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CloudCraft(at)aol.com Guest
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Posted: Tue May 23, 2006 9:35 am Post subject: Advice from Gear-Heads... LOP |
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In a message dated 23-May-06 10:00:19 Pacific Daylight Time, n395v(at)hughes.net
writes:
At the risk of generating spirited debate and controversy here is something
for you big bore turboed gear heads to consider.
[/img]
I have never been a proponent of LOP solely for fuel savings but given $4/gal
is probably here to stay it has moved up on my list of reasons to operate LOP.
<><><><><><><><><>
Dr. Milt, you're a muck raker!
I was (and in theory still am) a LOP guy but it was an interview I did last
millennium with Suburban Air Freight of Omaha, Nebraska -- an AC-680-FL fleet
operator -- who changed my mind.
Their reason for running ROP was not about cylinder head temperature nor any
of the usual heat or oil wash reasons: it was because of the low lead content
in modern AvGas.
They saw a problem with valve guide lubrication that lead was intended to
provide in these engines.
So, in the controversial spirit of cheapness, how much is one saving LOP vs.
other engine wear costs?
I don't know the answer and I think it depends on how many hours a year one
operates. A recreational operator with one airplane has a different economic
urge than a fleet operator who is trying to make money by flying a bunch of
airplanes.
Wing Commander Gordon
Life is not simple anywhere. Probably less so elsewhere.
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BobsV35B(at)aol.com Guest
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Posted: Tue May 23, 2006 10:27 am Post subject: Advice from Gear-Heads... LOP |
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Good Afternoon Commander Gordon,
My understanding is that the FAA ran some tests of leaded against non leaded
fuel. Rumor has it that it was some model of Aero Commander, but I do not
know which one.
In any case, one engine was ran on leaded fuel and the other on nonleaded
fuel. The only difference at overhaul time was that the engine that was run on
nonleaded fuel was a lot cleaner. There was no measurable difference in
wear.
There are just as many engine experts who will tell you that the idea of
lead being needed by any of our engines to lubricate the valves, or anything
else, is pure unadulterated rubbish, as there are ones who swear the lead is
needed.
The FAA may not have said it in just those words, but it was pretty strong
statement.
Most of the folks who claim the engine needs the lead tend to be old time
mechanics and engine rebuilders rather than trained engineers.
Do you know of any scientific evaluation that shows things differently than
did the FAA tests?
I once read an article by a gentleman who claimed to be the engineer who
developed Ethyl gasoline. It was his statement that the lead was a necessary
evil to get the octane up at low cost. It did nothing for the engine other than
change the octane and it was detrimental other than that.
If anyone is interested in reading one pilot's take on engine operations,
they might want to check through John Deakin's article for his series on engine
management.
Try: _http://www.avweb.com/news/columns/182146-1.html_
(http://www.avweb.com/news/columns/182146-1.html)
Happy Skies,
Old Bob
AKA
Bob Siegfried
Ancient Aviator
Stearman N3977A
Brookeridge Air Park LL22
Downers Grove, IL 60516
630 985-8503
In a message dated 5/23/2006 12:38:26 P.M. Central Standard Time,
CloudCraft(at)aol.com writes:
Their reason for running ROP was not about cylinder head temperature nor any
of the usual heat or oil wash reasons: it was because of the low lead
content
in modern AvGas.
They saw a problem with valve guide lubrication that lead was intended to
provide in these engines.
So, in the controversial spirit of cheapness, how much is one saving LOP vs.
other engine wear costs?
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CloudCraft(at)aol.com Guest
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Posted: Tue May 23, 2006 11:00 am Post subject: Advice from Gear-Heads... LOP |
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In a message dated 23-May-06 11:27:46 Pacific Daylight Time, BobsV35B(at)aol.com
writes:
Most of the folks who claim the engine needs the lead tend to be old time
mechanics and engine rebuilders rather than trained engineers.
Do you know of any scientific evaluation that shows things differently than
did the FAA tests?
<><><><><><><><><>
Old Bob,
As a friend of mine, since gone West, used to say, "It's either very loose
science or very tight magic."
The only science these guys had was operational experience on a fleet of
Lycoming IGSO-540s over a long period of time, and their opinion on what kept the
engines on the airplane and not in the shop.
Their valve guide problems could have been something else entirely, but they
had their belief in what caused and fixed it.
The man I interviewed was Jay Armstrong (Jay Armstrong at 402-344-4100) and I
just called him to make sure I either didn't misquote him or if he's changed
his mind since 1999, but he's not in today.
Rats!
Wing Commander Gordon
Life is not simple anywhere. Probably less so elsewhere.
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barry.collman(at)air-brit Guest
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Posted: Tue May 23, 2006 11:15 am Post subject: Advice from Gear-Heads... LOP |
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Hi All,
The FAA did indeed run some tests of leaded against non-leaded fuel.
They were conducted, although I cannot say if it was exclusively, using their
Aero Commander 680E, s/n 818-62, N50, in 1999.
Very Best Regards,
Barry C.
---
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BillLeff1(at)aol.com Guest
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Posted: Tue May 23, 2006 12:14 pm Post subject: Advice from Gear-Heads... LOP |
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Charles F. Kettering (of Dayton Ohio) invented the use of Tetra Ethyl Lead
in gasoline. He is long dead!
Bill Leff
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BillLeff1(at)aol.com Guest
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Posted: Tue May 23, 2006 12:25 pm Post subject: Advice from Gear-Heads... LOP |
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I have been flying and maintaining IGSO-540's in Commanders since 1970. The
only thing that keeps cylinders from failing is 50GPH at cuise! That
generally works out to 50 deg. ROP.
Heat is the issue. I do not have the same problem on my 560F with IGO-540's.
I have been flying that specific airplane since 1973.
Bill Leff
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