Lycoming SB for soft pin plugs

On Fri, 17 Aug 2007 23:59:42 -0000, "Robert M. Gary"
wrote:


The shop is recommending pulling all cylinders and doing a top. Does
one cylinder having an issue with pin plugs mean others much (the IA
says so, I'm not sure). I'm thinking I just want to replace this
cylinder and then fly it. The oil analysis will show if there is
another plug wearing.

One cylinder having pin plugs issues really doesn't mean a thing with
regard to pin plugs in the other cylinders. However @1000 hrs, it's
very likely that the e-valve guides in all the cylinders are at or
beyond serviceable limits.

Am curious what the OP or his tech found that requires cylinder
replacement.

The IA said the cylinder was "2 one thousands" out of spec. Actually
one of the reasons we choose this cylinder to pull ( from the oil
analysis we knew we had to pull one of them do to progressively higher
AL counts), was that the cross hatching was gone on #1 (this is recent
because we boroscoped it at annual and didn't see this).
This engine has 1000 SFNEW in 1998 so I was not expecting to have to
replace cylinders. The IA did say that the bottom looks like a new
engine, no sign of any problems down there (we change the oil about
every 30 hours).
Anyway, the IA is recommending a full top and I'm not sure that is the
way to go.

-Robert

A lot if it depends on the installation, as in how much stuff has to
get yanked off to get at the "one" cylinder.

Theshop labor cost for one should not be 1/2 of the labor cost to do
2, or 1/4 of the labor cost for 4. R/R'ing the cylinders is the easy
part. Getting all the other stuff out of the way and back on is what
takes the time...

I would definitely have the two on that side of the engine sent out
for " inspection and repair as needed". If the one that you have off
already needs to go to an oversized piston, then it's twin on the
other side should be punched out also. If you are just going to bolt
on a new one, that is not an issue.

Been a few years since I shopped for cylinders/repairs. A set of
guides, and e-valve and a ring set/hone job used to be relatively
inexpensive. If you have to purchase a piston and have the cylinder
bored oversize, you might be getting to where a new replacement is
more economical.

TC

I have taken the opposite tack... On a 1500 hour 0-320 that is burning
a quart every 2.7 hours I have purchased 4 factory new Lycoming
cylinder kits... Come annual time (January, when the flying is bad up
here) we will pull the old cylinders and inspect the cam and pull one
rod bearing to check for wear... If all looks OK then we will just
replace the cylinders and call it good for another 1000 hours, or
so... If any of the bottom components look bad then we will overhaul
the bottom...

denny