Heated Pitot Operating Limits

[olechap]

I have a heated pitot AN5814-style (non-Dynon) on my RV-7. Recently while flying in -20C OAT, 150KIAS and light snow, my pitot line froze (had the pitot heat on since before takeoff). This has happened to me once before, and I thought it was just a fluke. When I slowed down and descended (guessing ~100KIAS, and -10C OAT) it unfroze and everything was normal. This made sense - lower heat load (airspeed & temp) required to do the thawing.

I am considering a replacement - and going to the Dynon Heated (to interface w/ my EFIS), but I'm afraid I'll still have this issue; granted it's rare that I fly this cold but I want to understand all limitations. I have tried to find typical ranges on exactly what a Pitot tube (any of them) can handle in terms of IAS & OAT, or how they're designed/tested, but have had no luck. Can anyone enlighten me to what the specs are of the Dynon heated probe (other than it draws x amps and is, indeed, heated)?

Thanks in advance!

 

[Dynon]

I'm afraid we don't have those sort of flight performance specs available. Our heated pitot is designed to prevent icing of the pitot in IFR flight conditions, but we can't give you a threshold of moisture / ice / OAT / speed etc that it can cope with. It's broadly designed to serve our customer use case (small GA aircraft, not including flight into "known icing" like you might see from a very high end certified aircraft, etc), but we just don't have the data in the form that you're after.