On 2005-09-12, Mike Rapoport wrote:
I have a Helio Courier with four fuel cells holding 30 gallons each. My
typical flight uses ~35 gallons so I would like to leave the outer (aux)
tanks empty most of the time. I understand that leaving them empty will
reduce their life expectancy.

My understanding is that the worst combination is mostly empty tank and
plane outdoors in the sun.

One suggestion I've seen (for Comanche owners) is that if you plan to
leave an aux tank mostly empty *but* you *are* going to fly regularly,
keep a gallon in each tank and let the splashing that happens in flight
keep the bladders from fully drying out.

Another thing to keep in mind is that dry tanks do shrink somewhat. I'm
not sure if it's due to actual shrinkage, or wrinkling, or what. Every
time I've left my aux tanks significantly below full for a while and then
filled them and let them sit, they've gained some capacity after sitting
mostly full. I haven't tried to quantify it, but I'd guess around a half
to a gallon in my 15 gal tanks.

--
Ben Jackson

http://www.ben.com/