A320 ADIRS POWER UP
 

Should there be any delay when switching ADIRS ON to check for battery power individually ?

Hi,

There is no requirement to check the ON BAT light during the alignment. Airbus procedures mention that the light will come on "during 5 s" but that's about it.

If you turn all three IRS on quickly and the On Bat light stays on then you have to figure out which IRS is defective.This is why I turn them on slowly and watch the light illuminate and then extinguish for each IRS. I remember an A306 that had a problem with the DC circuity of an IRS so for me it is an old school practice.

won't such defect show up as a failure?

Ground Warning If one of the 3 ADIRU's looses 115 VAC power (the ON BAT light on the ADIRS illuminates illuminates), the 'HORN MECH CALL' sounds with a time delay of 15 seconds, if the A/C is on GROUND. Parallel to this the ADIRU & AVIONICS VENT light in the nose well illuminates.

IIRC, only IRS 1 is powered by battery in emer elec config. The other two are powered on ground only for 5 minutes or so... I guess checking the 2 and 3 On bat is pointless...

C_Star,

In Emergency Electrical Configuration, IR3 can replace IR1 using ATT-HDG selector ( QRH, Abnormal and Emergency Procedures, 24.01C, 9 SEP 2015 )

is there a way to check that with the IRS manufacturer

Check what? Power supply architecture to boxes?

FD.

If you select IR3 to Capt before you go into Emer elec config you keep two IRs and can do an autoland.

In that case IR3 will be supplied instead of IR1 but not both.

I guess TL suggests that unlike AC ESS, the HOT BAT 2 would not be affected by the switching thus providing for 2 ADIRUs power.

http://i63.tinypic.com/1265hrd.jpg

The reason given by airbus was checking individual IR on BAT ensures that full alignment is taking place for each one.

That seems to me so far the best reason.

So is it an Airbus FCOM procedure?

FD
Since FCOM is silent on this I asked airbus specifically and they answered me.

Thank you. Best regards, FD.