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Date: Mon, 13 Sep 2010 13:53:21 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Scheduled hose replacement
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  On 9/13/2010 1:02 PM, David Leonard wrote:
>
>
>     *The radiator manufacturer will have a maximum number based on how
>     stiff the flat sided tubes are. Too much pressure rounds those
>     tubes and then pulls them loose from the fins when pressure is
>     removed. Also the rounded tubes slow airflow through the radiator. *
>     *Racing radiators tend to have higher pressure ratings than auto
>     radiators. *
>     *Most racers run 16 to 22 pound caps. Higher pressure means higher
>     boiling temp for the coolant.  Also more stress on the
>     connections. With a 2" hose and 22 pounds you have just about 70
>     pounds trying to pull the hose off of the fitting. With silicone
>     hose and safety wired clamps it would not be a factor. That does
>     not include Chinese replica clamps. Just real American made name
>     brand clamps. You can also use real aircraft quality clamps
>     already drilled for safety wire. *
>     *Many modern cars use no pressure cap. Just a sealing filler cap
>     on a make up bottle.*
>     *An air space above the coolant level provides a volume of air to
>     compress to control the pressure. If the moron at the gas station
>     fills that bottle all the way up while reading the message on the
>     bottle not to fill above this line,*
>     *the end tank will blow off of the radiator just like on my wife's
>     car. *
>     **
>     *The 22 pound cap is middle ground, a bit more insurance, not
>     likely to hurt the radiator. *
>     **
>     *I use 22 pounds. Distilled water with 10% glycol and either
>     Redline Water Wetter or 1/2 teaspoon full of dish washing
>     detergent. It is gentle on the hands. Never a problem since 1980.*
>     *Lynn E. Hanover*
>
>
> Hey Lynn and the rest of you smart guys, What is your opinion on 
> scheduled hose replacement?  My plane has been flying for 6 years now 
> and I just finished the annual.  I decided that 6 years was long 
> enough on some of my radiator hose and decided to replace it.  In 
> particular, I ordered up the AN-16 steel braided hose (Earls 
> Perform-o-flex)  for my coolant out line but I just couldn't bear the 
> thought of cutting and fitting that stuff and hoping I don't get leaks 
> or damage the AN hose fittings or cut my fingers to shreds.  So I 
> decided the current hoses were good for another year.  Maybe a 
> justification...
>
> Opinions on scheduled replacement of SS hose?
>
> -- 
> David Leonard
>
> Turbo Rotary RV-6 N4VY
> http://N4VY.RotaryRoster.net
> http://RotaryRoster.net
I would copy the guy with the most trouble free hours on his coolant 
hoses. :-)

Charlie