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Message
Of course it was the exhaust side that died. I just wasn't thinking.
A real good method to reduce your risk is to assume every failure will
happen to you. Once you make that assumption, the next step is to make
your engine insensitive to the failure. So, a screen at exhaust header would be
a good example. We know it wouldn't last, but the concept is valuable. Perhaps a
little dip in your exhaust manifold would be enough to slow down the debris.
Just a little bend in the tubing might be enough. Moving the turbo further from
the exhaust port. Every inch reduces risk. It's not going to take much of a
change to reduce your risk to near zero.
Only after you've give thought to reducing the EFFECT of the failure, do
you consider ways to prevent the failure. So for John, sounds like going to
larger turbo will keep the rpm below failure zone. That's his preventive action.
I"m considering that and measuring turbo rpm dynamically. Not sure if I can do
it. But it would give me huge advance notice of turbo problem.
So if you both take action to prevent fault, AND action to reduce the
effect, you've got good system.
For my plane, I'm going to assume every thing that happened to John
will happen to me. I don't plan on allowing myself to say stuff like "that's
because it's a rotary". That serves little purpose. So I place great value in
his and other peoples reports.
Sure appreciate all the suggestions. Between the private postings and list
postings I've got quite a list of action items now. I'll post it here if you
guys interested.
Yea, I'm starting to remember something about this
now, as I was quite surprised at the time that the fragment from the exhaust
turbine had gone back up into the engine. An intercooler won't help you there
and a screen isn't possible either. But really what are the odds that this
would happen (I mean for anyone other than John" Turbo Killer" Slade)? Was
this just an anomaly or is this a common failure. Some of you follow some of
the rotary auto racing lists, have you heard of this type of failure
before?
I guess what I'm asking is this something us turbo guy's
should worry about and if so is there anything we can do about
it?
Todd (need to turn off the Olympics and get back to
building my shop)
As for
strainers, I don't believe John's blown turbo had any damage on the
compressor side. IIRC, he believes the turbine side somehow through a
piece back into the engine. I'm confident that he'll correct me
if I got that wrong :-)
Which turbo are we talking about?
The second turbo sent turbine fragments back into the exhaust port
and took out an apex seal.
This cost me a housing, a set of seals and a drive to North
Carolina.
I'm pretty confident that there was no engine damage from this
current failure where a turbine blade broke off.
Yes, I do have an intercooler.
John (off to install the big one)
-al wick
Artificial intelligence in
cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on
engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk
assessment, Glass panel design
info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
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