Correction: on further inspection, the stuff comes out of both wings, if you pull a 2G turn.
I didn’t try different Gs to see how much it takes; it is prob100 dependent on how much fluid is in there. Currently mine is about 2/3 full.
And that 2/3 is enough to make a lot of fluid spurt out of the vent hole near the filler cap. One has to wonder why this has not come to light before, on a 30 year old STC. One possibility is that 99% of owners never look in the back of their plane, and probably most mechanics don’t spot it because that area is, in most TBs, full of dead spiders, leaves, all kinds of crap… and they probably think the “wet stuff” is just oil. I now understand why CAV sell that modified mount for the KG102A directional gyro (which is located right under the filler cap assembly). They probably think the reports of a TKS-fluid-damaged KG102A are due to spillage during filling, but actually the spillage occurs at every takeoff. I wonder if @TKS knows the story here?
I also found several serial connectors controlling the autopilot heavily corroded by liquid spill.
I always find TKS liquid all over the places in the back of the plane.
Now I have to replace and relocate all the cables and connectors that were fixed by the floor with new ones, as sometime the electric trim works intermittently :(
That is really unacceptable.
Those must have been the autopilot servos; the pitch and pitch trim servos are down there.
The roll servo is under the belly and – as posted further back up the thread – a TKS TB2x needs to have the belly panels silicone sealed otherwise TKS fluid gets into the belly and corrodes stuff there. I did do that… but I didn’t know about the huge spillage into the rear hull cavity.
Peter wrote:
The only drawback is that only one wing gets it, and I will leave it as an exercise to the reader to work out which one
Perhaps you aren’t flying a balanced turn 
I have just heard from someone with a TB21 who is no longer flying but who installed his system about 15 years ago:
There was a mod that came out a few years ago to insert a drain that runs from the filler area down to the bottom of the fuselage
No mention in the STC docs I got 
I was going to run a vent pipe to the top of the vertical stabiliser, but a bottom drain is a better idea. It needs to be ice protected…
Well, if there is spillage, the drain would be ice protected by the TKS fluid, and if there is no spillage, it doesn’t matter if it is blocked….
Haha that’s true but the vent isn’t there for spillage reasons. It is there to let air into the TKS tank as the fluid is being pumped out at the other end. So you get the same issue as with fuel tank vents: no clear vent → no juice coming out → engine or TKS stops working.
It is pretty obvious the solution is same as for the fuel tank vents. When you install the full TKS kit, you are required to install little vent protectors onto the fuel tank vents. I don’t have a pic to hand unfortunately. My TB20 already came with these protectors in 2002, as an apparently “off the books” job by the dealer or even the factory. So I have two spare ones from the TKS job.
The problem, which I am sure bothers “nobody” (in the sense that prob99 nobody has discovered it), is that you leave a trail of TKS fluid down the middle of the runway, on every takeoff So a better way would be to run the vent pipe up to the top of the vertical stabiliser and arrange it to come out in the protected airflow in the trailing area where no icing can take place. The resulting uphill section, about 2m high, should stop the stuff coming out during the takeoff run…
Vent —> Hose —> Large bottle inside the aircraft?
As long as there is an air gap in the neck of the bottle, and the hose does not go too far into it, this should catch the fluid nicely while allowing air to come in… at least until the bottle is full. And then, all it will do is “suck” TKS fluid back in.
I can’t wait to see the face of my FAA inspector when I eventually ask him to sign for such an installation :)
The procedure with an STC is that an A&P/IA checks the installation for conformance with the STC, fills in the 337 and sends that off to Oklahoma.
Ideally, obviously, the installation should be done by the same A&P/IA who is going to sign it off, otherwise you could end up over a barrel in the traditional way this often happens in aviation (many previous posts by people this happened to)!
All work (beyond pilot privileges) on an N-reg must be done by, or under the supervision of, an A&P, anyway.
How this installation works on an EASA-reg I don’t know, because there is no EASA STC. They told me they have a procedure…
