EASA 2019-0144

Requires amendment of the applicable AFM and, for certain airplanes, modification of the total air temperature (TAT) probe heater electrical circuit. Occurrences of pitot-tube blockage were reported, leading to in-flight air data loss. Investigation results indicated that accumulation of water and subsequent freezing was the failure cause. This condition, if not corrected, could lead to unreliable indication or loss of in-flight air data provided by systems deriving their data from measuring air pressure, possibly resulting in loss of control of the airplane.