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RPM LOST ON IGNITION CHECK

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1 week 2 days ago #19183 by Navtrack
RPM LOST ON IGNITION CHECK was created by Navtrack
Hello,

While making the check of the ignition on the number 1 (A module), I have a 800 RPM lost only when the engine has been stopped after a flight or the aircraft has been parked outside in a sunny day therefore resulting within the engine cowl a hot ambient temperature. It's working well at the first flight of the day when I get out the aircraft from the hangar !

I have change the DUCATI Electronic Module with no result. I have change the ignition coils on the ignitor circuit A with no result. Does anybody has an idea what to do to solve my problem ?

Best regards,

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1 week 2 days ago - 1 week 2 days ago #19185 by Roger Lee
Replied by Roger Lee on topic RPM LOST ON IGNITION CHECK
"I have change the DUCATI Electronic Module"

It is not a Ducati. Did you put in a Rotax ignition module?
Since changing the module didn't help:
You most likely didn't have a real ignition module problem, but only a bad wire. Check the red wire on top of the engine to the modules, Really do a good check on the wires into the 6 pin connectors for breakage at the pin inside the plastic connector.
Did you try swapping the modules at the 6 pin connectors and see if the problem stayed the same or changed? You can ohm out some of these wires to their sources, but do these simple checks first. Most problems aren't exotic, but simple fixes. Start there first.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell
Last edit: 1 week 2 days ago by Roger Lee.

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1 week 2 days ago #19186 by Navtrack
Replied by Navtrack on topic RPM LOST ON IGNITION CHECK
Hello Roger,

Thank you for your prompt reply. The modules on my ROTAX 912ULS, mounted on my CTLS, are the original's one made by DUCATI.

At the begining, I swapped the pin connectors and had the problem on the other module. That's why I incriminated and changed it.

I will have a look on the wire and keep inform you about the result.

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1 week 2 days ago #19187 by Roger Lee
Replied by Roger Lee on topic RPM LOST ON IGNITION CHECK
These aren't Ducati modules.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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1 week 1 day ago #19189 by Navtrack
Replied by Navtrack on topic RPM LOST ON IGNITION CHECK
Please, visit the following web site to see what is installed on my engine.

www.carmo.nl/index.php?main_page=index&c...711_4618&language=en

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1 week 1 day ago #19193 by Kevin Stewart
Replied by Kevin Stewart on topic RPM LOST ON IGNITION CHECK
My ignition modules have Ducati embossed on the outside of the cases :-) They may not be made by Ducati but they certainly have their name on them.
I've just had 2 modules fixed by Carmo, their service was excellent and quick. One had a faulty kill input, the other wouldn't fire at cranking speeds when cold. Both are known faults with these modules. You've only got to speak to the guys at Carmo to see how common it is.

Test results:
1. You have an 800rpm drop when you switch off module A when the engine is hot.
2. If you swap both of the connectors then the fault moves to the other module.
3. Replacing module A does not fix the fault.

Conclusions:
1. If switching off module A results in a large rpm drop then the module B circuit/module must be at fault.
2. If swapping the connectors moved the fault to the other circuit (ie. switching off B circuit results in 800 rpm drop) then fault is in B circuit not module.

The ignition circuit consists of:
1. Trigger coils. (cannot cause observed symptoms)
2. Charging coil.
3. Coils.
4. HT leads & resistive caps. (cannot cause observed symptoms)
5. Spark plugs. (cannot cause observed symptoms)
6. Earth connections to manifold.

Given that you have already changed the coils then I would look at the charging coil and the earth connections. You could use a voltmeter to measure the charging voltage on the red wire to each module, they should be about the same. I have some oscilloscope traces which look like they would give you about 50-100V AC at 3000rpm.

Another thought is that you could measure the resistance of the charging coils with the ignition modules disconnected and heat them up with a hair dryer to see if one changes more than the other. Good luck!

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1 week 1 day ago #19196 by Roger Lee
Replied by Roger Lee on topic RPM LOST ON IGNITION CHECK
Hi Kevin,
"My ignition modules have Ducati embossed on the outside of the cases"

How old is your engine?

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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1 week 19 hours ago #19201 by Navtrack
Replied by Navtrack on topic RPM LOST ON IGNITION CHECK
Roger, It's the new model, 2009.

Kevin, following is what I have done :
Ignition key on # 1 (module A) =800 RPM drop. Ignition key on # 2 (module B) = Ok
I swapped the connectors at the modules :
Ignition key on # 1 = OK, ignition key on # 2 = 800 RPM drop.

Refer to what you said, I understood that the problem is the circuit and not the module ! Would you please confirm ?

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1 week 17 hours ago #19202 by Kevin Stewart
Replied by Kevin Stewart on topic RPM LOST ON IGNITION CHECK
In answer to Roger, it is a 2003 912UL with the 4 pin plug and bullet connectors.

I don't have a key switch ignition in my aircraft, I have 2 separate switches so I cannot tell you which circuit is on in which key position. You can easily measure the kill wire connection resistance to ground whilst operating the key. The heavy maintenance manual has a wiring diagram.

From what you have just written then yes, I would agree that the fault lies in the wiring or engine side components and not the module.

Kevin

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1 week 12 hours ago #19205 by Roger Lee
Replied by Roger Lee on topic RPM LOST ON IGNITION CHECK
Old ignition modules cases used to have Ducati embossed on them, but different internals were from Rotax. Now they don't have Ducati embossed on them any more.
Your problem is before the modules. Check the wires feeding into the pin connectors, ohm these wires from the back of the engine out.


Diagnostics. Heavy Maint. Manual. Section 74-00-00 page 22
3.12) Measurement values for the ignition unit
The following measurement values can be checked at the appropriate point after
detaching the plug connections.
Generator coil
(on stator) yellow - yellow 0.1 to 0.8 Ω
Generator coil yellow - ground ∞
Charging coil (on stator) red - ground 3.2 to 4.5 Ω
Trigger coil green/white - blue/yellow 115.0 to 123.0 Ω
Trigger coil new *
(with clamps) white/yellow - blue/yellow 220.0 to 250.0 Ω
Primary ignition coil connection contact - ground 0.1 to 0.4 Ω
Secondary ignition coil high voltage - High v. 6.1 to 6.7 kΩ
Spark plug connector 4.4 to 6.0 kΩ

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell
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1 week 12 hours ago #19208 by Navtrack
Replied by Navtrack on topic RPM LOST ON IGNITION CHECK
Thank you Roger, I keep you inform with the result.

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