PerfInit

Maybe perhaps because the kid actually got it in the air and flew around? If one smokes a PT-6 on start, would it be possible to expect the power turbine or other parts of the hot section could incur permanent damage and perhaps not be able to drive the prop gearbox very well (or for very long)?? Go ahead John, tell me where I am wrong, I know you will anyway.

JohnBurke

Yes, it's very possible to operate a PT6A, and most any other turbine engine, after a hot start. It happens with some frequency. You don't understand this?

Do you understand how a PT6A works? You understand it's a free turbine? You understand that the turbine which drives the prop isn't attached to the rest of the mechanically, except by housing, right?

What's required when an engine experiences a hot start? Do you know?

An inspection. A boroscope inspection, typically done through the ignitor holes. There may be no damage at all, and the tolerances depend on the temperatures reached, and the duration. A hot start isn't a death sentence, and PT6's are more tolerant than you may think of improper start procedure, including early fuel reduction or fuel introduction at low engine speeds.

When an engine is started hot, if it keeps operating, there's a very high probability that it will keep operating, quite possibly for years if fed fuel and oil, without incident. Given the reverse flow nature of the engine and its design, it tends to be a very resiliant powerplant.

The typical effect of a hot start, depending on temperature and duration, is blade erosion, and repeated high thermal cycles can lead to fracturing in the can (normal) guide van damage, and eventually failure of the blades in degrees that might range from deformation to stretch or creep, imbalance, cracking, or loss of blade portions. Historically this is not something frequently seen following a hot start, and you might be surprised how often hot starts go unreported.

If the kid got a hot start during his engine starts, and it hasn't been reported that he did, it's very possible to go operate that aircraft without a failure. If indeed he did get a hot start on one or both engines, clearly the engines did operate for some time.

Go figure.

You were saying?

ShyGuy

Any landing you can walk away from is a good landing.



Any landing you can walk away from AND use the airplane again is a great landing!

ShyGuy

Ha! That is funny