ADR Faults
Greaybeard:
When the system compares ADR data and sense one is going astray, it disregards and eliminates that source and only uses the 2 remaining.
ADR DISAGREE comes on after, when the 2 remaining ADR don't agree either. It's the PRIMs (F/CTL computer) that reject this data. Resetting them will not restore Normal Law.
Thresholds to reject an ADR : CAS and TAS, 16Kts for 10s, MACH 0,05 for 10s, ALT 3000ft for 1s, AOA 3,6 for 10s, Static pressure 5HPA for 1s. This means a sudden and significant variation of the ADR data will eliminate that Air data source !
Since the air data is corrupted, erroneous, wrong or along those lines, the FMGEC eliminates the CAS from the PFDs (SPD LIM Red flag, loss of "Vls").
Also, the A/C being in "Alternate Law without portections", the "flight envelope" parts of both FMGECs are considered INOP !! thus triggering a fault message on the FMGECs.
Note that the LOAD FACTOR protection is still working !!
Similar incident on another A330, another company, another day, but with same pitots, WAS attributed to icing of the probes! It lasted 2 minutes 20s, from 22h22,20s to 22h24,40s (reengagement of FDs and APs !!) and triggered ECAM messages and PFD flags similar to AF447 ACARS messages.
For 1m26s, the PF is in manual flight, without APs, without FDs, without FPV (Bird) and without A/THR.
Cheers
Last edited by captainflame; 15th Jun 2009 at 08:11.