REFLECTOR:LOP Ops

[Scott Baker]

Many of you have read John Deakin's "Pelican's Perch" articles in Avweb.com
regarding the subject of LOP (Lean of Peak) operations.  For those who have
missed these excellent articles, you can find them at the following links:
http://www.avweb.com/news/columns/182084-1.html
http://www.avweb.com/news/columns/182131-1.html
http://www.avweb.com/news/columns/182135-1.html
Just to throw in some additional information ... Continental's FADEC system
has two automatic mixture operating modes - Power and Economy.  The FADEC
system controls the fuel injection to each cylinder.  In the Power mode, it
meters the fuel-air mixture to obtain 100 degrees Rich of peak.  In the
Economy mode (69% power or below), the FADEC system meters the fuel-air
mixture to 100 degrees Lean of peak.
Aerosance (the designers of the Teledyne-Continental FADEC system) says that
the FADEC system does such a great job of running Continental engines Lean
of peak, that Continental may be increasing the recommended TBO in the near
future as a result.
I questioned the folks at Aerosance about the machine v. human element at
managing Lean of Peak operations.  They (perhaps with a degree of bias)
reported that the "good" fuel-air mixture range is quite narrow when running
Lean of Peak - meaning that a little mixture control movement (rich or lean)
will create significant changes in EGT's ...which calls for the human to
keep a close eye on EGT's to keep temperatures at the desired level.
Aerosance says that humans often forget to enrich the mixture during
descents, which may cause an overly lean situation, and which may cause the
engine some damage if the over lean situation is ignored.  They use this
argument to say that the FADEC, which keeps on eye on things and atomically
adjusts mixture during all phases of flight, is the better way to go and
avoids harmful overly lean engine situations.  Sounds like a good sales
pitch to me.  (I liked it!)
Duane Swing is a staunch advocate of LOP ops - especially with Lycoming
6-cylinder engines.
I confess that over the years I've listened to the folks at Lycon in
Visalia, California (who did the last overhaul on the C210 that I owned at
the time).  Lycon preaches going no further than 100 degrees Rich of peak,
reportedly because of the poor quality of av-fuel these days (apparently
octane ratings change from batch to batch at the fuel pump - even though
av-fuel is sold as 100LL - so says Lycon).  To keep the reman engine in
warranty, I burned a LOT of gas!  I've experimented with LOP ops, but not to
the degree that the diehards like Duane and others have.
Scott B.


----- Original Message ----- 
From: <RJohn15183@aol.com>
To: <reflector@tvbf.org>
Sent: Thursday, December 18, 2003 5:09 PM
Subject: Re: REFLECTOR:Lyc injection


>... I go faster AND burn less fuel AND keep my engine cooler AND keep it
cleaner.
>
> I never try to talk anyone into LOP ops but the ONLY logical reason
suporting by the data not to do it is just because you don't feel like
dinking with it.
>
> Rob