Oil leak on top of the engine

[Jay Honeck]

It seems to be the season for finding oil leaks.

At our completely uneventful annual (just finished two days ago) I asked my
shop to investigate a new leak that I had detected when I de-cowled the
engine for the inspection. All across the top of our 3-year-old, 500-hour
engine, down the seam where the case halves join together, right where the
push rods attach to the case, was a puddle of fresh, clean oil -- enough to
look like I had just spilled some while adding oil...

Trouble was, I HADN'T added any oil recently. With our new air/oil
separator, I no longer need to add oil between oil changes, so it had been
some 24 flight hours since I had last added oil.

With no obvious source of the leak, my mechanic thoroughly cleaned the
engine and resolved to fly it to see where the oil was coming from. The
flying weather wouldn't cooperate until today, but this morning we flew the
plane on its post-annual test flight, found a squawk or two, and returned to
the shop to fix these and check for the source of the leak.

The total flight time was only 0.7 hours, yet the top of the engine once
again looked like I had spilled oil while filling. It was right along the
case halves seam, so with no other apparent source my mechanic figured the
first place to start was to check the torque on the case bolts.

He reached for the first one, and we were both astounded when he was able to
tighten it -- by hand! One by one, all of the case nuts were found to be
very loose (although that was the only one that was hand-tight), and needed
to be re-torqued to 190 inch pounds of torque.

After tightening those, he checked the prop governor housing, and found
those bolts to be way loose, too. Essentially the whole top of the engine
was loose, and oil was leaking at the seam.

After re-torquing everything to spec, I test flew the plane for another 0.5
hours, and was happy to see everything bone dry once again.

Questions:

1. Is this something one should expect after 500 hours of shaking and
rattling? Do these bolts just plain loosen over time, going from hot to
cold hundreds of times?

2. Do you guys re-torque these bolts on a schedule?

3. Is this something your A&P checks at every annual? My guys were clearly
surprised to find these bolts so loose -- and they are the guys who rebuilt
the engine.

4. Are there any other bolts -- say, on the BOTTOM of the engine -- that I
should check for looseness? I looked but couldn't see any.

5. Should I apply LocTite to these bolts?

I suspect I'll be checking those bolts regularly from now on!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Fly]

No they shouldn't be that loose. Torqueing a bolt is to put a higher load
on it then the load it sees in service.
It wasn't torqued to begin with or something else has changed..

I would check all the cylinder holdown nuts and thru-bolts before I flew it
again.

Lyc or TCm has a service bltn explaining how to measure the rotating
resistance of the engine by using a spring scale on the prop. Take a
measurement then torque the thru bolts then take another measurement.
A significant change is signs of bearing pinch.

Good luck and hope for the best.

Kent Felkins

[Dude]

"Fly" > wrote in message
...
> No they shouldn't be that loose. Torqueing a bolt is to put a higher
> load
> on it then the load it sees in service.
> It wasn't torqued to begin with or something else has changed..
>
> I would check all the cylinder holdown nuts and thru-bolts before I flew
> it
> again.
>
> Lyc or TCm has a service bltn explaining how to measure the rotating
> resistance of the engine by using a spring scale on the prop. Take a
> measurement then torque the thru bolts then take another measurement.
> A significant change is signs of bearing pinch.
>
> Good luck and hope for the best.
>
> Kent Felkins
>
>

This one gets my vote for thread of the week, I will watch out for this from
now on. I am suprised its not on the annual check list. In fact, I may have
to go check for that.

[Jay Honeck]

> A significant change is signs of bearing pinch.

What's "bearing pinch"?

Dunno if this matters, but all compressions are in the high 70s, oil
consumption is better than average, and it runs great.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Jon A.]

DAMN!

No, that's absolutely not normal. Poor workmanship at the rebuilder.

There are bolts that should have been retorqued at a certain hour.
The shop would have specified which ones.

I really don't know of anyone who makes it a habit to check the torque
on all the engine bolts at each annual. Things like exhaust studs
hardware and intake bolts are checked.

Understand this. If the case is fretting, as it does when bolts are
loose, it's a very serious situation. If this were my engine, I would
have another mechanic check the torque of the through bolts. If
they're off you need to clean it up very well and run it for about
another 1/2 hour on the ground. Do Not Fly This Airplane. If wet,
the engine needs to be pulled and the disassembled, cases sent out and
reassembled. It'll give you something to talk about, anyway.

