Kepi

Here is the response from my investigator after I told him what the person who claimed to be at the NTSB investigation said.

"I can tell you from all my years of doing this and looking at dozens of crashed PT6’s that if there is enough force on the engine to cause the entire power turbine wheel to shed all its blades, then it will happen to the compressor turbine wheel as well. They are fractions of an inch aware from each. And we would see it in the impeller and impeller shroud. He is right, that engine spins at 38,000 rpm. And when it comes to a screeching halt at that rpm under full power, all hell breaks loose. That engine was pristine other than the PT wheel. There was no foreign object damage from dirt ingestion as he says. You can see that in the entire compressor section. I attached photos of the first 2 stages of compression. The first is the impeller wheel and the second is labeled “#2” Where is this damage from engine running and ingesting dirt? It’s not there. Because this engine most likely shut down when the PT wheel failed. The torque wrinkle in the exhaust duct comes from a high powered prop hitting an inanimate object. It doesn’t care whether it is a tree or a house or dirt. When 800 hp at the propeller comes to a stop, the large rotating mass of the engine wants to keep going. As such it puts a big transverse wrinkle in the exhaust duct.

I did look at possible autopilot issues. I don’t buy he forgot to turn it on. I don’t buy that he got spatial disorientation. The flight track shows him flying straight and then just losing altitude. As he would if he lost engine power. I did look and the autopilot didn’t have a trim motor which is really the only unit in an autopilot that can generally kill you. The typical pitch and roll servos don’t really have a history of putting the aircraft in an unrecoverable situation. I didn’t have or test the autopilot computer but the evidence on the flight controls really isn’t there to support that theory."


QUOTE=JamesNoBrakes;2059739]We can't even get into the blade creep and micro fractures at the neck that would be present from blade failure. To be sure, there are signatures, but many would not be present to the naked eye. For comparison, Google a few ATSB or NTSB full accident reports. You'll see the kind of testing that goes along with a PT6 blade failure. I think the inference is that the engine turbine must have failed due to the intact compressor, but then there's nothing in front of the compressor anyway.

Are there any pictures of the centrifugal compressor? Burner assembly?[/QUOTE]