Turbo engine maintenance

I'm in the market to purchase a turbo aircraft...(specifically a 1979 Turbo
Lance)

Can someone tell me their experience with the engine maintenace in relation
to having to top overhaul the cylinders? I've heard from some owners that
you should only expect about 800 or so hours on the cyliners before having
to get them topped, while others have said if flown properly they should
make it to the engine TBO.

The plane I'm looking to buy has 800 hours SMOH and they haven't touched the
cylinders since the overhaul. Am I looking at a heavty bill to top the
cylinders soon? (I'm thinking about getting a prebuy done this week) Will a
compression check tell me what I need or does the A&P have to tear the
engine apart to really tell?

Thanks.

On Sun, 2 Oct 2005 23:21:21 -0400, "John Doe"
wrote:

I'm in the market to purchase a turbo aircraft...(specifically a 1979 Turbo
Lance)

Can someone tell me their experience with the engine maintenace in relation
to having to top overhaul the cylinders? I've heard from some owners that
you should only expect about 800 or so hours on the cyliners before having
to get them topped, while others have said if flown properly they should
make it to the engine TBO.

The plane I'm looking to buy has 800 hours SMOH and they haven't touched the
cylinders since the overhaul. Am I looking at a heavty bill to top the
cylinders soon? (I'm thinking about getting a prebuy done this week) Will a
compression check tell me what I need or does the A&P have to tear the
engine apart to really tell?

My father in law had a Seneca II (Continental TSIO-360s) that ate a
cylinder or two each annual. He was gentle with the throttles, and
used speedbrakes on approaches to slowdown (vs cutting the engines),
so I am not sure the cause, but he definitely went through a lot of
cylinders.

If I was buying a turbo'd (or for that matter high HP per cubic inch)
engine, I would plan on doing a top at least once on the way to TBO.

Contrast that with the Lyc O-360 in my PA28-180. 1400+ since SMOH,
same cylinders, and compressions are still in the mid/upper 70s.

-Nathan

"Nathan Young" wrote:

Continental
... ate a cylinder or two each annual.

Lyc[oming]
...1400+ since SMOH, same cylinders, and compressions are still in the
mid/upper 70s.

Hmmm...sounds familiar.

--
Dan
C172RG at BFM

It is going to depend a lot on how you fly the airplane and probably on luck
as well. I recently read in Light Plane Maitenance that the alloy used in
cylinders loses about 50% of its strength by 400F, so presumably the
cylinders will last longer if you fly at lower altitudes (where they will
run cooler) and at lower power settings. Of course, what is the point in
having a turbocharged engine if you are going to do that? When I had a Turbo
Lance, I cruised at 75% power and usually cruised in the mid-teens (the
terrain came up to the low teens). I never had an engine or cylinder
problem but I only had the airplane about 360hrs.

Mike
MU-2

"John Doe" wrote in message
news:_s10f.57789$8q.31419@lakeread01...
I'm in the market to purchase a turbo aircraft...(specifically a 1979
Turbo Lance)

Can someone tell me their experience with the engine maintenace in
relation to having to top overhaul the cylinders? I've heard from some
owners that you should only expect about 800 or so hours on the cyliners
before having to get them topped, while others have said if flown properly
they should make it to the engine TBO.

The plane I'm looking to buy has 800 hours SMOH and they haven't touched
the cylinders since the overhaul. Am I looking at a heavty bill to top
the cylinders soon? (I'm thinking about getting a prebuy done this week)
Will a compression check tell me what I need or does the A&P have to tear
the engine apart to really tell?

Thanks.

On Sun, 2 Oct 2005 23:21:21 -0400, "John Doe"
wrote:

below

Can someone tell me their experience with the engine maintenace in relation
to having to top overhaul the cylinders? I've heard from some owners that
you should only expect about 800 or so hours on the cyliners before having
to get them topped, while others have said if flown properly they should
make it to the engine TBO.