Don't take my word for it, contact a real engine house for advice and
let the world know if I'm wrong.

I seem to remember being strongly criticized after saying something
about soliciting recommendations for a shop via the newsgroups when
you did it a few years back.


On Thu, 10 Feb 2005 21:25:10 GMT, "Jay Honeck"
> wrote:

>It seems to be the season for finding oil leaks.
>
>At our completely uneventful annual (just finished two days ago) I asked my
>shop to investigate a new leak that I had detected when I de-cowled the
>engine for the inspection. All across the top of our 3-year-old, 500-hour
>engine, down the seam where the case halves join together, right where the
>push rods attach to the case, was a puddle of fresh, clean oil -- enough to
>look like I had just spilled some while adding oil...
>
>Trouble was, I HADN'T added any oil recently. With our new air/oil
>separator, I no longer need to add oil between oil changes, so it had been
>some 24 flight hours since I had last added oil.
>
>With no obvious source of the leak, my mechanic thoroughly cleaned the
>engine and resolved to fly it to see where the oil was coming from. The
>flying weather wouldn't cooperate until today, but this morning we flew the
>plane on its post-annual test flight, found a squawk or two, and returned to
>the shop to fix these and check for the source of the leak.
>
>The total flight time was only 0.7 hours, yet the top of the engine once
>again looked like I had spilled oil while filling. It was right along the
>case halves seam, so with no other apparent source my mechanic figured the
>first place to start was to check the torque on the case bolts.
>
>He reached for the first one, and we were both astounded when he was able to
>tighten it -- by hand! One by one, all of the case nuts were found to be
>very loose (although that was the only one that was hand-tight), and needed
>to be re-torqued to 190 inch pounds of torque.
>
>After tightening those, he checked the prop governor housing, and found
>those bolts to be way loose, too. Essentially the whole top of the engine
>was loose, and oil was leaking at the seam.
>
>After re-torquing everything to spec, I test flew the plane for another 0.5
>hours, and was happy to see everything bone dry once again.
>
>Questions:
>
>1. Is this something one should expect after 500 hours of shaking and
>rattling? Do these bolts just plain loosen over time, going from hot to
>cold hundreds of times?
>
>2. Do you guys re-torque these bolts on a schedule?
>
>3. Is this something your A&P checks at every annual? My guys were clearly
>surprised to find these bolts so loose -- and they are the guys who rebuilt
>the engine.
>
>4. Are there any other bolts -- say, on the BOTTOM of the engine -- that I
>should check for looseness? I looked but couldn't see any.
>
>5. Should I apply LocTite to these bolts?
>
>I suspect I'll be checking those bolts regularly from now on!

[Mark Hansen]

On 2/10/2005 15:12, Jay Honeck wrote:

>> A significant change is signs of bearing pinch.
>
> What's "bearing pinch"?
>
> Dunno if this matters, but all compressions are in the high 70s, oil
> consumption is better than average, and it runs great.

From my automotive days, this is where the bearings are either
not seated properly, or are not the proper size to fit, and
torquing down the case bolts results in compressing the bearings
onto the crank, resulting in restricted movement and generally
a chewing up of the bearings and/or crank.


--
Mark Hansen, PP-ASEL
Sacramento, CA

[Peter R.]

"Jon A." > wrote:

> I really don't know of anyone who makes it a habit to check the torque
> on all the engine bolts at each annual. Things like exhaust studs
> hardware and intake bolts are checked.

The case bolts on my previous Continental IO-520, circa 1987, had white
paint stripes painted on them to indicate whether they had come loose. The
previous owner, a one-time automotive racer, had a colorful name for these
stripes but at the moment I cannot recall it.

--
Peter













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[Jon A.]

On Thu, 10 Feb 2005 18:51:03 -0500, "Peter R."
> wrote:

>"Jon A." > wrote:
>
>> I really don't know of anyone who makes it a habit to check the torque
>> on all the engine bolts at each annual. Things like exhaust studs
>> hardware and intake bolts are checked.
>
>The case bolts on my previous Continental IO-520, circa 1987, had white
>paint stripes painted on them to indicate whether they had come loose. The
>previous owner, a one-time automotive racer, had a colorful name for these
>stripes but at the moment I cannot recall it.

