Lycoming Mandatory SB (crankshaft, again, and more of 'em)

[jarhead]

Originally Posted by Mike S

If I understand the problem, it had to do with the metallurgy of the cranks, not the design.
__________________
Randy

Sorry Randy, the REAL problem is LAWYERS and LAWSUITS.

Mike

The actual problem was improper heat treatment by the foundry that forged the crankshafts to Lycoming's specifications. That problem was made 100 times worse once the lawyers for folks who suffered engine failures got involved... So you're both right.

[rv6ejguy]

Originally Posted by jarhead

The actual problem was improper heat treatment by the foundry that forged the crankshafts to Lycoming's specifications. That problem was made 100 times worse once the lawyers for folks who suffered engine failures got involved... So you're both right.

Well if you can believe what you read and relate it to which crank problem you are talking about, you can make something out of the murk possibly. The biggest and latest one was related to the addition of vanadium to the material mix at Lycos request despite the concerns of the forging company and not heat treatment. Lyco lost the first round of lawsuits over this. There have been other issues in the past with crank gear pressing causing cracks (new process) and other issues related to improper heat treatment a few years back on a smaller number of six cylinder cranks. There was a class action suit filed by a Piper group a few years ago after a large number of catastrophic engine failures and some deaths and the utter inability of these engines even making it to 1/4 their stated TBO.

The the older manufacture Lycos appear to be a much more reliable than some of their later offerings and it seems to be exactly that quality went downhill when major component outsourcing started. It seems that some of the new manufacturing processes are very different from the original ones when the engines were first certificated. It's clear that inadequate testing and QC was being done to validate these new processes prior to release of the product to the public. A new piece of paper submitted to the FAA outlining design or process changes does not validate a design or process change.

The last 6 years or so have been very rough on Lyco. We are probably lucky that they just don't fold up the tent as some of the court awards have been staggering.

I'm afraid I can't lay the blame for a Lyco's high cost at the foot of the lawyers. If Lyco had done a proper job of things as they seemed to be doing 10-20 years ago, they'd have a lot less problems.

[jarhead]

Originally Posted by rv6ejguy

The biggest and latest one was related to the addition of vanadium to the material mix at Lycos request despite the concerns of the forging company and not heat treatment.
...

The the older manufacture Lycos appear to be a much more reliable than some of their later offerings and it seems to be exactly that quality went downhill when major component outsourcing started. It seems that some of the new manufacturing processes are very different from the original ones when the engines were first certificated. It's clear that inadequate testing and QC was being done to validate these new processes prior to release of the product to the public. A new piece of paper submitted to the FAA outlining design or process changes does not validate a design or process change.

Ahhh, gotcha: open mouth, insert foot. Boy that's a familiar taste...

Based on what you're saying in the 2nd quoted paragraph, it seems the Feds have a bit of responsibility here too. If Lyco goes to them with process "improvements" and FAA just accepts them at face value, and those "improvements" turn around and start biting people's a**es down the road, seems to me the FAA should be answering to the lawyers and families as well. But we all know the odds of that happening... I'm not holding my breath.

[tacchi88]

Here are a few notes on crankshafts. SBs are not mandatory, although it may sometimes be the first step towards an AD which is indeed mandatory. Service limits of a crankshaft or any other component in these engines is often misinterpreted. A "serviceable" crank used which is on far end scale of
limits is not a good crank to reinstall with new bearing. Stop and think, the engine will be reassembled with built it wear already in place. In the end, it will never see a second OH, and cause further damages, such as crankcase fretting, and in every case, will wear the new, overpriced bearing considerably faster.
Most of us, myself included, despises the FAA interference, however, there are rules that make sense. One is terminology and practice. The FAA does not recognize the term remanufactured. There only teo terms with regards to repairing an engine or any component. They are overhauled and rebuilt.
The process of repairing is the same. remove, clean inspect each compenent in accordance with accepted practices, make any repairs necesary and reassemble. The difference is that in an overhaul, components are to be within "limits", whereas a rebuilt must be assembled with compenents within "new tolerance". In the case of "rebuilt", in most cases it would require new parts, such as cylinders, due to cost. Cheapre nowadays to install new that to "rebuild".
In general. metalurgy in AC engines is abismal, archaic and generally no where near given the inspections we are led to believe. We can't be having crankshaft ADs year after year, if the damned things were made properly in the first place. How many crankshaft ADs are found in the auto world?
The biggest problem is the bearacracy, with draconian rules, tort laws, and generally manufacturers that have a captive market. They can experimenr, and our expense. Note, they screw up, we pay. Even the aftermarket guys weill pay for their mistakes. Case in point ECI cylinders.
And so it goes.
A crankshaft for a high powered auto race engine able to whitstand punishment unheard of in aviation are being manufactured for a fraction of the cost of even a used AV crank. Then again, the auto industry has competition, treputations to uphold, and no beauracracy.
Everytime this subject comes up, I have to vent. Sorry if it takes up time.
T88
RV10
A&P/IA/EAA Tech. Advisor,