Airbus A350-900 operators are being instructed to reset the aircraft's electrical power system regularly to avoid spurious effects on the type's avionics.
Analysis has determined that the problems can occur after 149h of continuous power-up of the twinjet type.
The European Aviation Safety Agency is ordering operators of the A350 to conduct an on-ground power cycle regularly, resetting the internal timer, to ensure that the system stays within the 149h interval limit.
It has drawn up an airworthiness directive in response to in-service incidents involving loss of communication between certain avionics equipment.
"Depending on the affected [aircraft] systems or equipment, different consequences have been observed and reported by operators," says EASA.
It says the condition could lead to "partial or total loss" of certain systems or avionics functions.
EASA says the directive is an "interim measure" and that it could take further action to address the situation.
Similar internal timer problems have previously emerged on Boeing 787 generator control units, as well as within engine power-management systems on the Airbus A380.