You can use a product called "Torque Seal", available from Spruce for
this. All of your fuel connections should be done. Doesn't actually
seal the torque, but shows you if something has moved.

[Peter R.]

"Jon A." > wrote:

> You can use a product called "Torque Seal", available from Spruce for
> this. All of your fuel connections should be done. Doesn't actually
> seal the torque, but shows you if something has moved.

I think I now recall the name the previous owner called those paint
stripes. "Sabotage spotter."

--
Peter













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[Fly]

>
> What's "bearing pinch"?
>
>

Severe case of the crankcase halves rubbing against each other and over time
grinding away.
Thus the bore for that crank bearing is smaller. It keeps working ok for
a while because its a loosed fit. But if you retorque the thru bolts you'll
squeeze the bore back tighter and its smaller diameter will pinch the
bearing halves together, and maybe cause direct metal to metal contact
between the crank and bearing.

Many engines have dowel pins that fit the halves together to minimize
fretting.

Btw, I don't have the torque value bulletin handy but it seems tha the case
spine bolts are only torqued down to 7-10 ft lbs. Not that much but
definitely more than finger tight!

Kent Felkins

[Jay Honeck]

> There are bolts that should have been retorqued at a certain hour.
> The shop would have specified which ones.

No one I've talked to has heard of this schedule with regard to the case
bolts. Have you got a Lycoming reference for this?

> Understand this. If the case is fretting, as it does when bolts are
> loose, it's a very serious situation. If this were my engine, I would
> have another mechanic check the torque of the through bolts.

What are the "through bolts"? Are these the bolts I'm talking about, or
different ones?

> Do Not Fly This Airplane.

Too late. We torqued everything to spec, and flew it uneventfully for half
an hour, at all throttle settings, at altitudes up to 4000 feet. No leakage
noted, all six bars on the JPI engine analyzer looked fine, everything
sounded and ran perfectly.

> If wet,
> the engine needs to be pulled and the disassembled, cases sent out and
> reassembled.

What do you mean by "if wet"?

Thanks,
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[[email protected]]

On Thu, 10 Feb 2005 16:39:48 -0500, "Gene Kearns"
> wrote:

snip

>This should be expected and the bolts should be checked at annual. If
>not, fretting corrosion can take a *real* toll on the case.

I strongly disagree.

>Annual is often enough.... unless "on condition" becomes necessary.

I strongly disagree.

>They shouldn't have been *that* loose, but they should have already
>been checked. I wonder if they were *ever* torqued properly. The #1
>cause of leaking cases (that were correctly assembled) is letting the
>case bolts get loose.

Now this I'll agree with, maybe.

I cannot honestly remember EVER having to re-torque on the case bolts
on a Lycoming. Have come across a few leaky spine seams, NEVER had one
caused by any/all the bolts being "loose".

Then again, I've only allegedly personally witnessed around 70-80,000
hours (conservative estimate) of Brand L operation from the
perspective of an alleged maintenance technician, so WTF do I know.

The only periodic "re-torque" on recips that I have been exposed to is
on cylinder base studs on radial engines.

BTW, only ever had one "properly" overhauled Brand L engine not make
it to TBO that I've hung on an engine mount and then regularly
maintained. Maybe I wuz just real lucky.

TC

[Stealth Pilot]

On Fri, 11 Feb 2005 06:13:39 GMT, wrote:


>Now this I'll agree with, maybe.
>
>I cannot honestly remember EVER having to re-torque on the case bolts
>on a Lycoming. Have come across a few leaky spine seams, NEVER had one
>caused by any/all the bolts being "loose".
>
>Then again, I've only allegedly personally witnessed around 70-80,000
>hours (conservative estimate) of Brand L operation from the
>perspective of an alleged maintenance technician, so WTF do I know.
>
>The only periodic "re-torque" on recips that I have been exposed to is
>on cylinder base studs on radial engines.
>
>BTW, only ever had one "properly" overhauled Brand L engine not make
>it to TBO that I've hung on an engine mount and then regularly
>maintained. Maybe I wuz just real lucky.
>
>TC

I must admit that I have followed this with interest. the torquing
applied to case bolts should mean that they never come loose.

torsional vibration can hammer the merry hell out of an engine without
appearing to the pilot as a vibration. one wonders.....

