Rotax 912 Voltage Regulator Problems

[Z-MRP]

Morning All, could the brains trust please assist me with some info re regulator failures on the 912 . We have two aircraft here, both Cheetahs, and between the 2 of them they have blown 9 regulators. 7 on the one and 2 on the other. What could be the problem Other aircraft fitted with 912 are having no problems

Z-MRP

[Morph]

I too have lost a regulator within the first 50 hours including a battery, cooked from being charged at 18 volts

The new one is now 70 hours old, and seems to be fine for now. Be interesting to see if there is indeed perhaps an installation issue to look out for etc,

What I did do in the meantime is seriously beef up the earthing of the motor and the power etc by installing heavy duty cables. My regulator sits against the firewall and the motor and charging circuit is isolated via rubber engine mounts. So all the power feed is via cables, on both the positive and the earthed negative. I am using heavy duty mutistrand battery cables, used by the 4X4 guys when they install the second battery. The copper component is about 6mm thick. I also kept all distances to a minimum. the longest piece of cable is about 200mm,

Is the regulator wired correctly?, see diagram

[Z-MRP]

Thanks Morph I will forward this info onto the guys at the club
z-mrp

[Z-MRP]

Sorry didnt see your question re is the regulator wired correctly. This is also a possibility but the wiring is as per how it was from the guys who make the Cheetah, but I will check against your diagram to confirm this.

[Stephan van Tonder]

Make sure first of all that ALL your earth wires are decent earths and that the regulator also has an earth. We had charging issues and was all sorted by putting some decent earths Engine to frame and battery and reglator to frame. Seems to be a bit of a shortcoming on the cheetah.