Fuel Sight Gauges Turning Dark

[reileyr]

Has anyone else experienced plastic fuel gauges going dark? (See Pictures) The plastic on N998SC (June delivery, 2007) started turning darker after the first year and continually got darker. I inquired as to the cause and was told by CC that it was from using auto fuel. OK, except N998SC has never burned a drop of auto fuel, only 100LL. I decided to change out the sight tubes at the last conditional inspection and ordered the parts. After seeing how difficult it was due to the fairing being attached with sticky tape, I decided to wait. This years inspection will definitely require replacement of both tubes as it is near impossible to see the fuel level. But when I opened the package containing the new sight tubes, they are already showing signs of darkening even though they have not seen the light of day or been exposed to fuel. I hate to install these "new" tubes in this condition. What advice can CC and forum members give me about your experience? Thanks, Richard

BTW, here is a pilot quize. Are these fuel tanks full or empty or somewhere in between?

[txcub]

Mine are starting to turn dark also after four years but I have seen this on my previous aircraft (Husky) and they needed to be replaced. Jon

[Pete D]

You should not need to remove any panels that are held on by sticky tape. The bottom wing root panel is held on with #4 pk screws. Remove that and you should be able to access everything you need to. On a Sport Cub of that vintage the inboard screws are probably covered up by a "D" section of door seal right above the window. Current design has that "D" seal on the top edge of the window frame so you don't have to remove it every time you need to take that panel off.

Pete D

[reileyr]

Thanks Pete. Got sight tubes off.

How often are sight tubes being replaced on other aircraft? Are Jon and I they only ones? Maybe Texas 100LL?

[turbopilot]

Mine are turning dark as well. Gradual process since delivery in April 2010.

[Pilawt]

#62 (delivered Dec. 2007), sight gauges beginning to darken, but still usable. I hadn't even noticed it until this thread prompted me to check.

[Rich]

Mine are just beginning to turn dark too.

[Rich]

mine are just beginning to turn dark too.

sn 123

[Pete D]

I have not had any planes in the shop to change the sight gages. The company aircraft here in YKM live outside pretty much year round and while the sight gages are not as clear as new, they are definitely very usable. S/Ns 71-96, and 4-800+ hours.

Pete D.

[Clay Hammond]

While I can't quote you a part number or supplier that CC uses, that tubing is fairly ubiquitous. My dad has a roll of it on his shelf in the hangar that he's had for years. Folks, any sight gauge exposed to sunlight is going to fade/discolor over time. If the sun doesn't do it the dye in the fuel will. Even the old Piper sight gauges in Supercubs are known to do it on occasion. Have your mechanic look through one of the aviation supply catalogs, I'll bet you can buy a lifetime supply of that tubing for $30 or so. They come off and go on easy with nothing more than a Breeze Clamp holding them in place. Remove the lower side wing root fairing and you'll see.

Try this link:

http://www.aircraftspruce.com/catalog/appages/polyurethanetubing.php

0585-071.jpg

**Caveat** I am not a mechanic nor aircraft owner. In fact I'm even worse...I'm the son of an IA who's never bothered to finish his A&P and still flies his dad's airplanes instead of buying one of his own. Take everything I say with with a healthy dose of "he might be full of shit".