Dynon Avionics has been working with pilots who have reported issues with their heated pitot tube freezing up in icing conditions, and yesterday they issued a Service Bulletin to address the issue while they continue to work on the problem. Dynon is currently recommending that pilots with their heated AOA/Pitot probe should be operated as if the aircraft is equipped with an unheated AOA/Pitot probe.
Quoting the Service Bulletin:
Dynon Avionics has received reports from pilots who have experienced degraded airspeed indications while their Dynon heated pitot probes are in operation. Dynon Avionics has identified an issue where the pitot probe is unable to adequately separate and drain water that is encountered in some flight conditions. As a result, it is possible for water to enter the pitot system and subsequently freeze in unheated areas. This can cause inaccurate, fluctuating, or zero airspeed indications.
Dynon Avionics EFIS products use airspeed as part of the attitude calculation. While Dynon EFIS products have the ability to use GPS as a backup to airspeed, this mode is only active when the airspeed indication is zero. During inaccurate or fluctuating airspeed indications, Dynon EFIS systems (both SkyView and D10/D100 series) may not provide a reliable attitude indication.
For more information, and a complete FAQ from Dynon, visit: http://www.dynonavionics.com/docs/support_bulletin_050614.html