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Lycoming Loses Big Lawsuit / Indemnity Claim Squashed
("Gene Kearns" wrote)
the TIO-540 and LTIO-540 engines... http://tinyurl.com/65b9u (From the story) The case revolves around a number of small airplane engine failures that occurred when the airplanes' crankshafts broke in flight. Between 2000 and 2002, there were 24 failures and 12 deaths in Cessnas, Pipers and other airplanes with Lycoming aircraft engines. Interstate Southwest supplied Lycoming with the crankshaft forgings for those engines. Following the failures, Lycoming launched an investigation aimed at determining the cause. Its conclusion was that Interstate Southwest had overheated the forgings, weakening the steel. But attorneys for Interstate, Mr. Rose and Hal Walker of Rose Walker in Dallas, found a different cause. Their experts were able to determine that Lycoming's design for the crankshafts, which dates back to smaller, lower horsepower engines from 40 years ago, was inadequate for the larger, higher horsepower engines that failed. They also found that by adding Vanadium to the steel -- something Lycoming decided to do just before the failures began -- the company further limited the amount of stress the crankshafts could withstand. Lycoming had added Vanadium to make the steel harder and reduce the number of machining operations, ultimately saving the company money. Ultimately, jurors agreed with lawyers for Interstate, and found that even Lycoming's investigation of the crankshaft failures was fraudulent. "The jurors found the combination of poor design and Vanadium pushed these crankshafts beyond their limits," says Hal Walker. "That's why these planes crashed, and not, as Lycoming claimed, because Interstate overheated the forgings." Montblack |
#2
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A lot of highly stressed shafts etc (like in a transmission) are made of AISI 6150 steel which is probably similar to what Lycoming specified. I understood that Lycoming also nitrided their finished shafts, which should further increase the fatigue strength as well as provide an excellent wear surface on the journals. (The hinges of hell are nitrided.) As a Mech Engr I thought adding Vanadium did only good things to steel. I don't see how they could save any machining costs by adding vanadium. Surely they didn't add vanadium just so they could skip nitriding? It is interesting that it appears to be only the turbo models that are involved. I wonder what the condition of the harmonic damper assemblies and their associated pins and bushings etc was for each failure. I'll bet it is appealed..... I sure hope so at least. |
#3
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As a Mech Engr I thought adding Vanadium did only good things to
steel. I don't see how they could save any machining costs by adding vanadium. Surely they didn't add vanadium just so they could skip nitriding? As a mechanical engineer, what the hell do you know? I f you want to know how much Vanadium to add, ask a jury. Bill Hale |
#4
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"nrp" wrote in message oups.com... [...] It is interesting that it appears to be only the turbo models that are involved. I wonder what the condition of the harmonic damper assemblies and their associated pins and bushings etc was for each failure. I'll bet it is appealed..... I sure hope so at least. Betcha $100 to a nickel that the verdict will be appealed, and that the punitive damages part of the judgment is drastically reduced. The appellate courts of Texas are not plaintiff-friendly unless Texas is the plaintiff pushing to hurry death by lethal injection. On the issues of the crank failures this litigation is not over. Biggest damages will go to the estates of people killed, that is, if juries find that Lycoming and/or other parties are at fault. I make no judgments here, don't know the details, and take no sides; but the Founders argued that in a true democratic republic the petit jury is the Palladium of Liberty. See the _Federalist Papers_ for details. If you don't like jury decisions see your representative about a constitutional amendment. |
#5
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Gene Kearns - A designer really has his back to the stress wall if he has to use 4340/4350 steels. It doesn't make sense to compromise the fatigue capability for machinability in a part like this. Don't all the Lycomings from 100 hp thru the big 540s (or even 720s?) have the same OD on their crank and rod journals? I still wonder about the condition of the damper system(s). I'm sure Lycoming would have checked that out, but maybe a nasty service bulletin or AD will be coming? NRP |
#6
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What is interesting about this suit is it's not the estates suing. This is
case of corporate defamation. Textron Cessna Lycoming passed blame on to these guys for what is really their responsibility. I don't know how covering their collective arses affected the suits Lycoming by the estates, but I bet it pretty much closed down Interstate. Perhaps interstate screwed up, or maybe they did not. What's for sure as that Lycoming didn't test and inspect. There are almost always reduction settlements from what I hear, so either it will get appealed or settled. The insurance companies are big on settling anyway, and the interstate guys likely just want enough money to start over. "Gene Kearns" wrote in message ... the TIO-540 and LTIO-540 engines... http://tinyurl.com/65b9u -- Homepage http://myworkshop.idleplay.net/ |
#7
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Betcha $100 to a nickel that the verdict will be appealed, and that the punitive damages part of the judgment is drastically reduced. The appellate courts of Texas are not plaintiff-friendly unless Texas is the plaintiff pushing to hurry death by lethal injection. The Appellate structure in Texas is two tiered: Criminal (such as your death penalty appeals) takes one route and Civil (such as this case) takes a separate but parallel route. Something to keep in mind, is that the venue was in Anderson, Texas, the county seat of Grimes County, Texas and Interstate Forging's home county. Never heard of it? Most havent. Its small. The whole county was loosely populated enough to be covered by 3 ambulances (thats where my knowledge of their territory comes in). I've walked in the 100 year old courthouse in the past, where this trial was held. What I am getting at is, hometown company in a small county where everyone knows everyone else (literally) is likely to get a favorable jury when in a civil matter against the behemoth from out of town. So, yea, the punitive damages may get overturned but here's the nice thing. The trial, all of the metallurgy data, etc.. is now public record. Other experts can go over it. It may be introduced in other trials. If the engineering WAS (and probably IS) faulty, then its clear that one of several things will happen, the most favorable being the redesign of the cranks. In any event, the rotary auto engine I'm fitting right now just took a big increase in value in my eyes. (on a side note I dont intend to debate further, how is a 10+ year appeal process "hurrying to death" with lethal injection" The latest appeals have said the long wait amounted to cruel and unusual punishment.. isn't that a hoot) |
#8
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I don't think it would be the static HP that would be the problem. I get less than 5 KSI shear stress for a solid or near solid shaft transmitting 400 HP at 2700 RPM. A complex section like a crankshaft of 4340 heat treated, blessed by the Pope etc, and nitrided should be good for maybe +/- 40 to 50 KSI. Obviously the fatigue problem is completely dominated by the dynamics, which in turn are dominated by the damper integrity(s). Mechanics have to realize how important these gadgets are. I'd hate to have to explain to a jury how they work though. Another minor stress factor could be gyroscopic loads in an aerobatic A/C. Dunno.... guess we'll wait and see... Yep! NRP |
#9
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Sad thing is tht there was probably an engineer that said to his boss
"Sir, the crank is undersize for this increase in horsepower. We should up the diameter and change the crankcase accordingly". Management reply: "That would cost too much and marketing says we need this engine ready next month. No time or money for re-tooling or a new casting. Make it work" I hear this kind of warped logic all the time where I am now..... Bob |
#10
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wrote in message ups.com... Sad thing is tht there was probably an engineer that said to his boss "Sir, the crank is undersize for this increase in horsepower. We should up the diameter and change the crankcase accordingly". Management reply: "That would cost too much and marketing says we need this engine ready next month. No time or money for re-tooling or a new casting. Make it work" I hear this kind of warped logic all the time where I am now..... Hmmm...Colin Kingsbury (in this group) says that sort of thing is common in software development and infers that it's a _good thing_. |
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