Are the cylinders 800 hours since new nitrides? oversized steels?
chrome? Factory o-haul? name-brand "new limits" o-haul? field o-haul?

Is it intercooled? What power setting used for cruise? Average cruise
altitude? Oil temp at cruise? CHT at cruise? TIT/fuel flow at cruise?
Oil consumption per hour? Calender time since OH? How long did it
typically "sit" without flying? Pretty sure I've mentioned this
before-how many total hours on the exhaust components SINCE NEW?

If the engine in question is not intercooled, has been operated at 75%
@peak TIT (or 50 degrees ROP) regardless of oil temp/CHT, flown
infrequently, it's entirely possible that the e-valve guides are
going/gone and the cam is well on it's way.

If the engine in question is intercooled, has spent most of it's life
with the oil temp at or below 200 degrees F, CHT at or below 400
degrees F, it's still entirely possible that the e-valve guides are
going.

The plane I'm looking to buy has 800 hours SMOH and they haven't touched the
cylinders since the overhaul. Am I looking at a heavty bill to top the
cylinders soon? (I'm thinking about getting a prebuy done this week) Will a
compression check tell me what I need or does the A&P have to tear the
engine apart to really tell?

If the engine isn't making metal, and periodic oil analysis looks
good, and the compression is good (no e-valve leaks) there is no
reason "to tear the engine apart". Don't know too many people selling
'planes that are going to let you "tear the engine apart" as part of a
pre-buy.

E-valve leaks on a Lycoming typically means the guides/valves are
trashed. At 800-1000 hours most big-six Lycoming E-valve guides are
marginal. Have personally had them go to TBO without this being an
issue (e-valves don't leak). Have also had them develop e-valve
leakage, requiring repair.

Again, not sure exactly what you are looking for. I've allegedly
maintained a crapload of turbocharged Lycomings for tens of thousands
of hours of operation, but my crystal ball's busted. Have seen S1AD's
go 1400-1600 hours without "cylinder" issues, have seen them with 400
hours that needed the cylinders thrown in a dumpster. It depends on
both the actual overhaul and the shivering mass of tissue between the
seat back and the yoke...

TC

wrote in message
...
On Sun, 2 Oct 2005 23:21:21 -0400, "John Doe"
wrote:

below

Can someone tell me their experience with the engine maintenace in
relation
to having to top overhaul the cylinders? I've heard from some owners that
you should only expect about 800 or so hours on the cyliners before having
to get them topped, while others have said if flown properly they should
make it to the engine TBO.

Are the cylinders 800 hours since new nitrides? oversized steels?
chrome? Factory o-haul? name-brand "new limits" o-haul? field o-haul?

Is it intercooled? What power setting used for cruise? Average cruise
altitude? Oil temp at cruise? CHT at cruise? TIT/fuel flow at cruise?
Oil consumption per hour? Calender time since OH? How long did it
typically "sit" without flying? Pretty sure I've mentioned this
before-how many total hours on the exhaust components SINCE NEW?

If the engine in question is not intercooled, has been operated at 75%
@peak TIT (or 50 degrees ROP) regardless of oil temp/CHT, flown
infrequently, it's entirely possible that the e-valve guides are
going/gone and the cam is well on it's way.

If the engine in question is intercooled, has spent most of it's life
with the oil temp at or below 200 degrees F, CHT at or below 400
degrees F, it's still entirely possible that the e-valve guides are
going.

The plane I'm looking to buy has 800 hours SMOH and they haven't touched
the
cylinders since the overhaul. Am I looking at a heavty bill to top the
cylinders soon? (I'm thinking about getting a prebuy done this week) Will
a
compression check tell me what I need or does the A&P have to tear the
engine apart to really tell?

If the engine isn't making metal, and periodic oil analysis looks
good, and the compression is good (no e-valve leaks) there is no
reason "to tear the engine apart". Don't know too many people selling
'planes that are going to let you "tear the engine apart" as part of a
pre-buy.

