TKS Question... Dead Spot

[alextstone]

On 11/24/2020 at 10:18 AM, CAV Ice said:

I would recommend TKS fluid with a lint free cloth as it can get into the porous membrane and tends to pull fluid to the surface.  I've had success wiping the leading edge while running the system to pull fluid out of dead spots.  If all else fails, we do have a purge procedure that isolates individual panels.  If solvent has damaged the porous membrane you will know it.  Fluid will typically squirt out of the panel 3-6 inches like a shower from the solvent damaged area. 

I had a panel at the wing root of the right wing that would not weep correctly in flight or on the ground.  Although it was SLOWLY improving over time, I wanted to accelerate the process and rule out any big problems.  I followed @peevee 's post in a related thread found here and I built this:

 

As @peevee mentioned, you will need the appropriate sized Olives, seals, connectors and a clenching tool to compress the olive onto the tubing purchased in advance from @CAV Ice.  In my case, I elected to purge all of the wing panels at the same time because the TKS proportioning valve is mounted in a rib located at WS 133 with the inlet side facing the fuselage.  It so happens that there is an inspection panel on that side of the rib that is screwed in place.  In order to reach the outlet side of the proportioning valve, I would have had to drill out rivets in another inspection panel.   I followed the Mooney Bravo Maintenance manual pages 136-138 for Level IV TKS service.  There is a max allowable pressure noted of 40psi / 2.6 bar to which I adhered. Here is a view of the location of the connection to the proportioning valve:

 

 

Here is the view of the inboard panel during the purge:
 

 

The temp in the hangar was about 50 degrees during the purge.  I presume this is partly why the upper surfaces do not weep as much as the lower surfaces.  The panel seems to me to be weeping properly now in that subjectively, it is weeping at the same rate as the other panels.  

 

Alex

[philiplane]

If you really want to test the system, empty the TKS tank. Put the TKS in the freezer overnight, then put it in the plane (which needs to be as cold as possible). 

These systems will not work as intended unless they are COLD. Even 50 degrees is not cold. At temperatures above 50, the panels will not always wet out to the ends. The fluid is too thin. Chilling the fluid will help replicate cold soaked flight conditions.

[alextstone]

18 hours ago, philiplane said:

If you really want to test the system, empty the TKS tank. Put the TKS in the freezer overnight, then put it in the plane (which needs to be as cold as possible). 

These systems will not work as intended unless they are COLD. Even 50 degrees is not cold. At temperatures above 50, the panels will not always wet out to the ends. The fluid is too thin. Chilling the fluid will help replicate cold soaked flight conditions.

Thank you for the reminder.  The panel in question was not functioning properly during high altitude flights as cold at -25 deg C.   The purge procedure seems to have been successful in that it now wets across its length and the top half wets at 50 degrees, although the flow rate through the top half is much slower at that temp. 

[AZOutlaw]

Currently doing the annual and we tested the TKS yesterday.  I had a low pressure flashing red for a long time and then found fluid leaking from the filter canister in the belly.  We removed and inspected and then reinstalled and eventually got the fluid flowing, without the leak.  Question is, how often should that filter be replaced, and where do I find one?

I'd also be interested in others tricks or ideas to get things flowing.  I've learned that the low pressure light will flash forever, and the system won't prime, unless you toggle the windshield switch a few shots to prime.  I also get the high pressure light on after the low pressure light quits flashing.  Is "high pressure" telling me that all is good or that it's too high?

[CAV Ice]

@AZOutlaw sent you a PM

[apenney]

1 hour ago, AZOutlaw said:

Currently doing the annual and we tested the TKS yesterday.  I had a low pressure flashing red for a long time and then found fluid leaking from the filter canister in the belly.  We removed and inspected and then reinstalled and eventually got the fluid flowing, without the leak.  Question is, how often should that filter be replaced, and where do I find one?

I'd also be interested in others tricks or ideas to get things flowing.  I've learned that the low pressure light will flash forever, and the system won't prime, unless you toggle the windshield switch a few shots to prime.  I also get the high pressure light on after the low pressure light quits flashing.  Is "high pressure" telling me that all is good or that it's too high?

Speaking of fluid leaking....I was filling with TKS the other day and the sound was different than usual....like pouring something into a plastic container and loud.  After about 3/4 gallon I stopped when I noticed a rapid flow of fluid coming out of a drain under the fuselage.  So I opened up the left side access panel and discovered the the fill hose had detached from the fill port.  The hose clamp had slipped off apparently and I was pouring TKS into that space - yikes!  I reattached the hose.  I will now look down into the fill port to verify that the hose is still attached before filling.

[StevenL757]

On 12/26/2020 at 10:30 PM, philiplane said:

If you really want to test the system, empty the TKS tank. Put the TKS in the freezer overnight, then put it in the plane (which needs to be as cold as possible). 

These systems will not work as intended unless they are COLD. Even 50 degrees is not cold. At temperatures above 50, the panels will not always wet out to the ends. The fluid is too thin. Chilling the fluid will help replicate cold soaked flight conditions.

For those who appreciate data, here's the dynamic viscosity chart from CAV.

[aviatoreb]

On 1/5/2021 at 1:06 PM, apenney said:

Speaking of fluid leaking....I was filling with TKS the other day and the sound was different than usual....like pouring something into a plastic container and loud.  After about 3/4 gallon I stopped when I noticed a rapid flow of fluid coming out of a drain under the fuselage.  So I opened up the left side access panel and discovered the the fill hose had detached from the fill port.  The hose clamp had slipped off apparently and I was pouring TKS into that space - yikes!  I reattached the hose.  I will now look down into the fill port to verify that the hose is still attached before filling.

When I first got the airplane, I didn't have a good idea how much to fill into the system, and I didn't notice that I was actually spilling a lot a lot on the ground.  So there was a pool of tks under the tail.  I assumed it was like alcohol and would just evaporate quickly.  Which it didn't.  When I came back two days later, not only was the pool of tks on the floor still there.  There were several mice dead in the pool who seemed to think tks fluid would make a tasty beverage.