VW aero engine conversions done here in perth (by a company that no
longer exists) once saw crank case failures. after some expensive
testing torsional vibration was identified as the cause. a heavy prop
was bringing one of the vibrational modes down into the operating
range.

intriguing
Stealth Pilot

[Jon A.]

On Fri, 11 Feb 2005 03:30:22 GMT, "Jay Honeck"
> wrote:

>> There are bolts that should have been retorqued at a certain hour.
>> The shop would have specified which ones.
>
>No one I've talked to has heard of this schedule with regard to the case
>bolts. Have you got a Lycoming reference for this?

No, your rebuilder should have it. May be 10 hours or so.
>
>> Understand this. If the case is fretting, as it does when bolts are
>> loose, it's a very serious situation. If this were my engine, I would
>> have another mechanic check the torque of the through bolts.
>
>What are the "through bolts"? Are these the bolts I'm talking about, or
>different ones?

I think you're speaking of the case bolts. The through bolts go all
the way through the case near the cylinder bases. If the case bolts
weren't done properly, there's no reason to believe the through bolts
were, either.
>
>> Do Not Fly This Airplane.
>Too late. We torqued everything to spec, and flew it uneventfully for half
>an hour, at all throttle settings, at altitudes up to 4000 feet. No leakage
>noted, all six bars on the JPI engine analyzer looked fine, everything
>sounded and ran perfectly.
>
You'll not see anything special on the engine analyzer. Ask if they
retorqued the cylinders and through bolts. Not a hard job, but very
time consuming removing all the junk around the engine.

>> If wet,
>> the engine needs to be pulled and the disassembled, cases sent out and
>> reassembled.
>
>What do you mean by "if wet"?

Signs of further leakage.
>
>Thanks,

Stay safe, I may need a room one day!

[Fly]

>> Too late. We torqued everything to spec, and flew it uneventfully for
half
> an hour, at all throttle settings, at altitudes up to 4000 feet. No
leakage
> noted, all six bars on the JPI engine analyzer looked fine, everything
> sounded and ran perfectly.


The point I'm trying to make is it appears that some bolts being torqued
have been overlooked and what is the chance that the cylinder nuts & thru
bolts had been overlooked also?

Simply, You don't know until you check. It'll require 10 minutes if you
have easy access to the engine.

Cylinders may run for a while but can start working on the crankcase, break
one stud then the others follow in quick succession then the cylinder
departs the engine.
Some instances it may appear that the connecting rod broke first to cause
the damage, but actually the cylinder left first and the rod broke after.

I don't have the link handy, but Sacramento Sky Ranch website has a bunch
of information.

Good chance that is just the spine bolts and you'll make TBO.

Take care

Kent Felkins

[Jay Honeck]

> The point I'm trying to make is it appears that some bolts being torqued
> have been overlooked and what is the chance that the cylinder nuts & thru
> bolts had been overlooked also?
>
> Simply, You don't know until you check. It'll require 10 minutes if you
> have easy access to the engine.

I'm having my shop check these this morning.

To those who think that the bolt might have been loose from the start,
remember: I watched the shop build this engine, and I personally saw them
check the torque on the engine case bolts. They *were* tightened to spec.

I also know that they never re-checked them, however, and my main mechanic
has admitted that they never check these as a matter of course.

In the case of the O-540, anyway, the case bolts are torqued surprisingly
low, and they are not secured in any way. No cotter pin, no safety wire, no
LocTite, no lock washer -- NOTHING prevents those nuts/bolts from loosening
over time. It seems like a ridiculous over-sight, but that's the way it
is.

A guy on the Cherokee Chat actually had a case bolt FALL OUT after loosening
over time from vibration, so this is not an unheard-of problem. I'm
surprised it's never been addressed in this forum before -- at least not in
my 7 years here.

I've bought a torque wrench, and I'm going to be checking ALL of these bolts
every time I change the oil, from now on.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Allen]

"Jay Honeck" > wrote in message
news:6q3Pd.63958$eT5.59714@attbi_s51...
> I've bought a torque wrench, and I'm going to be checking ALL of these
bolts
> every time I change the oil, from now on.
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"


You may want to check with your mechanic about this also. I think the proper
way to check torque of a bolt is to loosen it first and then re-torque.
This could lead to case-cracks after multiple sessions. The best method of
checking might be the "tamper stripe". Have your mechanic apply it after
torque and then just examine it at oil change.