E-valve leaks on a Lycoming typically means the guides/valves are
trashed. At 800-1000 hours most big-six Lycoming E-valve guides are
marginal. Have personally had them go to TBO without this being an
issue (e-valves don't leak). Have also had them develop e-valve
leakage, requiring repair.

Again, not sure exactly what you are looking for. I've allegedly
maintained a crapload of turbocharged Lycomings for tens of thousands
of hours of operation, but my crystal ball's busted. Have seen S1AD's
go 1400-1600 hours without "cylinder" issues, have seen them with 400
hours that needed the cylinders thrown in a dumpster. It depends on
both the actual overhaul and the shivering mass of tissue between the
seat back and the yoke...

TC

Thanks TC,

Besides an oil analysis and compression check, what else should I be asking
the A&P to look for during a pre-buy to make sure I'm not buying a trashed
engine?

I seriously doubt the seller is going to tell me he's trashed the engine
running at peak temps.

On Mon, 3 Oct 2005 21:00:20 -0400, "John Doe"
wrote:

snip
Again, not sure exactly what you are looking for. I've allegedly
maintained a crapload of turbocharged Lycomings for tens of thousands
of hours of operation, but my crystal ball's busted. Have seen S1AD's
go 1400-1600 hours without "cylinder" issues, have seen them with 400
hours that needed the cylinders thrown in a dumpster. It depends on
both the actual overhaul and the shivering mass of tissue between the
seat back and the yoke...

TC

Thanks TC,

Besides an oil analysis and compression check, what else should I be asking
the A&P to look for during a pre-buy to make sure I'm not buying a trashed
engine?

Cut the oil filter, inspect the suction screen. Look at previous
oil/filter change intervals. If it's had another recent pre-buy doing
all this, you aren't going to see much. If the filter's been changed
"early" (like immediately after you got off the phone setting up the
pre-buy) it's entirely possible somebody's trying to hide something.

All the questions I listed earlier are pertinent. You DO NOT want a
no-name field overhaul with minimal documentation, you DO NOT want
chrome cylinders, you DO NOT want high-time exhaust components, you DO
NOT want an engine that has been sitting for extended periods of time
without being preserved.

I seriously doubt the seller is going to tell me he's trashed the engine
running at peak temps.

Play dumb and interested. At a minimum, ask about %power at
cruise/fuel flow/ITT-after all, you want to keep operating it the same
way it's been operated ; ) Ask him/her to take you for an extended
test hop to "see how it flies". Pay close attention to his/her
climb/cruise profile & power settings and the indicated temps. Ask
about performance and altitude & have him/her show you. Check the oil
consumption after 30 minutes in cruise, minimum. Paying for a little
fuel can net you a lot of information.

TC

If it has a recording engine analyzer installed (many a/c of that class,
performance do), ask for a memory dump of whatever is stored in its memory
and watch that memory dump take place, if possible. That could tell a lot
about how it's been operated.

DL

wrote in message
...
snip.

Play dumb and interested. At a minimum, ask about %power at
cruise/fuel flow/ITT-after all, you want to keep operating it the same
way it's been operated ; ) Ask him/her to take you for an extended
test hop to "see how it flies". Pay close attention to his/her
climb/cruise profile & power settings and the indicated temps. Ask
about performance and altitude & have him/her show you. Check the oil
consumption after 30 minutes in cruise, minimum. Paying for a little
fuel can net you a lot of information.

TC

"DL" wrote in message
news
If it has a recording engine analyzer installed (many a/c of that class,
performance do), ask for a memory dump of whatever is stored in its memory
and watch that memory dump take place, if possible. That could tell a lot
about how it's been operated.


I know the JDIs have that capability, does the EI analyzers have that option
as well? (I think that's what this one has)

I seriously doubt the seller is going to tell me he's trashed the engine
running at peak temps.

He may show you on a demo flight so you can see how fast it goes.

Mike
MU-2