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Date: Tue, 20 Mar 2012 08:18:07 -0400
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From: vtailjeff@aol.com
Subject: Re: [LML] Top End Overhaul (TSIO550E) at 440 hrs TT (LIVP)
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Jeff,

How many hours on engine since new?

Jeff

Sent from my iPad

On Mar 19, 2012, at 6:17 AM, "Jeffrey Liegner, MD" <liegner@embarqmail.com> w=
rote:

> Lancair Friends,
>=20
> During my annual inspection, I found six cylinders with low compressions (=
20-30 over 80).  Yes, Master Orifice and all the right techniques.  We shoul=
d know by now that BORESCOPE is the important step, and this was done.  Exha=
ust valve seats were eroded and pitted, causing leakage.  Valve face had mil=
d thermal changes and stems were good.  A repair was planned.
>=20
> Cylinders were pulled and inspected, confirming exhaust valve seats were t=
he problem, and replacements were planned.  Further inspection showed some m=
ild 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 woul=
d get the ECI Nickel+Carbide coating (CermiNil process).  The turn around ti=
me would have been four weeks minimum plus further reassembly and shipping, o=
r I could get ready to go refurb'd compete cylinders, already coated and rea=
ssembled, immediately.  Hence, a complete Top End Overhaul.
>=20
> Discussions regarding why this 2006 fast build TCM engine (flying since 20=
07, now out of warranty) was having this problem revealed several illuminati=
ng tidbits.  One custom engine shop said "those cylinders are doomed from th=
e first time you run the engine."  Others explained that these engines are a=
ssembled with factory-style production, not custom production, and so parts a=
re placed and efficiencies taken to improve production.  Another explained t=
hat the valve seats are pre-reamed rather than post-reamed after installatio=
n, creating an opportunity for poor interaction with the valve edge, malposi=
tion and wobble, leading to early failure.  This appears to be a common issu=
e for the engines around my 2006 era.  It's not confirmed, but there is rumo=
r that their practice of using pre-reamed guides ended after they finished u=
sing up their inventory in late 2007.
>=20
> 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 t=
o 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 welcom=
ed).  I will see about moving hangers or more effectively sealing the perime=
ter of my hanger floor.  Other ideas are welcomed.
>=20
> I have Chelton and full engine monitoring.  The engine's CAUTION warnings c=
ome 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 a=
nalysis every 50 hours has not been revealing.  I fly LOP and do the "Big Mi=
xture Pull" shortly after take off, with 19 gph, 34"/2500 being a typical cl=
imb climb setting, occasionally keeping this in cruise vs 31.5".
>=20
> Just sharing my recent experience with an expensive engine problem that's h=
appened too early.
>=20
> Jeff Liegner
> Sparta, NJ
>=20
>=20
>=20
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>=20
> <P18BE65C5_3>