Today I flew from San Diego to Brownville Texas to attend a formation flying clinic.  After 6 hours of WOT flight I was descending through 5000' (down from 15.5k) an just a few miles from the airport when I had a sudden and sickening drop in manifold pressure.   The engine was still running fine, and I had plenty of altitude to make the runway, so I continued on debating weather or not to flip the turbo oil shutoff switch.  I had grown to respect this turbo so much that I finally decided that I had just blown out a fitting somewhere in the intake system downstream of the turbo.  I even continued on to a low pass for show rather than just landing.  When I eventually had time to take off the cowl I was dissapointed to find that all the fitting were in place and that the compressor wheel turns only with significant resistance.

So the turbo is dead, and I am out of the formation clinic and will have to decide tomorrow about flying home with a dead turbo.  Will maybe be able to take a look in the hot side and see what I see.

This turbo was the TO4 hybrid with a fixed wide open waste gate.  It had 130 hrs of mostly hard duty.  Sigh.

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David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net