A320 #3 ADIRU OFF - Disregard Spds on PFD?
There's an MEL (34-10-01-ADIRU) that allows for #3 ADIRU to be selected OFF if it's faulty provided we disregard the the characteristic spds ( VLS, F,S, Green dot) on the PFD in favour of the QRH numbers.
I'm not sure I understand why. Any thoughts?
Is this FAC issue and the need for a crosscheck with CAPT's TAT data?
In the absence of a pitot ht failure messing up the #1 and 2 air data, I'm inclined to think the PFD spds are fine as long as they're checked periodically against the QRH.
Any feedback would be appreciated.