CAN fault after cold start

[Dejw]

Hi,

I have Rotax 912iS installed and when I press and hold the Start Power Switch, then Start Switch and if I let go the Start Power Switch in first 10-15 seconds after the start, I get CAN Fault message, both Rotax warning lights (line A and B) are solid and all avionics is running on battery.

If I hold the Start Power Switch longer than 10-15s then everything is fine. Also if I turn off the engine and start again, everything is fine.

The engine runs without no problem in all cases.

Any idea what might be wrong?

 

[porterjames]

May not be anything wrong. Has this been different than past experience with the same airplane? If so, what was done (changed or repaired) prior to this new behavior?
Otherwise, if you are new to this airplane, just keep the power switch engaged 10-15 seconds after start, as long as everything works and the engine behaves normally.
You mention that "all avionics is running on battery"? Is the engine alternator failed? Obviously one runs only the engine (this one is functioning since the engine is running) the other alternator runs the other equipment- avionics.

 

[PaulSS]

Try setting 2500 RPM for 5 secs after start before you release the start power switch. This will get Gen A on line and might solve your problem. I have a start power timed relay, so never get this problem because the relay stays closed for about 30 seconds in total, thereby powering the start circuit.