Turbo engine maintenance

One thing to do is check the turbocharger. Climb to altitude (up
around 18K or so) and pull the RPM back. See how much MP you can get.
[Merlyn used to have a nice chart - might be on their web site.] A
worn turbocharger won't give rated boost up in the thin air (but almost
any piece of scrap metal will give lots of boost down low).

Check the turbocharger housing very carefully for cracks. Case cracks
are not uncommon. Induction leaks are also a pain (usually trivial to
fix, but can be hard (timeconsuming) to find).

OTOH, there is no reason why a well maintained system shouldn't make it
to TBO or close to it (new TCM cylinders being the exception - they
tend to last 400-700 hours, period!). I fly a turbo Arrow and really
enjoy the "high flight." I won't say I wouldn't buy a non-turbo
aircraft, but it would be hard to give up the turbo after having one.

"jmk" wrote in message
ups.com...
One thing to do is check the turbocharger. Climb to altitude (up
around 18K or so) and pull the RPM back. See how much MP you can get.
[Merlyn used to have a nice chart - might be on their web site.] A
worn turbocharger won't give rated boost up in the thin air (but almost
any piece of scrap metal will give lots of boost down low).

Check the turbocharger housing very carefully for cracks. Case cracks
are not uncommon. Induction leaks are also a pain (usually trivial to
fix, but can be hard (timeconsuming) to find).

OTOH, there is no reason why a well maintained system shouldn't make it
to TBO or close to it (new TCM cylinders being the exception - they
tend to last 400-700 hours, period!). I fly a turbo Arrow and really
enjoy the "high flight." I won't say I wouldn't buy a non-turbo
aircraft, but it would be hard to give up the turbo after having one.


Is there an altitude, where you have to start using more and more fuel to
keep the engine cool to a point where it's not worth the extra few knots you
might get by flying higher?

If you are talking about the Turbo Lance with an intercooler this isn't a
problem

Mike
MU-2

"John Doe" wrote in message
news:erE0f.500$L24.30@lakeread01...

"jmk" wrote in message
ups.com...
One thing to do is check the turbocharger. Climb to altitude (up
around 18K or so) and pull the RPM back. See how much MP you can get.
[Merlyn used to have a nice chart - might be on their web site.] A
worn turbocharger won't give rated boost up in the thin air (but almost
any piece of scrap metal will give lots of boost down low).

Check the turbocharger housing very carefully for cracks. Case cracks
are not uncommon. Induction leaks are also a pain (usually trivial to
fix, but can be hard (timeconsuming) to find).

OTOH, there is no reason why a well maintained system shouldn't make it
to TBO or close to it (new TCM cylinders being the exception - they
tend to last 400-700 hours, period!). I fly a turbo Arrow and really
enjoy the "high flight." I won't say I wouldn't buy a non-turbo
aircraft, but it would be hard to give up the turbo after having one.


Is there an altitude, where you have to start using more and more fuel to
keep the engine cool to a point where it's not worth the extra few knots
you
might get by flying higher?

"John Doe" wrote in message
news:erE0f.500$L24.30@lakeread01...

"jmk" wrote in message
OTOH, there is no reason why a well maintained system shouldn't make it
to TBO or close to it (new TCM cylinders being the exception - they
tend to last 400-700 hours, period!). I fly a turbo Arrow and really
enjoy the "high flight." I won't say I wouldn't buy a non-turbo
aircraft, but it would be hard to give up the turbo after having one.


Is there an altitude, where you have to start using more and more fuel to
keep the engine cool to a point where it's not worth the extra few knots
you
might get by flying higher?

If you want cooler, use lean-of-peak; lose a few knots, but gain
significantly less fuel and lower TIT/CHT temps.


--
Matt

---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO

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

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.

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

TC,

Thanks for taking the time to comment on my posts. The plane just went into
the shop today for a prebuy and I'll have some words within a day or two on
the status of the engine.

It appears you're not a big fan of the Turbo Lance. What do you recommend
as a better combo? I've look at an A36 but they're quite a bit more cash
for not alot of gain. I think my other option is to give up on the turbo
and just look for a straight tail lance that's in good shape.

"John Doe" wrote in message
news:MUD2f.1804$L24.723@lakeread01...
Thanks for taking the time to comment on my posts. The plane just went
into the shop today for a prebuy and I'll have some words within a day or
two on the status of the engine.

