Oil leak on top of the engine

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"

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

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

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!

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

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"

"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

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.

"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

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!