We have the legacy G3X system, with a backup (round dial old school) airspeed indicator. The plane passed IFR pitot/static test a few months ago. Our airspeed indicators (both the electronic one through the G3X and the old school back round dial one), both have started fluctuating up to 15 to 20 knots. It comes up to speed, then both dropped really quickly (a second or 2), then slowly climb back up. It pulses like this through the entirety of the flight. The faster and higher you go, the bigger the variation. Pitot blockage??
Don
Don