OK, Here is the deal:
The temps were about sixties F. I got the fluid from www.evanscooling.com. If
the issue of the price of the coolant that will be added and kept in the
airplane is a factor, one might not consider flying as a recreation. The cost
is a drop in the bucket. The reason they are lowering the max CHT limit is
because with water in there, it is possible to boil the coolant before reaching
your CHT limit now - a highly undesirable condition. In normal ops, I do not
get over about 245 degrees F with the fluid now. In flying, the concern should
be non normal ops. We have had a Europa crash due to high coolant temps during
taxi out and then taking off, resulting in a boil over, explosion of the
overflow coolant bottle (not vented well, resulting in the problem - later
fixed by another SB) and fluid coming over the windshield, engine failure and
you can figure the rest. To me having the option to take the CHT all the way up
to 275F without concern about the coolant is a very valuable feature - it has a
boiling point of 375F. The claim is that there is better cooling due to no hot
spots va[osizing the water, but that doesn't seem to be what I am seeing right
now. If anything, it seems to be running warmer.
There is a reason they put out this service bulletin. If the cooling is
effective
enough for warm weather, I will be very happy to have it in there to have the
piece of mind of not dealing with cooling system boiling. The additional cost
to fill with this fluid vs. normal fluid is about $15 - hardly a factor in
my plans for retirement. The biggest issue for me is having to carry a supply
of the fluid on a trip in case of needing to top off the system.
A point of interest - the fluid I removed looked as clean as the day I put it in
there after 260 hours of engine running time.
Dave
A227
mini U2
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