Originally Posted by
Hot and Hi
Somewhere else here within the RH Forum, the consequences are discussed of a total electrical failure in case of a Robinson piston product (
Hypothetical - Robinson Total Electrical Failure). As Robbie pilots know, if after an alternator failure one continues to fly until the battery is flat, the donkey would continue to run, but one would lose all electrically driven instruments incl the RRPM tach.
However, if for example in case of an electrical fire one elected to switch off both ALT and Master, the tach's would still be energised via a special circuit straight from the battery.
How does this work in a Cabri?
Obviously the glass display (EPM) will no longer work if both the master & alternator are switched off / failed. The backup Nr indication system (BARC = "Boîtier Alarme Rotor et Carburant" or "Rotor and Fuel Alarm System") is run off a direct-to-battery connection.
The BARC system always provides backup power to a set of three lights (indicating Low Nr / Nominal Nr / High Nr range) and a separate "Low Fuel light" which is triggered by an independent float measurement system once there's about 14-16 litres in the tank left. The BARC also powers the "horn" which gives audio warnings at excessively high or low Nr.
I've attached the relevant pages from the RFM in case I've butchered the verbal explanation.