wing fuel gauge

[Ulysse]

my wing fuel gauges have some condensation in them which makes it difficult to read them from the cockpit. Is there a way to remove this water ? Is it possible to buy new gauges ?

[Guest]

New sight gauges are available if needed.  They can be carefully removed with a very small flat blade screwdriver, once removed put it in a bag of rice for a few days to see if it dries out. If it does, bond it back in with clear silicone.

Clarence

[Boilermonkey]

I guess you can put your wet cellphone next to it too?   That's great advice, thanks Clarence.

[Mark89114]

1 hour ago, M20Doc said:

New sight gauges are available if needed.  They can be carefully removed with a very small flat blade screwdriver, once removed put it in a bag of rice for a few days to see if it dries out. If it does, bond it back in with clear silicone.

Clarence

I was under the impression we arent supposed to use silicon due to the acidic component?

[Guest]

3 minutes ago, Mark89114 said:

I was under the impression we arent supposed to use silicon due to the acidic component?

I should have said Dow 732.

[Ulysse]

3 hours ago, M20Doc said:

They can be carefully removed

Thank you!

[PT20J]

3 hours ago, Mark89114 said:

I was under the impression we arent supposed to use silicon due to the acidic component?

Silicone is a polymer; silicon is an element 

But seriously, this is something that I've heard but I'm not quite sure if it's real or just an old wives' tail. There are two main types of RTV; acetoxy cure and oxime cure. The former releases acetic acid (and has a vinegar smell) during curing, and this seems to be the cause for concern. But, the acid is only released during cure. Aluminum is pretty tolerant of acetic acid. A mild etch would improve adhesion. I checked both GE and Permatex websites and both recommend it for metal and don't have any warnings about aluminum. Any chemists amongst us want to weigh in?

80050.pdf

[carusoam]

not a chemist but…
 

Silicone has changed over the years…

The old gave off a really strong aroma… you wouldn’t/couldn’t miss it…

Following Doc’s advice above will probably keep you in the ballpark…. 
 

A good painter’s tape to hold the device in place while curing…

New ones have been known to leap out during the first flight…

Probably a 24+ hour cure time for that…

Best regards,

-a-

[PilotX]

Rice is better than using a lamp. We had initially tried to use a lamp with CFL to remove condensation while leaving it in the wing. No bueno. Pop it out because you will need to find where the crack is or have the same issue. I later figured out that the bottom of mine had cracked but we had warped it pretty good by then. 

[PT20J]

On 7/11/2021 at 9:29 AM, M20Doc said:

I should have said Dow 732.

 

On 7/11/2021 at 1:06 PM, PT20J said:

But seriously, this is something that I've heard but I'm not quite sure if it's real or just an old wives' tail. There are two main types of RTV; acetoxy cure and oxime cure. The former releases acetic acid (and has a vinegar smell) during curing, and this seems to be the cause for concern. But, the acid is only released during cure. Aluminum is pretty tolerant of acetic acid. A mild etch would improve adhesion. I checked both GE and Permatex websites and both recommend it for metal and don't have any warnings about aluminum. Any chemists amongst us want to weigh in?

80050.pdf 127.93 kB · 3 downloads

I looked up the TDS for Dowsil 732. It is acetoxy cure. See note below. However, if Clarence has been using it with no ill effects, I doubt it’s an issue. 

If you are worried about it, GE makes a Silicone II RTV specifically for aluminum.

Silicone II ALuminum & Metal - TDS.pdf