An anonymous reader quotes a report from The Register: Some models of Airbus A350 airliners still need to be hard rebooted after exactly 149 hours, despite warnings from the EU Aviation Safety Agency (EASA) first issued two years ago. In a mandatory airworthiness directive (AD) reissued earlier this week, EASA urged operators to turn their A350s off and on again to prevent “partial or total loss of some avionics systems or functions.” 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.” In layman’s English, this means that prior to 2017, at least some A350s flying passengers were suffering unexplained failures of potentially flight-critical digital systems.