1976 Overhaul, 1100 Hours..Pass???/

You would need to get a filter sample too. An oil analysis will only catch
wear particles small enough to pass the filter.

Mike
MU-2


"pbc76049" wrote in message
...
Start it, get it warm and pull an oil sample. If the cam it tits up,
the metal will be visable in the sample. Also, pulling a single jug
won't get ALL the lobes visable, and I've never seen ALL the lobes have
trouble
at the same time.

You should also note that this particular plane has damage history X 2. Check the NTSB site.

The people who think you can detect camshaft lobe damage by oil analysis might want to check this - http://www.sacskyranch.com/camshaft.htm They also describe the easiest method for camshaft lobe inspection for this aircraft. They also give the proper method for filter examination.

Jack,

I got the AMU term from the Mooney email list I subscribe to at
aviating.com. I liked it so I use it freely....

Jon Kraus
'79 Mooney 201
4443H @ TYQ

Jack Allison wrote:
Jon Kraus wrote:

Aviation Monetary Unit. 1 AMU = $1000. So our spouses won't know
how much we are spending on our planes. :-)


Oops, replied to the earlier post before I scrolled down and saw your
reply Jon. IIRC, I first heard the term from you when you were in the
buying phase of your Mooney. Where did you hear it from?

Lycoming says 12 years or 2000 hours, whichever comes first. However,
many airplanes exceed these "limits" under certain conditions. Flight
schools regularly exceed 2000 hours because their engines are flown so
frequently they avoid internal corrosion which is the main killer of air
cooled engines in airplanes. So, if flying MORE frequently makes the
engine last longer, guess what flying LESS frequently does???

Exactly.

One poster responded that the engine was probably rusted up internally.
Others said that this conclusion was "defective" (I am using polite
language). Their opinions, your money. Others also balked about pulling
a jug for a prebuy. Normally, it is true that this is not done. There
are plenty of uninformed buyers with enough credit to buy a bird
uninspected and sight unseen. So, an unusual request like pulling a jug
will no doubt get you a firm "No F^@%!*G Way" of some kind of robust
belly laugh.

It is still your money. If you want to price the thing as a runout and
deduct the full overhaul value (along with any other firewall forward
item likely to be worn out - like everything) from the price and make an
offer, go right ahead. I would. However, it is likely the owner will
pass on such an offer and sell the plane to a less informed buyer,
probably for full price.

The reason many owners will tell you the engine is perfectly fine is
because they have an old overhaul themselves and are in denial. Some
have glowing anecdotes about old overhauls that are "running fine". I
have never seen anyone follow up with the report that the "fine" engine
self destructed some time after they weighed in with their opinion. If
you are curious, call up the engine shops and ask what they are seeing
for this particular engine/bird combination. Might be a good piece of info.

Compressions are ONE of the signs. Calendar time since overhaul, hours
since overhaul, oil analysis, oil CONSUMPTION, climate, frequency of
hours flown, type of use (training, long x-country, pipeline survey,
etc) are all contributing factors.

Good luck,
Mike

wrote:
Hey Guys,

I'm looking at at 172 that has 1100 hours since overhaul, holding 73/90
++ on all cylinders...the only thing holding me back, last overhaul was
1976...

I've talked to several seasoned pilots / aircraft owners that say as
long as it's holding good compressions, don't sweat it....

Any opinions?

Thanks,

Jamie A. Landers
PP-ASEL
Looking for a 172

Well, ok - but if you [devil's advocate here :-) ] insist the airplane
should command a premium due to its supposedly mid-time, *thirty-year
old* overhaul, then you might just have to let someone peek little more
than usual. Taking off a cylinder on a horizontally opposed, air-cooled
engine like an O-320 is not such a big deal, after all. And the cam is
very vulnerable on disused Lycomings, no question about that.

I would verify the accuracy of the log books by checking for entries related
to the 1971 and 1975 substantial damage accident reports as mentioned by
another poster.
I would be very wary of the logs if they are not recorded.

"JJS" jschneider@remove socks cebridge.net wrote in message
...
I'm looking at at 172 that has 1100 hours since overhaul, holding 73/90
++ on all cylinders...the only thing holding me back, last overhaul was
1976...

Don't pass yet!
Are you sure that's not supposed to read 73 / 80 compressions on all
cylinders?
How many hours has it flown in the last year?
In the last 6 months?
Does it have chrome cylinders?
Does the static run-up meet the type certificate minimum rpm?
How many major overhauls and was the last one a quality job?
Is the engine on a low to mid time airframe?
Is the price discounted enough to account for the fact you may need an
overhaul soon?

