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Rotax Soft Start


S3flyer

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I'm jumping the gun a bit but my plane is having trouble starting and it is possible that one or both of the ignition modules have gone bad.  I've got a mechanic coming out tomorrow to go through the litany of possibilities from plugs to carb to throttle cables to air filters to whatever.  Hopefully, its something simple but.....

 

Ignition modules are approximately $1K each (ouch!) and I've heard that the Rotax soft start kit includes replacements for both modules for quite a bit less.  Lockwood has: http://www.lockwood.aero/p-3710-advanced-soft-start-start-module-kit.aspx which includes two modules for about $950.  Is this the right kit or is there another part number?

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That's the one. Before you go crazy try this very simple test. No work involved. Try a start if it won't start, then stop right there. Place an ice bag around the modules for 20-30 minutes  to cool them down. If it starts buy the new soft start models. If this doesn't work then look at the 6 pin connectors up by the ignition models for broken or abraded wires. Especially the red ones.

 

Tony is right. Make sure the battery is turning the prop fast enough. Jump it if need be to make sure you have enough juice. If you are just a tad slow, which you wouldn't be able to detect, it would not start.

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Confirm battery has the 'horse power', not just voltage showing.

I have the soft-start; but if the battery delivery reduces output, it also will have starting problems.

FYI -- I'm aware of three CTsw units (late '06) that have had module failure. Two with one module, the other with both.

I believe the failed units have been forwarded to Lockwood for their review, etc...

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Interestingly, I just got back from the airport.

 

Had a BFR (for me) scheduled for tomorrow, and I just wanted to check the fuel and make sure the plane would start.

 

It wouldn't. Crank and crank and crank. Choke and no choke. No throttle and full throttle. Suspected flooding so fuel valve off, full throttle, crank and crank and crank - not so much as a sputter. Pulled 2 plugs. Top was dry, bottom only a tad damp.

 

On the bright side, my Aerovolz lithium iron battery spun the engine with authority throughout. When I was done, I stuck it on a battery tender which showed "Full Charge". I checked it and it's still at 12.99v after all that cranking.

 

I do have the BullyHawk module.

 

In any case, I'll try again in the morning and ket you guys know what happens.

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Mine is a 2007.

 

It was not especially hot yesterday - maybe 75°, and will be cooler this morning when I try again.

 

I'll take some ice along, and if it doesn't start, I'll give that a try.

 

Am I correct that there are two ignition modules stock, but they can both fail simultaneously in this manner?

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Eddie -- hope you had better luck than me.  All tests pointed to bad ignition modules :( so I put in an order a CPS for part number 881 280 (Advanced Soft Start Module) for, gulp, $995 (or one aviation unit  :D ).  They are back ordered and due on on the 18th.  3 of the 6 are already claimed.

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They are a 6 pin plug and play except for two easy to install wires. On each module a corner wire is left out. You will add this wire to each module and run them down to the starter solenoid. You will pull off the middle small bottom wire on the solenoid between the two wires of larger size coming and going off each side. Cut the electrical connector off and now join your two new wires from the modules to this wire with a new connector. When the key is turned this will energize the soft start feature in each module.

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FWIW, both of mine failed in hot weather but would run fine when it was below 60F or so.  The ice trick never worked though I tried it multiple times.  I bit the bullet and bought new modules, the ones that run in "soft start" mode for 5 seconds or so.  The engine runs fairly rough until the 5 seconds are up.  How that is better for the engine is beyond me.

Late 2006 build, BTW.  First failulre in 2009, replaced in 2011.

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On the bright side, my Aerovolz lithium iron battery spun the engine with authority throughout. When I was done, I stuck it on a battery tender which showed "Full Charge". I checked it and it's still at 12.99v after all that cranking.

NB, with LiFePO4 batteries, 12.99V unloaded corresponds to 30% state of charge. Your tender is calibrated for Pb for which 12.8V or above is 100% SOC
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