It appears you're not a big fan of the Turbo Lance. What do you recommend
as a better combo? I've look at an A36 but they're quite a bit more cash
for not alot of gain. I think my other option is to give up on the turbo
and just look for a straight tail lance that's in good shape.

John, the used airplane market is pretty efficient and, yes, an A36 is
better in every way than a PA32. When I purchased a Turbo Lance as my first
plane I did it because. it offered a good combination of positive atributes
relative to the price. It is the same at all levels, Piper is low quality
compared to Beech and Citations don't compare to Falcons.

Mike
MU-2

On Mon, 10 Oct 2005 20:43:21 -0400, "John Doe"
wrote:

TC,

Thanks for taking the time to comment on my posts. The plane just went into
the shop today for a prebuy and I'll have some words within a day or two on
the status of the engine.

It appears you're not a big fan of the Turbo Lance. What do you recommend
as a better combo? I've look at an A36 but they're quite a bit more cash
for not alot of gain. I think my other option is to give up on the turbo
and just look for a straight tail lance that's in good shape.

Have allegedly been around the block with the Turbo Lance, the Turbo
Saratoga (fixed-gear and retract-SP) but not the 'toga II TC. Have
been under the hood of a couple of 'toga II's, took one for a ride and
liked what I saw, but they were coming out as I was getting out of the
business-have no real experience with them.

When I got out a few years ago, the Turbo T-Lance was cheaper than
anything else in it's class. Personally, I was never too fond of the
way that they behaved in the air (compared to the T-tail or straight
tail NA Lance, or the Cherokee 6), and don't care for the engine
installation at all.

Unfortunately, and please don't take this personally, it means that
they tended to attract a certain type of owners, and often were not
well-maintained or operated properly. As Mr. R has indicated, it also
meant, however, a few years ago, you could buy a lot of airplane for
less.

The engine/install has recurring AD issues on the exhaust, a funky
up-draft cooling system, and runs HOT. The Turbo 'toga SP installation
is almost identical, and also runs hot, but not quite as hot for some
reason (cruise speed?).

If you look at the Deakin dude's thoughts on max CHT/oil temp with
regard to engine longevity, a stock T T-Lance operated at 75% power at
cruise is going to exceed these numbers during operation at even
slightly elevated OAT's. Basically, a lot of the time it is going to
be a 65% power cruise aircraft.

Even operating at 65% it can be pushing acceptable CHT/oil temp
limits. Put Turbo 'toga upper cowl "gills" on a couple, didn't seem to
help much-but it did help keep the paint on the top cowl from
blistering after shut-down. As I indicated to you in earlier posts,
for whatever reason, the intercooler kit removes most of these
limitations. I'm sorry I don't have more info, but the last I had
heard, the intercooler company's assets had been sold, which is a darn
shame.

Had one intercooled Turbo 'Toga SP that I took care of (before, during
and after the intercooler install), and really, really enjoyed flying
it. I assume the flight characteristics changed from both the tapered
wing and the straight tail. A 300 hp Cherokee Six, or Lance can also
be a nice choice. If you are a flat-lander and not hell-bent for
speed, their performance is better than what you would expect. It is a
lot harder to abuse the normally-aspirated engine, and the
installation condition (baffling, etc) is not as super-critical.

The A36, unfortunately is in a different class. The cruise performance
is excellent, and there really is no comparison between the
construction of the aircraft and it's mechanical systems. Again, as
Mr. R indicated, you don't get something for nothing. They are more
expensive to purchase, but realistically are not really that much more
expensive to maintain (if you compare to the Lance or the retract-SP).

I allegedly had the opportunity to take care of a couple of the
factory IO-550 versions, and converted one to the IO-550
configuration. Never had the opportunity to fly it, but had one show
up on the ramp with an STC-installed 350 HP TIO-540. If that
installation works as well as the Chieftain does, it would be just
about the ultimate A-36. In theory would make real close to the same
power @ 65% as the IO-550 @ 78% (max continuous HP).

Unless things have changed a whole lot in the few years, a clean A36
is as close to a sure thing to buy, fly, and if you don't bend it,
sell at a profit as you get in GA.

Hope some of this helps;

TC