I'm gonna get flamed here, but if it has been flying quite a bit recently,
makes good static rpm, has chrome
cylinders and good logbooks, you may be on to a good buy. I'd have a
pre-buy inspection done including a borescope
of the cylinders. You should also consider asking the trusted A&P to pull
a jug and inspect the camshaft. If
everything checks out okay make an offer based on the above
considerations.
--
Joe Schneider
8437R
(Remove No Spam to Reply)




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OK, let's say that you pull a jug for "inspection". Exactly what do you
expect to find by this? Where is this "rust" going to be? At BEST you will
see four camshaft lobes. That isn't going to tell you squat except for
those four lobes. If the engine has been run recently, all the splash hot
oil will have removed any rust particles you have a chance of seeing.

Now you've pulled the jug. New rings, a hone job on the cylinder, new
cylinder gasket kit, change oil to breakin oil, and for what? And who is
going to pay for it? Lemme TELL you who is going to pay for it, buy the
airplane or not. And if the airplane doesn't break in properly within a
couple of dozen hours, guess who gets to pay for the REdo. You do, redo and
all.

Airplanes are best sold on the "this is the price, no matter what your
mechanic finds" basis. You find some stuff that doesn't make you want to
buy, that's fine. No problem. See ya later.

Jim



"Mike Spera" wrote in message
link.net...


.. Others also balked about pulling
a jug for a prebuy. Normally, it is true that this is not done. There are
plenty of uninformed buyers with enough credit to buy a bird uninspected
and sight unseen. So, an unusual request like pulling a jug will no doubt
get you a firm "No F^@%!*G Way" of some kind of robust belly laugh.

Hands down, price it as a runout.

Even if there is zero corrosion, engines have a lot of soft parts,
rubber and cork gaskets and the like that go bad with age alone.
Corrosion is the insidious enemy of engines that sit. It would be better
if the engine were 6 years old and 2000 hours then 30 years and 1100
hours. Unless it was stored in corrosion inhibiting oil for most of
those years, that engine has corrosion.

Lycoming says TBO is 2000hrs or 12yrs, whichever comes first.

Any time you get out of that engine is a bonus.



In article .com,
wrote:

Hey Guys,

I'm looking at at 172 that has 1100 hours since overhaul, holding 73/90
++ on all cylinders...the only thing holding me back, last overhaul was
1976...

I've talked to several seasoned pilots / aircraft owners that say as
long as it's holding good compressions, don't sweat it....

Any opinions?

Thanks,

Jamie A. Landers
PP-ASEL
Looking for a 172

Exactly why I offered the advice that I did. Namely, pulling a cylinder
is not what most think of as a "normal" prebuy operation. Also, the
suggestion may get a "smart" reply or outright laugh.

I agree that pulling one jug gives you a limited view. What are you
looking for? Well, how about a lobe that is ground off 30-50%? for
starters. If you catch a copy of Light Plane Maintenance, they have an
easier way to determine this on all the lobes by dial gauging the backs
of the tappets. Still requires some disassembly, but nowhere near as
radical as pulling a jug. Please don't mix up the pushrods.

Since Lycomings may run fine with a lobe seriously ground off, this may
be a better alternative.

Above all, as I said, chances are that any "unusual" requests (like
these) beyond the normal "once over lightly pre-buy" will likely be
rejected.

Sarcasm and anger noted below, although I'm not sure what I said to
provoke it.

Good Luck,
Mike


OK, let's say that you pull a jug for "inspection". Exactly what do you
expect to find by this? Where is this "rust" going to be? At BEST you will
see four camshaft lobes. That isn't going to tell you squat except for
those four lobes. If the engine has been run recently, all the splash hot
oil will have removed any rust particles you have a chance of seeing.

Now you've pulled the jug. New rings, a hone job on the cylinder, new
cylinder gasket kit, change oil to breakin oil, and for what? And who is
going to pay for it? Lemme TELL you who is going to pay for it, buy the
airplane or not. And if the airplane doesn't break in properly within a
couple of dozen hours, guess who gets to pay for the REdo. You do, redo and
all.

Airplanes are best sold on the "this is the price, no matter what your
mechanic finds" basis. You find some stuff that doesn't make you want to
buy, that's fine. No problem. See ya later.

J



"Mike Spera" wrote in message
link.net...


. Others also balked about pulling

a jug for a prebuy. Normally, it is true that this is not done. There are
plenty of uninformed buyers with enough credit to buy a bird uninspected
and sight unseen. So, an unusual request like pulling a jug will no doubt
get you a firm "No F^@%!*G Way" of some kind of robust belly laugh.

"Even if there is zero corrosion, engines have a lot of soft parts,
rubber and cork gaskets and the like that go bad with age alone."

Then why doesn't mine leak? or use oil? or show some iron in the oil
analysis (we'll have an update on that in a couple of months though).

I agree there are a lot of raunchy abused and marginally overhauled
engines out there, but with proper care some engines can last well
beyond TBO.

Even aircraft engines don't use cork anymore.