Rubber fuel cells

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. How much should I expect the life expectancy
to be reduced? It there a proceedure to coat the inside of the bladders
with something that would preserve them? Thanks!

Mike
MU-2

Spray MMO inside them.
Jim

"Mike Rapoport" wrote in message
ink.net...
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. How much should I expect the life
expectancy
to be reduced? It there a proceedure to coat the inside of the bladders
with something that would preserve them? Thanks!

Mike
MU-2

I had bladders on my 182 and now have them on my Bonanza. Obviously the
best is to leave them full. I never had full tanks unless I was going a
long way, just wasn't going to put up with the decrease in performance
lugging around all that weight. What really hurts the bladders is to be
left outside in the baking sun, second is the temp change associated
with being outside. If there is any condensation as night falls now you
have water on the top of the bladder. This doesn't help bladder life.
The next best thing to keeping them full is an insulated hangar so
there's no sun damage and the change in temp is slow. New bladders now
a days last about 30 years, not keeping them full using the above
methods will reduce that to 25, so go for it. I didn't coat the
bladders with anything.



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. How much should I expect the life expectancy
to be reduced? It there a proceedure to coat the inside of the bladders
with something that would preserve them? Thanks!

Mike
MU-2

One of those air gun spayers. The kind that you hook to your shop air hose
with a suction tube that you stick in the container. Usually used to spray
solvents and wash engines. Attach a hose to the end of the tube so you can
insert it into the bladder and aim it around.
Jim

Thanks. I assmued that the lifespan was pretty long no matter what you did
to them. Since I use the out tanks so infrequently, I will probably coat
them with some preservative.

Mike
MU-2

"Newps" wrote in message
...
I had bladders on my 182 and now have them on my Bonanza. Obviously the
best is to leave them full. I never had full tanks unless I was going a
long way, just wasn't going to put up with the decrease in performance
lugging around all that weight. What really hurts the bladders is to be
left outside in the baking sun, second is the temp change associated with
being outside. If there is any condensation as night falls now you have
water on the top of the bladder. This doesn't help bladder life. The next
best thing to keeping them full is an insulated hangar so there's no sun
damage and the change in temp is slow. New bladders now a days last about
30 years, not keeping them full using the above methods will reduce that to
25, so go for it. I didn't coat the bladders with anything.



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. How much should I expect the life
expectancy to be reduced? It there a proceedure to coat the inside of
the bladders with something that would preserve them? Thanks!

Mike
MU-2

"Jim Burns" wrote in message
...
One of those air gun spayers. The kind that you hook to your shop air hose
with a suction tube that you stick in the container. Usually used to
spray
solvents and wash engines. Attach a hose to the end of the tube so you
can
insert it into the bladder and aim it around.
Jim



Thanks Jim! I already have the sprayer and the MMO (I use it for air-toll
lubrication). I may even have the hose! I assume that you spray the stuff
inside and drain any liquid out the drain valve? Is MMO viscous enough to
remain attached to the bladder walls?

Mike
MU-2

http://www.guardaircorp.com/content/spraygun.html

Jim

Yep.
Yep.
You can also use a piece of coated copper electrical wire to tie your hose
in a U or L shape to coat the top sides of the bladder. Wrap the tail of
the wire around the hose several times and it makes a handy handle to direct
the hose in all directions.

It's cheap and easy and you can re coat them any time you want.
Jim

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/

http://www-ext.tinker.af.mil/tild/to/0085a031.pdf

See page 37

cheers ... denny