Allen

[George Patterson]

Allen wrote:
>
> You may want to check with your mechanic about this also. I think the proper
> way to check torque of a bolt is to loosen it first and then re-torque.

Nope. Just buy a modern wrench, set it to the bottom end of the proper torque
range, and try to tighten the bolt. If the wrench "clicks" without the bolt
turning, you're good to go. If the bolt turns first, call that to the attention
of your mechanic.

George Patterson
He who would distinguish what is true from what is false must have an
adequate understanding of truth and falsehood.

[Trent Moorehead]

"Jay Honeck" > wrote in message
news:6q3Pd.63958$eT5.59714@attbi_s51...

> To those who think that the bolt might have been loose from the start,
> remember: I watched the shop build this engine, and I personally saw them
> check the torque on the engine case bolts. They *were* tightened to spec.
>
> I also know that they never re-checked them, however, and my main mechanic
> has admitted that they never check these as a matter of course.

Now, I am not an A&P, but is it possible that when the bolts were torqued
that they needed to be torqued in a particular order, reminiscent of
tightening lug nuts on a wheel? Sometimes when tightening several bolts, the
action of tightening later bolts causes the first bolt to become loose. In
this scenario, the last bolt is torqued correctly and the first bolt is
fairly loose. Just thinking here....

-Trent
PP-ASEL

[Jon Woellhaf]

Jay wrote, "I've bought a torque wrench, and I'm going to be checking ALL of
these bolts every time I change the oil, from now on."

Jay,

I'm sure you know this from your motorcycle Zen days, but I've learned (and
relearned a couple times) to be certain the click-type torque wrench setting
is correct before using it -- and to loosen it completely before putting it
away. (Maybe the latter is an old wives' tale.)

I've also learned to be careful to note whether foot-pounds or inch-pounds
is specified. It seems that aircraft bolts are often torqued considerably
less than I would expect them to be.

Regards,

Jon (not an A&P or even a motorcycle mechanic)

PS: I shall now be checking my engine's bolts. Thanks for the heads up!

[Orval Fairbairn]

In article <6q3Pd.63958$eT5.59714@attbi_s51>,
"Jay Honeck" > wrote:

> > The point I'm trying to make is it appears that some bolts being torqued
> > have been overlooked and what is the chance that the cylinder nuts & thru
> > bolts had been overlooked also?
> >
> > Simply, You don't know until you check. It'll require 10 minutes if you
> > have easy access to the engine.
>
> I'm having my shop check these this morning.
>
> To those who think that the bolt might have been loose from the start,
> remember: I watched the shop build this engine, and I personally saw them
> check the torque on the engine case bolts. They *were* tightened to spec.
>
> I also know that they never re-checked them, however, and my main mechanic
> has admitted that they never check these as a matter of course.
>
> In the case of the O-540, anyway, the case bolts are torqued surprisingly
> low, and they are not secured in any way. No cotter pin, no safety wire, no
> LocTite, no lock washer -- NOTHING prevents those nuts/bolts from loosening
> over time. It seems like a ridiculous over-sight, but that's the way it
> is.
>
> A guy on the Cherokee Chat actually had a case bolt FALL OUT after loosening
> over time from vibration, so this is not an unheard-of problem. I'm
> surprised it's never been addressed in this forum before -- at least not in
> my 7 years here.
>
> I've bought a torque wrench, and I'm going to be checking ALL of these bolts
> every time I change the oil, from now on.


Another caveat on torquing (from an old AI): All torquing should be done
"wet", with a drop of oil to lube the nut, so as not to get a false
torque reading.

[Allen]

"George Patterson" > wrote in message
...
>
>
> Allen wrote:
> >
> > You may want to check with your mechanic about this also. I think the
proper
> > way to check torque of a bolt is to loosen it first and then re-torque.
>
> Nope. Just buy a modern wrench, set it to the bottom end of the proper
torque
> range, and try to tighten the bolt. If the wrench "clicks" without the
bolt
> turning, you're good to go. If the bolt turns first, call that to the
attention
> of your mechanic.
>
> George Patterson
> He who would distinguish what is true from what is false must have an
> adequate understanding of truth and falsehood.

