Usually you don't get a choice 
A heated prop is usually found on planes which use rubber boots on the leading edges.
A TKS prop is usually found on planes which have either the full TKS system (installed, or available as a factory option) or have no other ice protection at all.
My experience is only of a TKS prop and it is absolutely brilliant. I've had 30mm of ice on the leading edges and zero on the prop, and zero on the front window due to the droplets that come off the prop. The 2 litre bottle lasts me probably 2 years, which is just as well since the "approved" fluid costs about £200 for 20 litres (that was from Silmid). To be fair though, I don't spend much time in IMC below 0C... I think the 2 litres would last about 2 hours, on max flow rate. I use only the max flow rate, or nothing. The factory option was about £3k and is by far the best 3k one can spend on a plane.
Of heated props, I know only what others have told me, which is that they work fine, but the electrics can involve a fair bit of maintenance. I am hangared in a place where there used to be a prop overhaul shop, and they maintain a lot of bigger planes which mostly have heated props, and I see lots of bits like slip rings, carbon brushes, relays to cycle the power between the blades, and I often see stuff which is basically falling apart due to corrosion.
A TKS prop is a very simple mechanism. It is just simple metalwork, with no moving parts.
Whether the relative complexity of a heated prop translates to a significant maintenance cost (relative to the cost of operating e.g. a piston twin or a turboprop) I don't know.
The maintenance cost of a TKS prop system is nil, apart from having to replace the little pump every 10 or 20 years (a few hundred quid, I bet). It's important to run the pump regularly, to keep it working.
However if you have a full TKS system you could get through the whole fillup (£100-200 depending on what you use) in a couple of hours.
Does one use a tks prop as anti-ice or de-ice? I have heated prop and always turn it on below 0 in IMC.
Anti-ice, definitely. Switch it on prior to entering IMC below 0C.
Anti-ice, definitely. Switch it on prior to entering IMC below 0C.
I do the same although I have full TKS. Three days ago it wasn't enough to stop ice accumulating at leading egde - however, de-ice helped in few seconds.
I thought this is a VMC thread.
You can get condensation ice. It was last year in September on a flight from Coventry to Haßfurt. I was cruising FL160 with -15C OAT for some time, so the plane and the fuel got cold soaked (me too :)). There was a low inversion with very moist air trapped and visibility was not great, bot not a single cloud in sight. Due to the proximity to Frankfurt I got a late clearance to decent, so I had to give up quite a bit of altitude in a relatively short time.
In the rollout I noticed a bit ice on the wings about 2mm on the leading edge and around one mm even coating of the wing.
When I put the plane into the hangar a few minutes later it was covered with a few mm ‘hoar frost’ but you could see the structural members of the wing. A few minutes later it melted quickly considering the OAT was now 25C.
Yes this is possible, but freezing rain is extremely rare. I recall only one very brief instance (minutes) of it in 2000+hrs.
One can get icing on the pitot tube in VMC and this is why one should use pitot heat anytime near or below 0C.
One can get icing on the pitot tube in VMC and this is why one should use pitot heat anytime near or below 0CC
No, one should use pitot heat whenever airborne. I have no idea why people would do anything else.
Be very aware that on some types frost on the wing surfaces can be extremely detrimental. If you fly something slippery with a laminar flow wing it can very seriously affect you. It is particularly dangerous if asymmetric (frost on the wings on the ground, melted one side sat in the sun for example.) We used to keep a drum of deicing fluid with our AA5 (parked outside) to deal with precisely this problem.
There was a nasty accident to a Challneger in Birmingham a few years back caused by a thin layer of frost on a laminar wing.
Josh wrote:
We used to keep a drum of deicing fluid with our AA5 (parked outside) to deal with precisely this problem.
The expensive TKS fluid that you would put in the plane?
We had to remove some hoar frost a few times in the morning on our US trip, and used just the sun (which luckily was always out) and a rag/cloth to wipe the frost off. It always required two cycles because a bit of the humidity was left on the wing to re-freeze. It took almost an hour to get everything clean, but really didn’t want to take chances and try to take off with a contaminated wing in a Cirrus.
