Oil Coolers

In October, after an extensive repair/restoration of my airplane, the
oil cooler split on start-up and dumped most of the oil. Long story, but
the engine seized up 6 minutes into the flight and we did an emergency
landing in the desert. We were very fortunate to walk away with minor
injuries, but the plane was totaled.

To the airplane owners out there, how often do you flush/pressure test
or replace your oil cooler? Some say it's only done at a major overhaul,
others say it should be done at every annual, others say only if there's
a problem w/oil pressure. I had never heard of an oil cooler failing
before this, but now I've heard people say it happens on occasion.

Anyone else here have experience with this?

Shirl

unicate wrote:
To the airplane owners out there, how often do you flush/pressure test
or replace your oil cooler? Some say it's only done at a major overhaul,
others say it should be done at every annual, others say only if there's
a problem w/oil pressure. I had never heard of an oil cooler failing
before this, but now I've heard people say it happens on occasion.

Anyone else here have experience with this?



I had an oil line to the oil cooler on a Piper Lance separate after an engine
overhaul, dumping the oil and causing the engine to seize just like your
description... about 5 or 6 minutes into the flight. The resulting landing in a
cow pasture did not go well.

As far as I know, it was caused by a mechanic not tightening the line; not
failure of the cooler itself.




--
Mortimer Schnerd, RN
mschnerdatcarolina.rr.com

unicate wrote:
To the airplane owners out there, how often do you flush/pressure test
or replace your oil cooler? Some say it's only done at a major overhaul,
others say it should be done at every annual, others say only if there's
a problem w/oil pressure. I had never heard of an oil cooler failing
before this, but now I've heard people say it happens on occasion.

Anyone else here have experience with this?

Mortimer Schnersd, RN wrote:
I had an oil line to the oil cooler on a Piper Lance separate after an engine
overhaul, dumping the oil and causing the engine to seize just like your
description... about 5 or 6 minutes into the flight. The resulting landing
in a cow pasture did not go well.

As far as I know, it was caused by a mechanic not tightening the line; not
failure of the cooler itself.

Right, the lines can come loose and/or fail, too, but mine was the oil
cooler itself -- you could *see* where it split, and 3 days later, at
the salvage yard, oil was still dripping out of it. I was later told,
"Oh yeah, those do that sometimes!" I also later learned that they're
supposed to be flushed and pressure-tested, but I can't seem to get a
definite answer from anyone as to when or how often this is supposed to
be done.

Thanks for your response.

Shirl

Depending on the design of the oil cooler, they should be
inspected and maintained on a regular schedule.

Common problems are oil congealing and blockage of oil flow
in cold weather, a by-pass valve should prevent oil
starvation to the engine. The oil cooler bursting problem
is often caused by the oil pressure regulator relief valve
being stuck on engine startup, oil pressure can go into the
hundreds or thousands of pounds pressure if the regulator
valve does not open at the pump.

The engine oil pump and regulator can produce more pressure
than the system can seal or contain if the regulator sticks
even momentarily.



wrote in message
...
| unicate wrote:
| To the airplane owners out there, how often do you
flush/pressure test
| or replace your oil cooler? Some say it's only done at
a major overhaul,
| others say it should be done at every annual, others
say only if there's
| a problem w/oil pressure. I had never heard of an oil
cooler failing
| before this, but now I've heard people say it happens
on occasion.
|
| Anyone else here have experience with this?
|
| Mortimer Schnersd, RN wrote:
| I had an oil line to the oil cooler on a Piper Lance
separate after an engine
| overhaul, dumping the oil and causing the engine to
seize just like your
| description... about 5 or 6 minutes into the flight.
The resulting landing
| in a cow pasture did not go well.
|
| As far as I know, it was caused by a mechanic not
tightening the line; not
| failure of the cooler itself.
|
| Right, the lines can come loose and/or fail, too, but mine
was the oil
| cooler itself -- you could *see* where it split, and 3
days later, at
| the salvage yard, oil was still dripping out of it. I was
later told,
| "Oh yeah, those do that sometimes!" I also later learned
that they're
| supposed to be flushed and pressure-tested, but I can't
seem to get a
| definite answer from anyone as to when or how often this
is supposed to
| be done.
|
| Thanks for your response.
|
| Shirl

Recently, Jim Macklin posted:

Depending on the design of the oil cooler, they should be
inspected and maintained on a regular schedule.

