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indigoonlatigo(at)msn.com
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 Posted: Wed Mar 15, 2006 9:42 am Post subject: Lycoming question? |
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A question from a not so well read builder...I know it happened, but I never
learned of the reason why those crankshafts on the Lycomings had bent.
After so many years of producing these engines without problems, why did it
happen.
Also, thank you Kelly M for your great email discussing the differences
between rebuilds and overhauls. I did no know that Lyco had sourced out the
production of their parts.
Is it normal to have a lot of anxiety about buying an aircraft engine which
almost cost what houses used to cost and then having to buy one half the
houses again in a few years?
Also, will these engines be able to burn 91 octane or is there a compression
specification that needs to be orderred with the engine.
Sorry in advance, I am sure I am going to get thrashed on this post.
Too much time between patients.
DO Not Archive
John G.
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johnwcox(at)pacificnw.com
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| Posted: Wed Mar 15, 2006 10:26 am Post subject: Lycoming question? |
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I will look for the copy of the final decision to clarify the point.
Think it was back in August. As I remember the suit. Lycoming sued
their manufacturer/supplier of choice for production of OEM crankshafts.
Lycoming required a post machining, hardness finish which the vendor
stated would not work. Crankshafts failed, people died, Lycoming sued
their supplier. The defendant (crankshaft maker)won relief, Texas
jurors did not understand the technology, the settlement was almost in
the 3 digit millions... 89 as I remember. It is under appeal. No
kidding!
Life is always about trade-offs. Lycoming is passing the learning
experience on to those who use these cranks. The FAA is dealing with the
issue with a series of Service Bulletins affecting a large mass of
Lycoming owners.
George Braly of GAMI makes a living of teaching pilots how to caress
their internal combustion aircraft engines. His Prism system once FAA
approved should be a big step. Running LOP is another. Lycoming has
the advantage of sodium filled valves which are not present on TCMs.
They are a good company, quality product.... know the tradeoffs. "Don't
Hot Rod".
John $00.02
Do not Archive
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rvbuilder(at)sausen.net
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| Posted: Wed Mar 15, 2006 10:27 am Post subject: Lycoming question? |
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Depending on who you ask, Textron or their subcontractor that made the cranks, they were either not made to spec or the formula for the metallurgy was changed. Either way we got screwed. Glade the FAA's PMA and process for certification protects us so well.
Running the 8.5:1 pistons and a carb you can probably get away with Mogas. I wouldn't do it with injected or high compression.
Michael Sausen
RV-10 #352 Working on Fuselage
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Kellym
Joined: 10 Jan 2006
Posts: 1700
Location: Sun Lakes AZ
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| Posted: Wed Mar 15, 2006 11:08 am Post subject: Lycoming question? |
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A few points. The Texas jury undoubtedly was presented as much
technology as both sides chose to present. Whether they understood it
or not is probably irrelevant, they believed the defense side. IIRC, it
was Lycoming that changed the actual alloy content of their specs, and
that the same supplier had made cranks for them previously with no
problem. Lycoming alleged that the heat treatment was improper, the
defendent convinced the jury the alloy specs were at fault.
Lycoming, however, paid for all the 6 cylinder crankshaft replacements,
while they are only offering $2K towards the 4 cylinder crankshaft
replacements.
I'd say they "were" a good company. Today, I expect they are dominated
by their corporate conglomerate management. Their 4 cylinder engines
from the 90s have a really bad history of cam and lifter failures at
mid-TBO or less.
Please explain the sodium valve advantage. The only two differences are
that more heat is transferred to the valve guide, rather than passing
the heat through the valve seat, and being hollow the valve stem is
weaker. It is Lycoming that requires the SB388 for valve wobble and
sticking valves. On some of their turbocharged engines they had to
retrofit oil cooling to the valve guides to make them live. I don't
know if they have ever solved the low engine life on the Piper Mirages.
Only the low power continentals seem to have valve problems...not that
they don't have their own other issues. JMHO
KM
A&P
DO NOT ARCHIVE
Quoting "John W. Cox" <johnwcox(at)pacificnw.com>:
| Quote: |
I will look for the copy of the final decision to clarify the point.
Think it was back in August. As I remember the suit. Lycoming sued
their manufacturer/supplier of choice for production of OEM crankshafts.
Lycoming required a post machining, hardness finish which the vendor
stated would not work. Crankshafts failed, people died, Lycoming sued
their supplier. The defendant (crankshaft maker)won relief, Texas
jurors did not understand the technology, the settlement was almost in
the 3 digit millions... 89 as I remember. It is under appeal. No
kidding!
Life is always about trade-offs. Lycoming is passing the learning
experience on to those who use these cranks. The FAA is dealing with the
issue with a series of Service Bulletins affecting a large mass of
Lycoming owners.
George Braly of GAMI makes a living of teaching pilots how to caress
their internal combustion aircraft engines. His Prism system once FAA
approved should be a big step. Running LOP is another. Lycoming has
the advantage of sodium filled valves which are not present on TCMs.
They are a good company, quality product.... know the tradeoffs. "Don't
Hot Rod".
John $00.02
Do not Archive
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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
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bsponcil(at)belinblank.or
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| Posted: Wed Mar 15, 2006 3:08 pm Post subject: Lycoming question? |
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The 0-540-B4B5 235HP has 7.20:1 compression pistons and can be STC'd for
burning 80/87 octane auto-gas in most of the certified world with just a
placard and a 337. Still, vapor lock is the main trouble (pneumatic lock as
well) with running autofuel and that's a function of the entire system
rather than just the compression of the pistons.
I know EAA/Petersen had lots of trouble with the Mooneys and Comanches due
to autofuel boiling in the carb and thus never produced an STC for them.
That's not to say that our RV-10s would suffer the same problems, but I'm
told that the higher performance the higher the risk of vapor/pneumatic lock
when running autogas.
-Brian
#40497
N211BD
Iowa City, IA
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