takata;
If power was lost, what happened to FDRs records? are they stopped also in this aircraft?
The DFDR is powered by the AC2 bus which would be lost in the Emergency Electrical Configuration, (loss of both generators). I believe the CVR is similarly powered. The recorders will have stopped operating the moment AC1, AC2 and DC1 buses were unpowered. The
ATSU [Air Traffic Service Unit] contains the
ACARS and
CMS [Central Maintenance System] as well as other functions and has inputs from the
FMS [Flight Management System],
FWC [Flight Warning Computer],
DMC, [Display Monitor Computer] and
SDAC [System Data Aquisition Concentrator],
SATCOM control and #3VHF input would also stop once these buses were unpowered.
Regarding any loss of airspeed information and disconnection of the autopilot/autothrust, the immediate key in responding is to do nothing initially except to pull the thrust levers out of the CLB detent and set the EPR/N1 where it was just prior to the failure, and strictly maintain the same attitude. This would be challenging in heavy turbulence and darkness with no horizon.
Flight in Alternate Law is just not an issue. The A330 becomes an ordinary aircraft, easily controlled providing one is, as with any heavy transport at high altitude, gentle with the controls. The sidestick does provide enormous power vice a control column/wheel however.
If the thrust levers were left in the CLB [Climb] detent with loss of the autothrust system, the aircraft would slowly, (
very slowly) accelerate towards VMO but it would take a long time...10-15 minutes; there is not a lot of reserve thrust remaining at these altitudes and weights. That assumes still air of course. In heavy turbulence, strongly-rising columns within a TCu we cannot say anything that is certain.
Also, I do not believe a full turn-back was attempted though an
altering of course is entirely possible. A turn-back is a very drastic course of action with many other mitigating actions available before such a decision would be indicated, (this assumes that radar was on, used and correctly interpreted). I say this because of the time involved for such a maneuver. A 180deg turn, discussed last August on the second original thread now in Tech Log, would take just under seven minutes and cover a diameter of just under 14nm, (463kts TAS, 25deg bank, still air). The max bank achievable on autopilot using the heading select is 20deg so anything steeper requires a disconnection and hand-flying. Under circumstances of heavy turbulence, darkness and a degrading autoflight system with associated warnings, that too would be a challenge.
It has been observed the ending of the ACARS messages does not necessarily mean the end of the flight so we don't know the timings.
We know that the radome was not damaged in flight because of the damage pattern it does exhibit, (lower area shattered/missing, upper area intact but damaged - I do not recall any other damage such as hail damage, being cited), so we can assume the radar was functionable though we cannot say it was on, even though that is a good assumption.
PJ2