Originally Posted by
Step Turn
Most 100 series Cessnas have either one or two venting caps.
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They should all have 2 vented Caps as per an AD that applies to pretty much every Light Single Cessna.
For Cessnas with bladder tanks (some 180 series), venting is extra important. If the tank does not vent well, it'll unsnap itself from inside the wing, and collapse. Then wrinkles in the tank will prevent using all of the fuel, and it will not be possible to fill the full volume next time. Resnapping them into position is an unpleasant job
Wrinkles In Cessna bladder tanks are also a big issue because they will trap water that will not be removed by draining fuel from the quick drain.