Voici le résumé de lincident; tu peux trouver la consigne de navigabilité de l EASA en 2014 (toujours valide) . Les N° sont AD est 2015-0087 et -0089 pour les 330 et 340.
The BFU reported that accordinateurng to flight data and cockpit voice recorder the first officer (35, ATPL, 6,473 hours total, 5,179 hours on type) was pilot flying, the capt'ain (52, ATPL, 16,384 hours total, 12,414 hours on type) pilot monitoring. After the aircraft climbed clear of top of clouds at about FL200 the flight data recorder recorded a fixed value of +4.2 degrees for the left hand AoA sensor, less than a minute later the FDR began to record a fixed value of +4.6 degrees for the right hand AoA sensor. The aircraft subsequently turned to fly direct to LATEK waypoint, during this turn the capt'ain noticed the Alpha Protection Band had unusually and significantly increased. The first officer therefore reduced the climb rate from 800 to 500 feet per minute to enable the aircraft to accelerate. A short time later the first officer disengaged the autopilot and gave a brief nose down input.
The aircraft however continued to pitch down, inputs to counter the pitch down remained without effect. About 45 seconds after the nose down began the first officer alerted the capt'ain who took control of the aircraft, that at this time had reached a rate of descent of 4000 feet per minute and a pitch of -3.5 degrees. The capt'ain provided a maximum nose up input which caused the aircraft to pitch up again and the rate of descent decreased and the aircraft entered level flight.
The capt'ain was able to maint'ain altitude by providing a continuous nose up input deflecting the side stick about 50% of its travel. The autopilot could not be engaged again, and a manual nose up trim was not possible.
The crew checked for related checklists but did not find an'y. The crew reset the Flight Augmentation Computers 1 and 2 in sequence with no effect.
8 minutes after the aircraft began its descent the Aircraft Communications Addressing and Reporting System (ACARS) issued an automated information to dispatch showing the three AoA sensor values amongst other data.
21 minutes after the aircraft began its descent the crew sent a message to maintenance checking whether a simultaneous reset of all FACs would be possible. Maintenance replied in the positive stating that the aircraft would revert to alternate law as result. Another 7 minutes later the crew reported they needed to constantly pull on the sidestick, trim was inoperative and autopilot could not be engaged and the Alpha Prot Band came up extremely quick. In addition the crew received a message "PH6 AOA3" on the centralized fault display s'ystem (CFDS). Upon suggestion by maintenance the crew switched off the air data reference unit (ADR3), however, without effect. ADR3 was reengaged. Another 12 minutes later maintenance wrote a message to the cockpit along the lines "after review of the data we found the values for AoA 1 and AoA2 appear to be frozen and report too high an angle of attack. If the problem persists, disengage ADR1 and ADR2 which will cause the aircraft to revert to Alternate Law however." then followed up "perhaps it is sufficient to just disengage ADR2".
The crew disengaged ADR2 which immediately prompted the aircraft to revert to Alternate Law and it was no longer necessary to pull the nose up.
The crew decided to use the remaining hour of flight time to verify the s'ystem status and to prepare for landing and landed safely at the destination.
Source Avherald
