufficient voltage will damage your starter.

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Update.   I made a temporary connection to a slightly larger battery (than the PC310) and it starts perfectly.

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On 11/26/2017 at 8:31 PM, Tom Baker said:

You can run a soft start module with a non soft start, but the soft start functionneeds to be disabled. 

 

If you had individual mag(ignition)switches instead of rotary, I understand you could start on just the soft start and then switch the second one on.  Correct or no?

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No if you're using the Rotax soft start modules. They both have soft start in them and the engine starts better on both mags. That's why some have issues starting when one mag starting circuit drops out. One mag is never as good as both with 8 plugs firing on every stroke. That's one thing unique about the Rotax. The modules don't just fire on a compression and firing order they fire every stroke.

 

Yes if you had an old Bullyhawk add on to a module.

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I have an early 912 uls with 180 hours. Runs great. Has 2 green non soft start modules. Has had a little kickback but not since I got a new battery.

My understanding of choices:

1 Leave it alone

2. buy 2 soft start modules for 2k

3. Go experimental. Buy one soft start module and  Change to 2 mag switches and a starter key or button. Start on one soft start module and then switch the second on. 

 

 

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An engine kicking (meaning, the engine seems to stop rotating for a moment) is often a symptom of a failed sprag clutch, if it's not a weak battery.

If your engine kicks, STOP. Replace the battery and see if it happens again.

Replacing the sprag is expensive. Continuing to operate with a kicking engine WILL BREAK IT.

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It may or may not be the battery. What year is your engine?

Kickback should be stopped ASAP. As Corey said it will destroy your sprag and it's  expensive and a PITA to replace. The back part of the engine has to come off..

If you have a black colored starter replace it with the gold colored starter. Night and day.

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most likely the kickback is caused by your gearbox clutch not being tight enough. It is set by shim washers and is not hard to do with a press. Set it on the high side of the range and all should be ok. Use the Rotax manual for the procedure and figures. The tension should be checked at every 100 hr. service, I use a spring pull scale on the prop to check.

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Low gearbox friction should not have happened overnight and should have shown a trend over time in a diminishing friction torque. It should have been documented at each inspection in the logbook and if someone failed at either doing this check or putting it in the logbook then they did the owner no favors.

 

I would still like to know what year the engine is so to determine what starter it has, does it have a choke system or primer and how old is the battery? Hard starting may also indicate one of his ignition modules  has a failed starting circuit. When was the last carb sync?

 

Without knowing some of these variables anything is just speculation and may be throwing good money at the wrong part.

 

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Roger I agree 100% but have seen many times that the friction torque  is not even checked or documented. You would have to agree that low friction torque is very often the main cause of kickback on start up, especially with a weak battery or starter.

I guess what I am saying is that I would start with that first because it must be set correctly, otherwise even with a new battery and heavy duty starter it will still kick back and risk destroying the sprag. 

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Time out guys. 

Here is the central question I was trying to ask.  If one has a 912 uls that has old style ignition modules (non soft start)  and it is starting fine should one upgrade to  soft start module ?  (essentially 2 k dollars). 

It has a new battery and is starting very easily and well. (The previous battery was  old and it did kickback a couple of times when it was cold)

It is in inspection now and I can get friction torque measurement soon.

 

On 11/26/2017 at 8:31 PM, Tom Baker said:

 

 

 

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Getting the advanced start helps. You need the flywheel for the full effect too.

But it's not necessary. It's one of those things that is really expensive and not a lot to gain unless you're flying the pants off it in lots of short hops.

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If the modules are working leave them alone because if you swap to the new soft start you only get part of their function. You would need the flywheel too at $750 plus labor. So the entire swap for the soft start system is over $3K. There are thousands of 912UL's and ULS's out there with the standard modules.

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I'm one of the ones that has had issues of needing to "warm up" my ignition modules.  This only happens in the summer time, and only if the airplane sits for 5 days or more.  In those conditions the airplane would crank very strongly, but never quite start.  After trying for a long time it would finally catch and then work fine until it sat again for several days.

I was confused and curious about it, and was talking to my A&P.  He suggested that perhaps there was a small amount of moisture trapped in the modules, and when they sit for a while in the warm, humid Georgia summer conditions, the moisture could condense inside the units and keep the module from providing good spark.  Once the modules warm up a little, the moisture evaporates and the modules start working normally.  The next time I had this problem, I hit the module with a hair dryer for about 5 minutes and it fired up instantly, not even a full revolution.  

So the above is my current working theory, but the fact remains that occasionally if my airplane sits for a week in warm weather it will take either a lot of cranking or a blast of heat on the ignition modules to get it going.  It has never failed to start entirely (though if I had a weak battery and no available heat source, I could see running out of cranking time before it started).  Also, it's ONLY the first start of the day, once it's started once it fires instantly again for days unless the airplane sits a few days.

It's more an occasional inconvenience than a problem now that I know the workaround.  I started carrying a hair dryer in the airplane when making overnight trips just in case, but so far haven't needed it.

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Andy,

The heat gun is similar to using the ice. You're just tricking the module. If you still have a starting issue send the modules to Lockwood to be tested.

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Thanks Roger.  My understanding is that if the modules were bad I would not have this problem only once in a blue moon on cold starts, but on most hot starts.  Isn’t that true?

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Andy, my experience with temps affecting modules goes way back to the Ford modules when they first came out.  The potting material in these had a different expansion rate than the components and it would pull connections apart when it got hot.  The solution was to stand on the bumper and pee on the module :embarrassed-1030: Or, just sit long enough to let it naturally cool and then run with the hood on safety latch to get air to the module.  FWIW, I suspect that your modules may suffer broken connections when they are cool and when you apply heat, this rejoins these.  Not a very robust situation but I do understand why you are reluctant to bite the bullet and spend $2,000 for new modules.

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Anybody have an approximate cost and turnaround time for having the modules tested at Lockwood?  Because it’s Lockwood I’m guessing it’s not cheap.

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I replaced mine while they were still affordable but I don't know what I did with the old still good ones.  Maybe I can find them and sell them to Andy? ;)

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