Punctured oil line (almost!)

[SpamPilot]

Wondering if anyone else has seen this or has an understanding of the issue...

 

I had removed the cowl on my '68 M20F to do an oil and filter change.  Fortunately I was dawdling and in no particular hurry to complete this awkward and messy job.  I gave my engine a good lookover and noticed that the firesleeve over one of the lines going to the oil cooler was torn open at one point.  How could that happen?  Then I noticed the culprit.  There is a SCAT hose feeding the heater shroud running near this oil line with about an inch of clearance.  It appears the oil hose has been beating against the SCAT hose for a long time, presumably due to vibration.  The spiral wire in the SCAT hose had broken, leaving two polished and needle-sharp ends pointing at the oil line.  These dug through the firesleeve.  The only thing preventing the wire ends from chewing their way rapidly through the oil line itself was the steel braid armor over the oil line.  One strand of the armor was indeed broken, not enough to permit a puncture, but obviously it was only a matter of time.

 

I normally don't give much thought to SCAT hoses.  In the future, I will.  Needless to day, I took it straight in to my A&P to have the oil line and SCAT hose replaced.

 

My question is: does the vibrating oil line signify anything serious?  Or does it simply need to be tied down better?  Oil pressure is totally normal and the gauge doesn't indicate any vibration.  The oil cooler on this F-model is in the original location on the cowl and has not been relocated J-style.

 

 

 

[Guest]

Not at all un-usual, airplane engine compartments are high vibration areas. Any item poorly secured will rub on something, causing wear and damage. Adel clamps and lacing cord are your best friends, avoid nylon Ty raps particularly on metal surfaces. I've seen a Ty rap rub an engine mount to the point of requiring a welded repair.

Clarence

[N201MKTurbo]

To make you feel better try cutting one of those oil lines with a hack saw some time. They are amazingly tough.

 

A scrap one of coarse.

[47U]

Chafing is insidious.  EVERY TIME your cowling is off, take a look good around for things amiss. 

 

My airplane came with a fresh oil change when I bought it in 2008.  My first annual just happened to come due before my next oil change, which I would have done myself.  When I pulled the cowling off for the annual, I wondered what that red RTV was on the #2 rocker box oil drain line... Someone (#$%^&) had sealed up drain line with a hole chafed clean through the tubing wall.  Good grief... how long before it vibrates a crack in it and it just snaps in half?  I don't think a little RTV would fix that.  Found one similar on the right side, too.  

 

 

[kerry]

That red RVT repair is nuts!  Any pilot or mechanic with 1/2 a brain would know the proper repair would have been duct tape. lol

[DaV8or]

It seems there is always something trying to rub a hole in something somewhere. Seriously, not a lot of engineering thought went into securing hoses, wires and cables in our planes. Over the years mechanics adjust and change them and new equipment gets added. Chaffing is like oil leaks. A constant rock to push up a hill...

[robert7467]

Also look at your oil return tubes and make sure they are not rubbing against baffling. Ours got a pinhole leak and we brazed it for repair. With the top of the baffling off, the new brazed tube fit perfectly, when I installed the top baffling, through one of my triple checks, I noticed the tube was against the baffling again. This could have been a a serious issue if we didn't catch if, or if we flew the plane for an additional 5 or 10 minutes. Be careful, and always inspect your airplane, especially after someone works on it. 2, sometimes 3 sets of eyes on it never hurts.

[1964-M20E]

Chafing is insidious.  EVERY TIME your cowling is off, take a look good around for things amiss. 

 

My airplane came with a fresh oil change when I bought it in 2008.  My first annual just happened to come due before my next oil change, which I would have done myself.  When I pulled the cowling off for the annual, I wondered what that red RTV was on the #2 rocker box oil drain line... Someone (#$%^&) had sealed up drain line with a hole chafed clean through the tubing wall.  Good grief... how long before it vibrates a crack in it and it just snaps in half?  I don't think a little RTV would fix that.  Found one similar on the right side, too.  

Just repalced my #2 return line for the same reason.  Good catch.

[N601RX]

Wondering if anyone else has seen this or has an understanding of the issue...

 

I had removed the cowl on my '68 M20F to do an oil and filter change.  Fortunately I was dawdling and in no particular hurry to complete this awkward and messy job.  I gave my engine a good lookover and noticed that the firesleeve over one of the lines going to the oil cooler was torn open at one point.  How could that happen?  Then I noticed the culprit.  There is a SCAT hose feeding the heater shroud running near this oil line with about an inch of clearance.  It appears the oil hose has been beating against the SCAT hose for a long time, presumably due to vibration.  The spiral wire in the SCAT hose had broken, leaving two polished and needle-sharp ends pointing at the oil line.  These dug through the firesleeve.  The only thing preventing the wire ends from chewing their way rapidly through the oil line itself was the steel braid armor over the oil line.  One strand of the armor was indeed broken, not enough to permit a puncture, but obviously it was only a matter of time.

 

I normally don't give much thought to SCAT hoses.  In the future, I will.  Needless to day, I took it straight in to my A&P to have the oil line and SCAT hose replaced.

 

My question is: does the vibrating oil line signify anything serious?  Or does it simply need to be tied down better?  Oil pressure is totally normal and the gauge doesn't indicate any vibration.  The oil cooler on this F-model is in the original location on the cowl and has not been relocated J-style.

I relocated my oil cooler a couple of years ago.  The kit comes with new hoses and you get rid of the long hoses that go down by the exhaust.  It also saves a few pounds.  Since your needing a new hoses anyway, now might be a good time to consider it.