Airbus A350 software bug forces airlines to turn planes off and on every 149 hours
The revised AD, effective from tomorrow (26 July), exempts only those new A350-941s which have had modified software pre-loaded on the production line. For all other A350-941s, operators need to completely power the airliner down before it reaches 149 hours of continuous power-on time.
Concerningly, the original 2017 AD was brought about by "in-service events where a loss of communication occurred between some avionics systems and avionics network" (sic). The impact of the failures ranged from "redundancy loss" to "complete loss on a specific function hosted on common remote data concentrator and core processing input/output modules".
Airbus' rival Boeing very publicly suffered from a similar time-related problem with its 787 Dreamliner: back in 2015 a memory overflow bug was discovered that caused the 787's generators to shut themselves down after 248 days of continual power-on operation. A software counter in the generators' firmware, it was found, would overflow after that precise length of time. The Register is aware that this is not the only software-related problem to have plagued the 787 during its earlier years.