If you don't have a slippery plane why pull the power at all for
descents? In my 182 I close the cowl flaps if they aren't already and
simply roll in two swipes of nose down trim. Leave power as is, which
for me is almost always top if the green throttle and prop or the max it
will give me. Bingo, 500 fpm down. Don't even get into the yellow.



Ray Andraka wrote:
For descents, I just pull back my MP about 4" for 500 fpm. Don't touch the
mixture until leveling back off, don't touch the throttle, don't touch the
trim. Most times, this won't register as shock cooling on my JPI, and the
times it does it just over the 50 deg/min alarm limit. This technique keeps
your airspeed constant, and makes for a minimum pilot load, and cools the
cylinders gently. PIC taught me the technique in one of my instrument
refreshers.

Aaron Coolidge wrote:


: Given that cylinders are 1k each, I'll keep the temps up on decent when
: possible. I mean how hard is it to pull back to 2,000 RPM instead of
: idle??? Yeah, it's probably a waste of gas but I'm burning the cheap
: stuff
: anyway.

: That about sums up my feelings, too.

: We can't prove that it exists, but the very threat of a cracked cylinder
: head due to shock cooling is enough to make us fear it, and fly like it's
: real.

Don't forget another pilot-induced mechanism to lead to rapid cylinder
head cooling: pushing the mxture full rich at the top of descent, while
simultaneously reducing the throttle a modest amount. At this point, the
pilot could probably lean the mixture more, or leave it leaned for cruise,
until time to add power to level out.

--
Aaron Coolidge (N9376J)


--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759