What happens if you turn off the master with the engine running?

Only the battery connection is controlled with the master switch. X3 Pin3 from the Rotax supplies power to electronics, regardless of whether the battery (master) is connected or not.

If you want to kill power to all devices when you smell burning, you need to use your avionics and other bus switches, breakers.

Jason Fish wrote:

Only the battery connection is controlled with the master switch. X3 Pin3 from the Rotax supplies power to electronics, regardless of whether the battery (master) is connected or not.

If you want to kill power to all devices when you smell burning, you need to use your avionics and other bus switches, breakers.

Wow. So if you smell burning, turning off the Master will effectively do nothing and you must manually pull all of the circuit breakers?

The avionics switch should suffice in many planes. But if you have multiple circuits, each with an independent switch or breaker, then yes. But only you know how your plane is wired, which circuits exist, whether those circuits are equal to, or children of, the main switch, which breakers do what, etc. Everything in the green box is up to the builder/manufacturer, and should be in the POH.

Jason Fish wrote:

The avionics switch should suffice in many planes. But if you have multiple circuits, each with an independent switch or breaker, then yes. But only you know how your plane is wired, which circuits exist, whether those circuits are equal to, or children of, the main switch, which breakers do what, etc. Everything in the green box is up to the builder/manufacturer, and should be in the POH.

Actually, no one knows how my plane is wired because it’s a Tecnam and Tecnam’s are notorious for poor electrical and poor documentation. Even an A&P IA who is an electrical genius is baffled by some of the wiring decisions he saw Tecnam make on my airplane. The POH is full of lies, which includes the wiring diagram. So it’s really a mystery to everyone how it’s wired. ?

And following wires to see where they go is nearly impossible because (unlike most airplanes where have color coded wiring) they’re all white wires and all bundled in together with 20+ other wires.

Hi all

OK I am no electrical expert however can answer a few of the many questions that came up on the iS wire system.  Indeed anything on the airframe side is the OEM, like Tecnam, who make the airframe harness.  The Rotax harness is white because it is tefzel wire, a teflon wire coating that is highly resistant to heat and required by many authorities as it will not melt or burn until very high temperatures (150C or 300F in most cases)  In the event of a fire you do not want poisonous fumes in the cockpit.  As for where does the energy go when the B side generator stops feeding the aircraft wiring.  Simply speaking it is directed to ground by the shunt type regulators on the side of the fuse box.  

Cheers