"BDS" wrote in message
We've been having a problem with the engines on our Seneca II for awhile
now
and I wonder if anyone else has any experience with it. The engines are
TSIO-360s and if we lean at cruise with about 75% power (typically around
32-in MP) or less to anything over about 1400 EGT (which is still ROP),
the
manifold pressure will begin to drop off after awhile - sometimes after
only
5 minutes or so, sometimes after 30 minutes or more.

I would suspect that the turbocharger bearings are lightly coked up and
squeeze the shaft when they expand from heat. This can happen even with
proper operation and cool down.

D.