<<So, does everyone agree that induction icing, more specifically, air
filter
icing was the likely culprit?  If so, why doesn't this happen more often,
since air filters are universal, and some, like Cessna, are right in front
in
the open?  Could it be an installation problem in my case?
Ed de Chazal (N361DC)>>

Your trip reads like a carbon copy of one of mine, except I was flying a
spam can (C-TR182).  It is carbureted and has the air filter on the left
side fed by a NACA duct.  I was climbing up to 17,000 to get out of some
mixed rain and snow with a little icing and I almost got to the top when the
engine started to surge and lose power.  The first thing I thought of was
the recently-welded exhaust system and the turbo was losing boost because of
a broken pipe.  I throttled back and it ran okay, made an instrument
approach to the nearest airport (takes a long time to get down from 17,000
when you're in a hurry).  Nothing wrong, of course, but I did my diagnosis
on the ramp getting rained on compared to your dry hanger.  What I didn't
think of was carburetor "heat."  Even though the engine was carbureted in
all the time I flew it there never was a trace of carburetor ice because the
inlet air was always heated by the turbo.  I knew the carb wasn't icing
because the carb temp was high, but it didn't occur to me that the carb heat
control was also an "alternate air" source and the problem was a plugged air
filter.  My current Cardinal and my ES under construction both have a
spring-loaded alternate air door.  It would seem like a good idea to make
the ram-induction valve be configured in the same way, for EITHER manual or
automatic action.  In my case, any time I can take the requirement for an
accurate decision away from the dufus behind the wheel (or beside the stick)
it is a good thing.

Gary Casey
ES #157