Electrical failure and RA

[Check_Airman 3]

Hi,On my last flight, I got the following level 1 alerts in the cruise:AC TIE 3 OFFBUS AC 3 OFFAfter consulting the manual, I noticed that both RA's displayed amber X's, indicating a failure.Questions:What are the power sources for the RA's? I could find this anywhere, and I find it a little strange that they would have the same power source. Is this just a Microsoft limitation?I also noticed that although the RA's had amber X's descending trough 2500ft AGL, the indicator appeared as normal behind the X, and all RA callouts occurred normally. Can this be fixed?I was also expecting to see NO AUTOLAND displayed on the consequences page since the RA had indicated a failure, but it never appeared. The retard mode of the AT worked as normal for the landing. Is this a bug? How would the aircraft know when to enter RETARD and FLARE modes? Does it use BARO ALT in the event of RA failure?Paul

[graysuit 0]

Hi Check Airman, I'm very interested about failure simulation. How did you get this failure? Did you set it in PMDG failure menu, or other else?Thanks Rob

[Check_Airman 3]

It was a PMDG random failure.

[KCA9304 0]

Hi,On my last flight, I got the following level 1 alerts in the cruise:AC TIE 3 OFFBUS AC 3 OFFAfter consulting the manual, I noticed that both RA's displayed amber X's, indicating a failure.Questions:What are the power sources for the RA's? I could find this anywhere, and I find it a little strange that they would have the same power source. Is this just a Microsoft limitation?I also noticed that although the RA's had amber X's descending trough 2500ft AGL, the indicator appeared as normal behind the X, and all RA callouts occurred normally. Can this be fixed?I was also expecting to see NO AUTOLAND displayed on the consequences page since the RA had indicated a failure, but it never appeared. The retard mode of the AT worked as normal for the landing. Is this a bug? How would the aircraft know when to enter RETARD and FLARE modes? Does it use BARO ALT in the event of RA failure?Paul

Paul,From my documents, this info:- RA1 powered by AC Bus 1, RA2 powered by AC Bus 3, so power sources are different. Don't know about MS limitations.- It would be normal for RA1 to indicate altitude as normal without a cross, RA2 to show a cross only.- Two working RA's are required to pass the Autoland test passing 1500 ft on approach, so No Autoland as a consequence would be normal.- Retard mode will operate as long as an RA is valid, there's no Baro Alt back-up.Regards,Harry

[mburkhard 23]

Thanks for the heads-up guys, this has been noted and brought to Michael's attention.Regards,Markus

[KCA9304 0]

Thanks for the heads-up guys, this has been noted and brought to Michael's attention.Regards,Markus

Hello Markus,When putting crosses at the right places:In this case AC Bus 3 failure: Also X's are missing for Right In-and Outboard Flap Indication.Regards,Harry

[Check_Airman 3]

Thanks guys,Would a single RA failure cause NO AUTOLAND or SINGLE LAND?

[KCA9304 0]

Thanks guys,Would a single RA failure cause NO AUTOLAND or SINGLE LAND?

Paul,Depends where the single RA failure takes place.To engage the LAND Mode (passing 1500ft on approach), two RA's have to be valid, If not: No Autoland (Approach only).If an RA fails after passing 1500ft, and in DUAL LAND mode, the system will downgrade to SINGLE LAND.As a single RA failure cannot be selected in the Failure Options Menu, there's no way to simulate it.Regards,Harry