Posted for "George Shattuck" <kloop@plantationcable.net>:

 This is interesting engine management.  I'm not so sure that a low power
setting (15 inches MAP) during a long descent, then full rich mixture plus
switching fuel tanks around near the bottom of the descent is the best way to
go.
 
 I don't claim to be an expert, far from it as a matter of fact, but I have
sat behind and managed my little IO-320 over 1000 hours and would like to
offer my operating procedures for some more reference.
 
From around 8,000 to 10,000 feet I will usually begin a descent from 35 plus
miles out by reducing the RPM to 2200 and trimming to 700 FPM rate of descent.
 I don't reduce the MAP at all.  As the descent goes along, the MAP will
increase so I reduce throttle as necessary to keep the MAP around 22 to 23
inches.  This puts the IAS at 180 plus or minus a little.  Now, as the descent
goes along, the EGT will start to climb so I increase the mixture slowly and
as necessary to keep the EGT somewhere close to the cruise number.  Early in
the descent my fuel is where I want it (header tank) and transfers off.  So,
when I am about three miles out from my airport or another uncontrolled
airport, I'm whistling along at about 180 to 190 knots IAS with the EGT still
hot, the MAP at 23 or so inches and the engine operating just fine, like
cooking.  I've monitored for traffic and announced my intentions so I make a
low approach over the runway (100 or so feet AGL) and, as traffic permits,
pull up and around to the downwind.  This kills the airspeed so I arrive prior
to the abeam near 110 knots IAS, so out come the wheels, below 100 knots half
flaps come down and around the corner we go. Arrivals at a controlled airport,
of course, require everything to be moved out a good bit to provide traffic
separation and get set up for going dirty in time for a straight in or an ILS
approach.  But engine management is the issue, and my point is that the engine
must be kept at work, in my opinion, all the way during the descent.  If that
is a problem then the descent must be started further out.  A long descent
near idle, cool engine, dump fuel in there, switch tanks, throw the wheels
out, some flap, then ask the engine to perform and the result might be some
complaining, or no performance at all.
 
 I hope we will get some definitive report as to why the engine on N320WH did
not respond.  If so, we will all learn something useful that we can apply to
our own building and/or operating procedures.
 
 George Shattuck
 N320GS
 Kit #393, 1989