Basic description of Generator and Lane system operation

All my aircraft have momentary start ECU/switches so it is so there is no shutting off needed. However, I have added onto the checklist to turn the Emergency ECU switch on before starting so you have fuel pressure. Then turn it off after starting. I have found they start immediately not having to wait 2 to 3 seconds for fuel pressure to build while cranking the engine. Greater chance of leaving it on.......... 

Peter Avery wrote:

Paul.

We are running a number of 915is engines in our Magni gyros here in NZ.

Through practical testing I can confirm the following.

Gen A failure   both lane lights flash together. With Gen B now powering the engine management system

(EMS) & the battery backup switch turned on a small amount off charge will flow to the battery.

Battery voltage still reducing though , depending on loads.

If Gen A happened to come back on line & resume powering the EMS & Gen B the airframe & battery the lane lights continue to flash until engine shut down . Next start they would act normally.

Gen B failure- No flashing lights but a decline in battery voltage can be seen. Backup power switch on & again a small charge will come to the battery from Gen A.

If Gen B failed & the backup power switch is on & then Gen A failed you will again get both lane lights flashing until shut down. Battery is now powering EMS & airframe loads.

If starting with Gen B failed then the engine will stop when the start power switch turned on is turned off

unless the engine rpm is above 2400/2500 & the EMS is now being run by Gen A.

A bit of a double up with what Jeff has posted, but this is what I have found through failing each generator and operating at various rpm.

cheers

Pete Avery.

Peter, yes this does correlate with what Jeff got, and I also agree with in the Rotax Light warnings. Thanks for doing and providing results here. 

Just completed and revised my first attempt in the original post based on everyone's comments. I think it is accurate but again open to any input. I guess the only open item here is the dual generator failure when the battery connect switch is left on. It appears this is a situation but we want to know why. As Rotax Wizard proposed, he will try to find out when Rotax gets back after the holidays. Hopefully the answer will make us a little smarter. Again, great thanks for the effort here trying to get OUR best operations figured out for the success of Rotax.

Great thread. Exactly the type of information I like to have. One question, after reading through all of this, I see some posts referencing Generator A and B and some Referencing Alternator A and B. Some airplanes do have externals alternators (not mine) but We are talking here specifically about the Internal Generators A and B only, Correct?

We are talking about the internal generators only, and the terms generator and alternator are being used synonymously.  Probably my fault, I’m used to referring to a generator that produces an alternating current as an alternator. Rotax uses the term generator.