Piper Cherokee oil Leak?

jmarine225

jmarine225

Pre-takeoff checklist
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Jmarine225
Ill try to get a photo to upload but I found, what appears to be an oil leak, maybe. I'm not sure what is leaking so I'll try to describe as best as possible. There is an oil line I believe, on the left (pilot) side of the aircraft, where the oil line connects to copper type tubing which goes into the firewall. The junction between the copper type tubing and the the Type C oil line has approximately a drop or two of oil, I believe on it. Any clue what this line is which connects to that copper tubing? It's going in for repair next week but I'm curious on it in advance. It's only a drop or two on the joint after flying but I know a small leak turns into a large leak at some point, yet doesn't repair itself.
 
Not intimately familiar with the Cherokee's setup (and it could well have changed in the 45 or 50 years since she was built), but what you describe sounds very much like it may be the line to the oil pressure gauge. If so, likely has a restricted coupling such that it won't leak you out of oil, but such leaks are a definite irritant (ask me how I know).
 
SCCutler said:
Not intimately familiar with the Cherokee's setup (and it could well have changed in the 45 or 50 years since she was built), but what you describe sounds very much like it may be the line to the oil pressure gauge. If so, likely has a restricted coupling such that it won't leak you out of oil, but such leaks are a definite irritant (ask me how I know).
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Thanks. Yeah its a 69, Cherokee 140. With the fear of being berated by a few, lol, I was curious if it's flown with this extremely minor leak, can it get larger to the point the line blows off, etc. blowing all the oil out. I figured it would be that line as it feeds into copper, then through the firewall.
 
Assuming I'm correct (and from your description, think I am), it very unlikely to blow off and, if it did, it would take a Very Long Time to bleed out.

Edit: Post a picture, if you can.
 
Don't fly it until it's fixed. Copper lines are famous for work-hardening due to vibration, and they start cracking and leaking. Then they suddenly break and all the oil is pumped overboard. Besides being a fire hazard, the engine soon seizes solid and you are in trouble. The flare on the copper line, inside the fitting, might be cracking.

I had a copper line do that to me in flight. There was one quart left when I landed. Another airplane I know did the same thing, but he wasn't so lucky. It seized and he deadsticked it into a field.

The manufacturers stopped using copper lines along time ago for just that reason.

Cessna uses a copper-coated steel line for their primer lines. It looks like copper and some mechanics have made the mistake of replacing it with copper. Not the same thing at all, and the copper fails.After it's busted, you prime the engine and spray fuel all over it. Sounds good, no? One little spark....
 
I’m always finding the Oil Pressure Line on Pipers with mfg date going back to the Reagan or possibly the Jimmy Carter era. They are not cheap and folks are reluctant to replace a hose that’s “ working fine”.
 
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Magman said:
They are not cheap...
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They're expensive until they fail. Then they look real cheap as the airplane catches fire or the engine quits in flight. Real cheap.
 
The “ restricted orifice” referred to is about .015 ID. Failure of the line or gage

will result in a slow dribble IF it is installed. Most of the modern aircraft use a

fitting in the case with the orifice. Many exp and older aircraft have had the

special fitting replaced with a standard fitting.


I’ve seen several failures including one directly over Niagara Falls. The ones with

the orifice were annoying but the outcome was ok. The one w/o did not have a

happy ending. He did not go alone too.

Modifying a standard fitting to include an orifice is a Minor Alteration in my book.

There are several ways it can be done. Whether regulations require it or not you

should know it could keep you and your pax alive.
 
Had an AP look at it. It’s the switch going to the Hobbs meter. Said it has the oriface where it can’t blow off causing a major leak. It will continue to ooze a drop or so every so often. Part has been ordered. Thanks for insight.
 
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There has been plenty of debate about that orifice fitting. Is it to reduce the flow in case of a line failure? Or is it to damp out the pulsations from the pump?

