Cessna Wing Skins

Don't drill out those rivets! They are only holding a circular
gasket flange ring on the top skin. After all the screws are out, you
have to be a little less gentle with that skin and lift it enough that
the gasket flange ring will clear the tank neck and allow the skin to
slide out from under the leading edge skin and cabin roof skin.
Cessna wants those skins off every 1000 hours, and there's good
reason. We have found broken tank restraining straps, missing strap
chafe protection, rubber tank support and top skin straps rotted away
and the tank rubbed through (or almost through) against aluminum
structure, fuel stains around the filler neck weld indicating a crack
that could suddenly get serious, and so on. (Line boys with their big
fuel nozzles tend to let the tank neck take the hose weight, and that
cocks the tank neck and cracks the weld.) Once the mechanic has done a
couple of these inspections they're not a big deal. The skins are much
harder to get back into place thatn they are to take out, especially if
the tank was moved a bit; the filler neck will no longer line up with
the skin when the skin's screw holes are lined up with the wing's
holes.
You'll need a couple of new gaskets for the filler neck, at
typical Cessna prices.

Dan

Thank you very much Dan for the info.
Tom
wrote in message
ups.com...
Don't drill out those rivets! They are only holding a circular
gasket flange ring on the top skin. After all the screws are out, you
have to be a little less gentle with that skin and lift it enough that
the gasket flange ring will clear the tank neck and allow the skin to
slide out from under the leading edge skin and cabin roof skin.
Cessna wants those skins off every 1000 hours, and there's good
reason. We have found broken tank restraining straps, missing strap
chafe protection, rubber tank support and top skin straps rotted away
and the tank rubbed through (or almost through) against aluminum
structure, fuel stains around the filler neck weld indicating a crack
that could suddenly get serious, and so on. (Line boys with their big
fuel nozzles tend to let the tank neck take the hose weight, and that
cocks the tank neck and cracks the weld.) Once the mechanic has done a
couple of these inspections they're not a big deal. The skins are much
harder to get back into place thatn they are to take out, especially if
the tank was moved a bit; the filler neck will no longer line up with
the skin when the skin's screw holes are lined up with the wing's
holes.
You'll need a couple of new gaskets for the filler neck, at
typical Cessna prices.

Dan

wrote:
Cessna wants those skins off every 1000 hours, and there's good
reason. We have found broken tank restraining straps, missing strap
chafe protection, rubber tank support and top skin straps rotted away
and the tank rubbed through (or almost through) against aluminum
structure, fuel stains around the filler neck weld indicating a crack
that could suddenly get serious, and so on.
snip

I'll second that assessment. Tank skins need to be pulled far more
often than most people bother to pull them. The OP's mechanic is doing
his job.

See our recent experience on my site. Click through:

Aviation-Articles-Maintenance-Fuel Tank Repair

-Doug

--------------------
Doug Vetter, CFIMEIA

http://www.dvcfi.com
--------------------

Good one. Thanks!

On 24 Apr 2005 20:01:30 -0700, wrote:

Don't drill out those rivets! They are only holding a circular
gasket flange ring on the top skin. After all the screws are out, you
have to be a little less gentle with that skin and lift it enough that
the gasket flange ring will clear the tank neck and allow the skin to
slide out from under the leading edge skin and cabin roof skin.
Cessna wants those skins off every 1000 hours, and there's good
reason. We have found broken tank restraining straps, missing strap
chafe protection, rubber tank support and top skin straps rotted away
and the tank rubbed through (or almost through) against aluminum
structure, fuel stains around the filler neck weld indicating a crack
that could suddenly get serious, and so on. (Line boys with their big
fuel nozzles tend to let the tank neck take the hose weight, and that
cocks the tank neck and cracks the weld.) Once the mechanic has done a
couple of these inspections they're not a big deal. The skins are much
harder to get back into place thatn they are to take out, especially if
the tank was moved a bit; the filler neck will no longer line up with
the skin when the skin's screw holes are lined up with the wing's
holes.
You'll need a couple of new gaskets for the filler neck, at
typical Cessna prices.

Dan