ACARS MEssages Partially Decoded
the data available (ACARS
messages) at this stage:
-Does not suggest any loss of electrical power
-Does not suggest loss of cockpit display units
The majority of the messages are linked with unreliable airspeed
measurement
• Some additional messages are also consistent with unreliable
airspeed measurement but require further analysis (hopefully we can all try piece together some info from this)
• Others resulted from crew action
02:10 UTC Maintenance message
“PROBE-PITOT 1+2/2+3/1+3(9DA)”
2 different sources of trigger:
The EFCS detected a speed decrease greater than 30kts in 1s on 2 or 3 airspeed measurements.
The AFS detected that each airspeed information compared to the 2 others showed at least transiently a difference greater than 20kts
The Above Message, as per its design, triggered the following messages:
“FCTL ALTN LAW”
“AUTO FLT REAC W/S DET FAULT”
“FLAG ON CAPT PFD SPD LIMIT” and “FLAG ON F/O PFD SPD LIMIT”
-Indicates that characteristic speeds information
(VLS, VMAX….) were no more displayed on PFD
-Information displayed on both PFD speed scales
* current airspeed, selected airspeed
* SPD LIM flag on bottom of airspeed scales
“AUTO FLT AP OFF” - Auto disconnect of AP
“AUTO FTL ATHR OFF” - Again auto disconnect of ATHR as above
“FLAG ON CAPT PFD FD” and “FLAG ON F/O PFD FD” A red flag FD was displayed on both PFD (attitude area) to indicate that FD were disengaged but selected ON
At 2:10 UTC message “F/CTL RUD TRV LIM FAULT”
Indicates that the FCPC detected a speed variation higher than 50kts in 10s on 2 or 3 airspeed indications
Indicates that the rudder travel limit is locked at the position corresponding to the speed immediately before the detected speed variation
02:12 UTC “NAV ADR DISAGREE”
-The Flight Control System had already rejected one ADR AND
-Out of the 2 remaining ADR’s, the Flight Control System detected a discrepancy on one ADR parameter
Other maintenance messages and cockpit effects pointing at
ADR system:
02:10 UTC
–“FCPC2 (2CE) WRG: ADIRU 1 BUS ADR1-2 TO FCPC2”
–“MAINTENANCE STATUS EFCS1”
–“MAINTENANCE STATUS EFCS2”
02:11 UTC
–“ISIS (22FN-10FC) SPEED OR MACH FUNCTION”
–“ADIRU2 (1FP2)”
02:14 UTC
–“MAINTENANCE STATUS ADR2"
In Relation to other messages triggered:
02:13 UTC
–“F/CTL PRIM1 FAULT” and “F/CTL SEC1 FAULT” - SHows PRIM 1 and SEC 1 were either both switched to off or Reset.
"FMGEC1 (1CA1)”
02:14 UTC
–“ADVISORY CABIN VERTICAL SPEED” - This indicated Cab Vertical Speed was greather than plus or minus 1800ft/min
All pieced together from a prelim round up and also trying to shed some light on this