That will only tell you if the bolt is under-torqued. To make sure it is
torqued to a specific number it must be loosened first.

Allen

[Mark Hansen]

On 2/11/2005 11:01, Allen wrote:

> "George Patterson" > wrote in message
> ...
>>
>>
>> Allen wrote:
>> >
>> > You may want to check with your mechanic about this also. I think the
> proper
>> > way to check torque of a bolt is to loosen it first and then re-torque.
>>
>> Nope. Just buy a modern wrench, set it to the bottom end of the proper
> torque
>> range, and try to tighten the bolt. If the wrench "clicks" without the
> bolt
>> turning, you're good to go. If the bolt turns first, call that to the
> attention
>> of your mechanic.
>>
>> George Patterson
>> He who would distinguish what is true from what is false must have an
>> adequate understanding of truth and falsehood.
>
> That will only tell you if the bolt is under-torqued. To make sure it is
> torqued to a specific number it must be loosened first.

Additionally, I think the bolt can "stick" in place - which may
fool the torque wrench. Loosening the bolt before torquing it would
solve this problem as well.


>
> Allen
>
>


--
Mark Hansen, PP-ASEL
Sacramento, CA

[George Patterson]

Allen wrote:
>
> That will only tell you if the bolt is under-torqued.

And that is all Jay needs to know.

George Patterson
He who would distinguish what is true from what is false must have an
adequate understanding of truth and falsehood.

[Jon A.]

On Fri, 11 Feb 2005 14:36:50 GMT, "Jay Honeck"
> wrote:

>> The point I'm trying to make is it appears that some bolts being torqued
>> have been overlooked and what is the chance that the cylinder nuts & thru
>> bolts had been overlooked also?
>>
>> Simply, You don't know until you check. It'll require 10 minutes if you
>> have easy access to the engine.
>
>I'm having my shop check these this morning.

Good for you.
>
>To those who think that the bolt might have been loose from the start,
>remember: I watched the shop build this engine, and I personally saw them
>check the torque on the engine case bolts. They *were* tightened to spec.

New bolts, new nuts, new lock washers, torque wrench calibrated
recently?
>
>I also know that they never re-checked them, however, and my main mechanic
>has admitted that they never check these as a matter of course.

Tsk, tsk! What else do they not do?
>
>In the case of the O-540, anyway, the case bolts are torqued surprisingly
>low, and they are not secured in any way. No cotter pin, no safety wire, no
>LocTite, no lock washer -- NOTHING prevents those nuts/bolts from loosening
>over time. It seems like a ridiculous over-sight, but that's the way it
>is.

If all of the engines would have failed, they would have changed the
procedure. Something else is wrong.
>
>A guy on the Cherokee Chat actually had a case bolt FALL OUT after loosening
>over time from vibration, so this is not an unheard-of problem. I'm
>surprised it's never been addressed in this forum before -- at least not in
>my 7 years here.
>
>I've bought a torque wrench, and I'm going to be checking ALL of these bolts
>every time I change the oil, from now on.

Have it calibrated, and remember that each time you torque it, the
bolt stretches. Some years ago, when it was credible, AVWEB had an
article on torque. You can probably still pull it up.

[Jon A.]

On Fri, 11 Feb 2005 18:27:23 GMT, Orval Fairbairn
> wrote:

>In article <6q3Pd.63958$eT5.59714@attbi_s51>,
> "Jay Honeck" > wrote:
>
>> > The point I'm trying to make is it appears that some bolts being torqued
>> > have been overlooked and what is the chance that the cylinder nuts & thru
>> > bolts had been overlooked also?
>> >
>> > Simply, You don't know until you check. It'll require 10 minutes if you
>> > have easy access to the engine.
>>
>> I'm having my shop check these this morning.
>>
>> To those who think that the bolt might have been loose from the start,
>> remember: I watched the shop build this engine, and I personally saw them
>> check the torque on the engine case bolts. They *were* tightened to spec.
>>
>> I also know that they never re-checked them, however, and my main mechanic
>> has admitted that they never check these as a matter of course.
>>
>> In the case of the O-540, anyway, the case bolts are torqued surprisingly
>> low, and they are not secured in any way. No cotter pin, no safety wire, no
>> LocTite, no lock washer -- NOTHING prevents those nuts/bolts from loosening
>> over time. It seems like a ridiculous over-sight, but that's the way it
>> is.
>>
>> A guy on the Cherokee Chat actually had a case bolt FALL OUT after loosening
>> over time from vibration, so this is not an unheard-of problem. I'm
>> surprised it's never been addressed in this forum before -- at least not in
>> my 7 years here.
>>
>> I've bought a torque wrench, and I'm going to be checking ALL of these bolts
>> every time I change the oil, from now on.
>
>
>Another caveat on torquing (from an old AI): All torquing should be done
>"wet", with a drop of oil to lube the nut, so as not to get a false
>torque reading.

