Total Electrical Failure
 

Somewhere else here within the RH Forum, the consequences are discussed of a total electrical failure in case of a Robinson piston product (https://www.pprune.org/rotorheads/62...rnator+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?

Kinda the same, you flick the rpm warning backup switch on and that is direct from the battery. Not very granular, just tells you green or too high or too low rpm. It is good enough with the correlator to get you down safely while the fire rages.

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.

A separate dedicated backup battery? Well I never knew that! Where is that shown on the wiring diagram and do you know where the backup battery is within the airframe? I can only think it would be in the console, is that right?

Ah damn it - now I look like a tool! I misread the "can be switched to a direct battery backup supply" as "can be switched to a backup battery supply". I believe you're correct in saying there is no second battery. I've corrected it now.

LMAO, it isn’t exactly clear in the wording and that had me doubting everything I knew about the BARC to the point of thinking, where the hell is this battery then as I’ve not spotted it in any walkarounds/preflights! Openness to learn a new thing overriding what I knew to be false 😄.

I suspect people do not get much practise with no EPM display and no governor, one or the other, but probably not simultaneously.

So much of a muchness then.

Can you confirm that - in case of a total electric failure and flat battery - the donk continues running? Just on the 1 set of magnetos, or will the electronic ignition (“plasma system ignition”) equally continue to work without supply of electric power?

The plasma is direct to the battery too, so the donk will continue to run on both ignition systems while the battery has the capacity to fulfil. Once flat, it will as you say rely on the magneto only. I would hope though in most scenarios the heli would be safely on the ground in the event of an electrical outage before the battery is flat.

I mentioned earlier in the thread experiencing a "short" in the primary electrical feed to the cabin from the generator.
Granted, it was intermittent and we were still preparing to taxi prior to flight so not so serious.

All electronic systems lost. Engine grumbled and ran rough for an instant as the fadec was lost but the revs stabilised while in the hover.
Still enough power to put it back down while we tried to figure out what had happened.
It kicked in when collective was being raised and a minor vibration kicked in.
Felt similar to the drop when plasma is turned off during pre-flight.

Yeah the reason they use one magneto and one EIS, and not two EIS, is so the engine can continue to run without electrical power due to the magneto. Otherwise power loss would mean engine loss.

For those wondering, Guimbal states that the plasma will take >10 hours to drain the battery if the master were to be switched off.

Yeah, I was wondering. Thanks for making this clear. Now in an ALT failure you do *not* switch off Master. The emergency procedure in a Robinson piston is to leave Master on, but switch off non-essential electrical consumers (lights, strobe, second radio, TPX, air con, RA).

The (non-documented) time the battery will last in this scenario is between 15 and 60 min before total electric failure, with an estimated median of 30 to 40 min. Not sure what drains the battery most, but essential consumers would include the gyro instruments, avionics fan, the remaining radio, any glass instruments and the panel-mounted EFB... Can't think of much else.

Would be the same in a Cabri, not? Only difference I can see is that from the point of total electrical failure in a Cabri you only run in one sets magnetos, so no more redundant ignition.

What is the plasma?

It is the name of the electronic ignition system.

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The Cabri G2 is now certified in Russia. :ok:

We'll see at last funny videos with the G2. :}
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Hope they have their dash cam.

Hi Guys,
Can anyone give me a contact of how to find out a definitive list of which FTOs operate the Cabri in the UK please?
I already have 35 hours and need to finish off the course after a long Covid break.
Many thanks.

I think that Heligroup are the UK agents for Cabri: https://www.heligroup.com/cabri2/

Maybe if you emailed them they could provide you with a comprehensive list of all of the Cabri operators in the country?

Cabri are to be seen in Fairoaks, Goodwood and Lee-on-Solent, but that might not be of any help if you are North East based!

Many thanks.