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Date: Tue, 20 Mar 2012 08:18:08 -0400
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Subject: Re: [LML] Top End Overhaul (TSIO550E) at 440 hrs TT (LIVP)
From: Colyn Case <colyncase@earthlink.net>
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Jeff,

Sorry to hear of these issues.  Thanks for sharing the information.  =20

The conclusion I came to was that you have to take a brand new engine to =
a good custom shop to finish the job.   I assume you are doing something =
this time to match up guides, seats, valves?

On the moisture issue, almost everybody says continentals make water.   =
Most are happy to leave the oil cap off.   Some add cam-guard.   I went =
further and put a air-wolf air/oil sep fed by the vac pump to bring the =
temp in the separator above 212 dF.   The theory is that this will blow =
the water vapor overboard in flight.      My theory is that most air/oil =
separators aggravate the moisture problem.    I don't have this setup =
flying yet so can't report results.

Colyn

On Mar 19, 2012, at 3:17 AM, Jeffrey Liegner, MD wrote:

Lancair Friends,

During my annual inspection, I found six cylinders with low compressions =
(20-30 over 80).  Yes, Master Orifice and all the right techniques.  We =
should know by now that BORESCOPE is the important step, and this was =
done.  Exhaust valve seats were eroded and pitted, causing leakage.  =
Valve face had mild thermal changes and stems were good.  A repair was =
planned.

Cylinders were pulled and inspected, confirming exhaust valve seats were =
the problem, and replacements were planned.  Further inspection showed =
some mild corrosion on some rods, wrist pins, even the cylinder barrels. =
 Evidence of moisture in the oil was apparent (more on this below).  I =
decided I would get the ECI Nickel+Carbide coating (CermiNil process).  =
The turn around time would have been four weeks minimum plus further =
reassembly and shipping, or I could get ready to go refurb'd compete =
cylinders, already coated and reassembled, immediately.  Hence, a =
complete Top End Overhaul.

Discussions regarding why this 2006 fast build TCM engine (flying since =
2007, now out of warranty) was having this problem revealed several =
illuminating tidbits.  One custom engine shop said "those cylinders are =
doomed from the first time you run the engine."  Others explained that =
these engines are assembled with factory-style production, not custom =
production, and so parts are placed and efficiencies taken to improve =
production.  Another explained that the valve seats are pre-reamed =
rather than post-reamed after installation, creating an opportunity for =
poor interaction with the valve edge, malposition and wobble, leading to =
early failure.  This appears to be a common issue for the engines around =
my 2006 era.  It's not confirmed, but there is rumor that their practice =
of using pre-reamed guides ended after they finished using up their =
inventory in late 2007.

The moisture in the engine is presumed to come from the hanger's =
humidity, a result of poor pitch of the asphalt, seepage under the =
hanger door/edges, trapped moisture inside the hanger.  I fly once or =
twice a week, oil gets to 200*F typically before I open the oil door).  =
I have not opened and vented the oil filler cap after flight (and I will =
now).  I may add a dehumidifier in the hanger, and/or engine dessicator =
(ex, from Tempest) (comments welcomed).  I will see about moving hangers =
or more effectively sealing the perimeter of my hanger floor.  Other =
ideas are welcomed.

I have Chelton and full engine monitoring.  The engine's CAUTION =
warnings come on at a conservative 380*F CHT, REDLINE at 400*F, and only =
twice has CHT on two cylinders reached 412*F.  Oil consumption has been =
low.  Engine oil analysis every 50 hours has not been revealing.  I fly =
LOP and do the "Big Mixture Pull" shortly after take off, with 19 gph, =
34"/2500 being a typical climb climb setting, occasionally keeping this =
in cruise vs 31.5".

Just sharing my recent experience with an expensive engine problem =
that's happened too early.

Jeff Liegner
Sparta, NJ


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