Let's hope the old AI isn't doing much any longer. Whether a bolt is
wet or dry (oil, locktite,graphite) will change the torque specs. The
manufacturer should specify the condition of the bolt for those who
have their JD's.

[[email protected]]

Gene Kearns wrote:
snip

> With reference to exterior case bolts, I am only passing along
> information given to me at both the Lycoming and Continental factory
> overhaul schools. I kinda thought they knew what they were talking
> about. But, WTF do *they* know? If you feel comfortable never
checking
> this, by all means, don't. It isn't specifically required by law.

And your point is what? I've allegedly spent 17 years maintaining GA
recips about 85%/15% Lyc/TCM, and have never been to a "factory
overhaul" school. During the last GA "factory" school I allegedly
attended, I had to explain to the "factory" TCM rep why he was getting
so many compliants concerning cold & hot engine starts on the Seneca V.

I can pretty much guarantee that I've allegedly hung, set-up and
maintained thru TBO removal more Lyc factory o-hauls, re-mans, and
probably new engines than any 15 owners that hang around in the
'groups. That does not take into account local o-hauls, other
name-brand o-hauls and customer aircraft that were purchased with who
knows whose o-haul is under the hood.

> >perspective of an alleged maintenance technician, so WTF do I know.
>
> If this is some kind of knee-jerk reaction to my reference to
> technician need-to-know, that was reference to knowledge and use of
> Lycoming SI 1112 and SB 272, not checking the exterior case bolts. In
> the instance of this particular engine running 500 hours (I think)
> with some bolts (how many others?) finger tight... I think it would
be
> a *great* candidate for checking for fretting corrosion by this
method
> set forth in the manufacturer's service information.
>
> However, since nobody wrote a specific law governing this, feel free
> to use that calibrated elbow, tighten everything up, and send the
> airplane to the flight line.... Hell, it'll be all right.....

If there was "some kind of knee-jerk reaction" it was to your statement
that it is common industry practice to either verify the
torque/re-torque case bolts at some periodic interval. That sir, is
bull****.

BTW, your shop pics are very impressive, perhaps some day I can take a
break from allegedly working full-time in somebody else's hangar on
somebody else's airplane, and have time to do something similiar.

TC

[Allen]

> Allen wrote:
> >
> > That will only tell you if the bolt is under-torqued.
>

George Patterson" > wrote in message
...
> And that is all Jay needs to know.
>
> George Patterson
> He who would distinguish what is true from what is false must have an
> adequate understanding of truth and falsehood.

Not if he wants it done right. Over-torque has it's own problems associated
with it, such as the bearing pinch someone eluded to earlier.

Allen

[Jon Woellhaf]

"Jon A." wrote, "Some years ago, when it was credible, AVWEB had an article
on torque."

Jon,

Do you feel that AvWeb is no longer credible?

Jon

[Jay Honeck]

<BIG snip of good stuff>

> If the only offending bolts were the top case bolts, then you are
> probably going to be just fine. I have seen this happen before and it
> was not the rebuilder's fault... it was the installer's..... for
> playing around with the "hang-point" for engine installation.

Thanks, Gene, for the good information.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Jay Honeck]

> I'm sure you know this from your motorcycle Zen days

*sigh* Some days I wish I'd stuck to motorcycles...

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[George Patterson]

Allen wrote:
>
> Not if he wants it done right. Over-torque has it's own problems associated
> with it, such as the bearing pinch someone eluded to earlier.

There's no way that a case bolt is going to tighten up further during a year of
use, so there's no reason at all to test for overtorqueing every year. All he
needs to test for is bolts backing out.

George Patterson
He who would distinguish what is true from what is false must have an
adequate understanding of truth and falsehood.