A320 Bus Ties and AC ESS ALTN p/b

[FlyHome]

Hi Guys,

Was just wondering if you could help me understand.

Firstly could you tell me what situation would demand that you manually select the AC ESS feed ALTN p/b? I understand that normally if there is a problem with AC BUS 1 it will automatically switch supply of the AC ESS BUS to AC BUS 2.

Secondly I was wondering the same of the BUS TIE p/b if you select it off. Again what situation would you choose to do that in?

Many thank for any answers.

Thank you
FH

[Field In Sight]

Not all aircraft auto transfer on failure of AC bus 1.
You press this button iaw with the ECAM checklist on older aircraft.

I did once (in the sim) have a simultaneous AC Bus 1 fault and SD failure.
No ECAM was shown, but if you looked on the overhead panel, the only amber fault light was on the ALTN FEED pb.

This was apparently to make the point that you can dispatch with an SD inop.

Fortunately all our aircraft, currently, have auto transfer.


Cheers.

[FlyHome]

Thanks for that was struggling to understand what its purpose was

[Flo121142]

The reason why Airbus decided to automate the transfer was a safety recommendation issued after an incident, in which the power to the AC ESS bus could not be restored with the AC ESS Feed P/B, resulting in, amongst other things, a total loss of communications...you can find the incident report here: http://www.aaib.gov.uk/cms_resources.cfm?file=/4-2009_G-EZAC.pdf