The Australian Transport Safety Bureau said it was advised on Dec. 27 of an occurrence that day involving a QF A330-300 cruising at 36,000 ft. on its way from Perth to Singapore. Some 260 nm. northwest of Perth the autopilot disconnected and the crew received an Electronic Centralized Aircraft Monitor message (NAV IR 1 fault) indicating a problem with ADIRU No. 1.
The crew implemented the new Airbus Operations Engineering Bulletin procedure by selecting the IR 1 and ADR 1 pushbuttons to off (ATWOnline, Oct. 15, 2008). The aircraft returned to Perth.
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At this stage of the investigation, the analysis of the available data indicates that the air data inertial reference unit (ADIRU) 1 abnormal behaviour is the likely origin of the event," the Australian Transport Safety Bureau (ATSB) says in a statement today, referring to an incident that occurred on 7 October while the Qantas A330 was enroute from Singapore to Perth.
"The faulty ADIRU unit continued to feed erroneous and spike values, for various aircraft parameters, to the aircraft's flight control primary computers."
This "led to several consequences including: false stall and over-speed warnings, loss of altitude information on the captain's primary flight display and several centralised aircraft monitoring system warnings."
Because the ADIRU 1 generated very high, random and incorrect angles of attack it meant that "the flight control computers commanded a nose-down aircraft movement, which resulted in the aircraft pitching down to a maximum of 8.5 degrees."
It also "triggered a flight control primary computer pitch fault".
Voici l'AD qui en découle
Ca a à priori bien fonctionné pour le second incident...
Avec un petit rappel historique sur le 777
Old software reinstalled to fix 777 avionics glitch
The emergency AD follows a Boeing service bulletin issued on 26 August, itself the result of an ongoing investigation into the 1 August failure of a Malaysia Airlines 777-200ER flight management system while climbing through 36,000ft (11,000m) soon after take-off from Perth airport in Australia
Tout ce passe dans le secteur de Perth au passage...
Enfin, mais je n'arrive plus à remettre la main dessus, il me semble qu'une AD avait également été émise pour des cas de montages en cours de maintenance d'ADIRU "incompatibles" entre elles (de différents fabricants ?).
Avion moderne, beaucoup de neurones planqués derrière le tableau de bord ! Nouvelles contraintes de qualité sur la maintenance?