It is not likely you will have the engine quit because of a dynamo failure. The Rotax 912 has three separate electrical generating systems. Two for ignition and one for the dynamo. The dynamo can fail and the ignitions will continue to operate.

The internal dynamo is rated at 18 amps maximum and 14 amps continuous. If you put too much load on the dynamo it can overheat and burn out the stator coil. Just to be sure you are not overloading the dynamo, add up the amps of all the electrical items. The radio, lights, instruments, sirens, etc. Make sure they do no total over 14.

The regulator is a combination rectifier and regulator. the dynamo puts out AC current, the rectifier changes the output to DC and the regulator limits the voltage to 14 volts.

The only failures you can get are:
Failure of the stator coil. Charging system will not work at all.
Failure of the regulator. Charging system will show over volt or under voltage or complete failure.
Failure of the rectifier. Wild AC current into DC system. Possible noise in audio system. Voltage appears normal or low. Fault can not be detected with a simple voltmeter. Can damage electrical components like radios.

The rectifier portion is made of 4 diodes. One or even two diodes could fail and you will still get reduced charging but it could induce noise into the electrical system.

It is still worth your while to have the electrical system checked with an oscilloscope; particularly your rectifier/ regulator. Your engine will not quit, but you could damage some other items.

Let us know what you find.

John