when and how do you use prop heat?
do u switch on all the time?
or under certain condition?
Prior to entering the clouds at 0° C or below, in icing conditions any time, if ice builds up on the leading edge of the wings. In VMC on top I switch the prop heat off.
Operationally not critical, as it works as de-ice as well as anti-ice, unlike TKS. But I agree with highflyer and try to have it on before entering icing conditions. Preventing ice to form at all will also prevent little imbalances from ice not shedding at exactly the same time from the blades.
The one big issue with prop heat is that it needs to work on all blades. In my experience failure is not a rare event. If one blade is not heated and the others are, then using prop heat in icing conditions could result in catastrophic imbalance, and any amount of ice on the prop would be the lesser evil. For this reason I check prop heat before departure or shortly after departure. I tend to do that even if there is no chance of icing on that particular trip so that if there is an issue, it can be fixed before the next flight.
I have used two different systems – on one, testing is done by checking the current draw (e.g. should be 21A, if it is 14A then obviously only 2 of the 3 elements are working). On another airplane I fly there is a self test and the prop heat will switch itself off and announce FAIL if not working on all blades.
If the system stops working and there is risk of ice, depending on circumstances I consider going to max RPM.
Is there any aerodyamic heating of the prop leading edge, as there is (in a sufficiently fast aircraft) on the wing?
Maybe on the tips of the prop.
A TAS of about 350kt produces a delta T of 15C which should prevent icing in most conditions. So you can work it out 
2100 RPM on 78" diameter prop gives some 218m/s at the tip which is 422 knots
You need to take into account the reduction in pressure, also closer to the hub the velocity is lower, hence anti ice pads placed near the hub. If ice didn’t occur on propellers you wouldn’t need teflon nose guards on twins.
Goodrich Icex is a liquid that can be applied to the prop to prevent ice adherence. I use it on top of my electric prop heaters as a failsafe backup.
It is approved for 25 hours per application.
dirkdj wrote:
Goodrich Icex is a liquid
It is approved for 25 hours per application.
Wouldn’t that work on the wings as well then ? Less speed and no centrifugal force ?
I have looked and they say (I guess they have to, legally) that it is for the rubber part of de-icers.
But I guess it wouldn’t harm on a normal aluminium wing ?
