Diesel aircraft engines and are the light jets pushing out the twins?

"Peter Duniho" wrote in message
...
"Paul Sengupta" wrote in message
...
Turbines do suffer from manufacturing defects (if I recall, there was
an
uncontained failure in the 90's on some rear-engine jet -- 727, DC-9 or
something like that -- where the blade failure was due to some
metallurgical
problem).

Sioux City DC10.

Not actually the accident I'm thinking of. But yes, that's another
example
of blade failure (did they eventually determine it was a manufacturing
defect, or a maintenance problem?).

They say it was a manufacturing defect about the size of a grain of
sand.

http://www.ntsb.gov/speeches/former/hall/jh970912.htm

"Metallurgical examination of the titanium fan hub revealed that a fatigue
crack originated from an inclusion near the surface of the hub's bore. The
inclusion had been formed during the titanium vacuum-melting process at the
time of manufacture about 2 decades earlier, which developed an internal
cavity during final machining and/or shot peening. At the time of
manufacture, the fan hub had been ultrasonic and macroetch inspected."

The accident to which I was referring only involved one or two fatalities,
of a passenger or of passengers sitting right next to the engine.

Yes, I know the one you're talking about.

It's mentioned on the page referenced above:
"We will soon conclude our investigation on that Delta Air Lines MD-88
engine failure I mentioned earlier. Metallurgical examination of the
fracture surface of that fan hub revealed that a fatigue crack had
originated from a machining defect in a tie rod hole. Further, the fan hub
had been fluorescent particle inspected only seven months before the
failure, when the crack was estimated to be approximately ½-inch long."

Also http://www.ntsb.gov/pressrel/1998/980113d.htm

Paul

"Peter Duniho" writes:


Not actually the accident I'm thinking of. But yes, that's another example
of blade failure (did they eventually determine it was a manufacturing
defect, or a maintenance problem?).

The accident to which I was referring only involved one or two fatalities,
of a passenger or of passengers sitting right next to the engine.


I recall it as well. DC-9, I believe...

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"Peter Duniho" wrote in message
...
Turbines do suffer from manufacturing defects

http://www.tc.faa.gov/its/cmd/visito...30/turbine.pdf

"Peter Duniho" wrote in message
...
"Mike Rapoport" wrote in message
nk.net...
I don's see that I've overlooked something relative to the Caravan. The
Caravan has a 940hp engine. There is currently no suitable piston engine
to
power such a large, single engine airplane. It couldn't be anything
other
than a turbine.

As you yourself pointed out, that 940hp engine is derated to 675hp. You
don't need a 940hp piston engine to provide the equivalent power, and a
675hp piston engine is not out of the question (for example, the Orenda V8
turbine replacement engines are in that ballpark, if I recall correctly).

Large snip.

I agree that it is difficult to compare different types of engines apples to
apples since the power and specific fuel consumption curves are so
different.. I have two airplanes, one turbine and one piston. Both engines
are well suited for their applications. In the Helio, power is often set to
15"MP to keep the speed down in turbulent, low altitude mountain flying. A
turbine would be horribly inefficient operated like this. In the MU-2,
power is set close to the torque or temp limits from takeoff until reaching
about 16,000' on the descent. A piston engine operated flat out like this
wouldn't last long, particularly at high altitude. Both powerplanes have
their place although I think that diesels will eventually replace gasoline
piston engines because of their efficiency, long life and simplicity.

Mike
MU-2