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In a message dated 1/20/2002 3:44:32 PM Pacific Standard Time, gwbraly@gami.com writes:
<<<...Agree with all of that, except the IO-550 crankshaft has been operated in
the 500 to 600 HP range already...>>>
Well, now, there's a meaningful bit of information. Anyone out there ever heard of Fatigue Cycles? For example, I have an SBC-style crankshaft which has been OPERATED at over 1000 HP (for less than one hour). Is it broken? NO. Is it cracked? NO. Is there a realistic expectation that it would continue to live (1000 more hours) at 500 HP? NO again.
I also have an SBC-style crank which BROKE in less than 10 hours at 500 HP (4600 RPM) from fatigue caused by a torsional vibration engineering problem. The fact that a crank has "OPERATED" at some level yields absolutely no useful information, especially with regard to operation in an aircraft, which presumes the expectation of a given level of safety. (I say "presumes" because, in view of some of the stuff I see being installed on experimentals, it is more than clear that some builders have no such realistic expectation.)
But gosh, Continental crankshafts are world-renowned for their reliability. Let's see. It seems to me that it wasn't all that long ago that there was a very expensive AD under which 520 crankshafts made from NON-VAR (vacuum-arc-remelt) steel had to be discarded and replaced with "NEW, IMPROVED" cranks made from VAR steel. And then, can you imagine, subsequent field data revealed there wasn't a statistically significant difference in the failure rate of VAR vs. NON-VAR crankshafts? And wasn't it because of the ridiculous failure rate of TSIO-520 bottom-ends in the Malibu that Piper ceased production of the Malibu, replaced the Continental with a Lycoming and called it a new airplane ("Mirage")?
And what do you think Charlie Kohler's opinion of the engineering magnificence of a Continental crankshaft is????? (Also, in an analysis typical of Continental, they blamed someone else for the problem. DUUUHHHHH, WE TINK IT BROKE CUZ OF DA NITRIDING!!!.)
Then, if you can, get some inside info from Continental about the expected life of the hopped-up engines which the Lancair Factory used at Reno.
Try to keep in mind that Logic and Facts usually beat Intuition and Wishful Thinking.
Jack Kane
EPI, Inc.
LML website: http://members.olsusa.com/mkaye/maillist.html
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