Common problems are oil congealing and blockage of oil flow
in cold weather, a by-pass valve should prevent oil
starvation to the engine. The oil cooler bursting problem
is often caused by the oil pressure regulator relief valve
being stuck on engine startup, oil pressure can go into the
hundreds or thousands of pounds pressure if the regulator
valve does not open at the pump.

The engine oil pump and regulator can produce more pressure
than the system can seal or contain if the regulator sticks
even momentarily.

Good info, Jim, thanks!

Now, I'll pay particular attention to the pressure on start-up to note
whether the needle is pinned for any duration.

Neil

If it happens it will be fast, faster than the gauge will
likely respond. The oil pump is a set of meshed gears that
move the oil. They move a fixed amount with each revolution
of the engine. There is a spring loaded pressure relief
valve in the pump that by-passed oil back to the pump intake
if the pressure is high.
Chapter 6 of AC 65-12
http://www.airweb.faa.gov/Regulatory...0?OpenDocument
has diagrams and explanations.


During an overhaul of an engine, a valve can become jammed,
blocked or otherwise adversely effected. The valves should
be clean and function checked. But a metal chip or other
problem can happen and can get into a pump system. Often
the relief valves are stuck open and you don't get full
pressure, but it can stick a valve closed and then the
pressure goes up until something breaks or a seal blows.



"Neil Gould" wrote in message
. net...
| Recently, Jim Macklin
posted:
|
| Depending on the design of the oil cooler, they should
be
| inspected and maintained on a regular schedule.
|
| Common problems are oil congealing and blockage of oil
flow
| in cold weather, a by-pass valve should prevent oil
| starvation to the engine. The oil cooler bursting
problem
| is often caused by the oil pressure regulator relief
valve
| being stuck on engine startup, oil pressure can go into
the
| hundreds or thousands of pounds pressure if the
regulator
| valve does not open at the pump.
|
| The engine oil pump and regulator can produce more
pressure
| than the system can seal or contain if the regulator
sticks
| even momentarily.
|
| Good info, Jim, thanks!
|
| Now, I'll pay particular attention to the pressure on
start-up to note
| whether the needle is pinned for any duration.
|
| Neil
|
|

To the airplane owners out there, how often do you flush/pressure test
or replace your oil cooler? Some say it's only done at a major overhaul,
others say it should be done at every annual, others say only if there's
a problem w/oil pressure. I had never heard of an oil cooler failing
before this, but now I've heard people say it happens on occasion.

Anyone else here have experience with this?

Our oil cooler failed on a flight to Missouri earlier this fall.
Luckily, it split in such a way (at a seam) that the oil was pumped out
SLOWLY, making a huge mess but not harming the engine. (We only lost
1/2 quart of oil on a 1-hour flight.)

I've never heard of anyone pressure testing an oil cooler, although I'm
sure it's done.

Glad you came out okay...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

In addition to JimM's great information, check out
http://www.oilcoolers.com/ , Pacific Oil Cooler Service. Lots of good info
there. If you get to OSH next summer, look them up. You'll be amazed at
how much crud can accumulate in your oil cooler.
JimB

Thanks for the link.



--
Merry Christmas
Have a Safe and Happy New Year
Live Long and Prosper
Jim Macklin
"Jim Burns" wrote in message
...
| In addition to JimM's great information, check out
| http://www.oilcoolers.com/ , Pacific Oil Cooler Service.
Lots of good info
| there. If you get to OSH next summer, look them up.
You'll be amazed at
| how much crud can accumulate in your oil cooler.
| JimB
|
|

Recently, Jim Macklin posted:

If it happens it will be fast, faster than the gauge will
likely respond. The oil pump is a set of meshed gears that
move the oil. They move a fixed amount with each revolution
of the engine. There is a spring loaded pressure relief
valve in the pump that by-passed oil back to the pump intake
if the pressure is high.
Chapter 6 of AC 65-12

http://www.airweb.faa.gov/Regulatory...0?OpenDocument
has diagrams and explanations.

Thanks, I'll look it over.

During an overhaul of an engine, a valve can become jammed,
blocked or otherwise adversely effected. The valves should
be clean and function checked. But a metal chip or other
problem can happen and can get into a pump system. Often
the relief valves are stuck open and you don't get full
pressure, but it can stick a valve closed and then the
pressure goes up until something breaks or a seal blows.

If the valve sticks closed, wouldn't the oil pressure gauge be "pinned"
high?

Neil