In any case, a tiny hole, with the oil pressure of a Lycoming behind it (up to 100 psi) will squirt hot (and therefore low-viscosity) oil out of it real quick. It's NOT going to just dribble. If the line fails right at the fitting, that tiny hole will even atomize it some, making for an explosive environment in the engine compartment, what with red-hot exhaust at high power settings, sparks at the brushes and slip rings in the alternator, sparks in the ventilated magneto distributors, and so on. Oil is flammable, after all, and once a pressurized-oil fire starts, even a windmilling prop will drive the engine and its oil pump and keep feeding the fire. Not a pretty situation at all, and completely avoidable.

There is no excuse whatever to let such a leak continue. It's not a gasket or shaft seal that have little more than atmospheric pressure against them. It's under considerable pressure, and it needs to be fixed. If it has anything to do with a copper line or ancient seeping hose, it's a threat. This isn't a car where you can screech to a halt and jump out.

https://www.aopa.org/training-and-safety/students/flighttestprep/skills/aircraft-fires
 
I think the restrictor orifice serves both purposes mentioned but mostly as a limiter on a hobbs pressure switch that closes at 4 psi?
I think pipers switch's are forward of the firewall but I can't remember for sure? Leaking oil is never a good thing especially up near the engine.
The switch on my 172N is under the panel inside on mine. I found it wet with oil during a annual a few years ago and it was replaced. Pretty easy job and not that expensive at the time.
 
“ Dribble” was not the best choice of words.

My intent was NOT to imply that it was safe to fly with a defect.

It was about “ buying” .

The O-200 has about 30 psi oil pressure.

The “ Niagara Falls “ failure allowed the pilot to “ buy time “ to fly to a nearby

airport and land after losing about 1 quart of oil.

One other O-200 powered aircraft w/o the orifice bought the farm

after the engine seized.



The Oil Pressure Switches have been with us for 50 + years. The later

installations tend to be better. Often early installs used switches that were

not designed for the task. Often they were screwed directly into an engine port

where they were susceptible to heat and vibration that caused failures.
 
Dan Thomas said:
There has been plenty of debate about that orifice fitting. Is it to reduce the flow in case of a line failure? Or is it to damp out the pulsations from the pump?
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Gary Ward said:
I think the restrictor orifice serves both purposes mentioned
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FYI: The orifice has been a certification requirement since the CAR days to prevent/limit excessive flammable fluid leaks if an instrument line fails. Its only required for indicating systems under pressure with the orifice installed at the pressure side of the line. Can't post links at the moment but will later if interested. As for system pulsations the go to device is a snubber or the poor man's version is to induce an air bubble at the indicator which will soften the oscillations for most fluids.
 
Aircraft Hose may look nice and “ work fine” but should actually be replaced.

Since replacement of prefabricated hoses is Preventative Maintenance and could be done by the owner the

question is ; “ Why are they not replaced”?

My guess is few people know the basics of hose evaluation.

I’ll take a shot at it.

In addition to the pressure rating a significant concern is the Hose Type.

Type C - 250 degrees Generally replaced about every 8 years but that also varies with the mfg.

Type D - 450 degrees. No life limit but still needs regular inspection for condition.


The other factor is AGE.

This may not be apparent when reading the tag.

A cell phone camera and blowing up is great for old guys. Like me!

A tag bearing “ 3Q13” would have been mfg. or pressure tested in the 3rd Quarter of 2013.

Easy!

You may find a hose that is actually considerably older than the aircraft.

Some folks install items that others threw out due to age.


So far I’ve seen 2 Cherokee Oil Cooler hoses fail in flight. An AD addresses this.

The other hose that concerns me comes up between the cylinders and goes to the Flow Divider on injected Lycomings.

Finding OLD Type C hose that is spraying fuel is a shocker.

It had to be doing it in flight!
 
Electronics International offers a temp/pressure gauge with transducers, harness and hardware for less than $600. Get rid of the oil line entering the cabin.
 
Timbeck2 said:
Electronics International offers a temp/pressure gauge with transducers, harness and hardware for less than $600. Get rid of the oil line entering the cabin.
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The transducer still mounts on the firewall to avoid the vibration and heat, so a hose is still involved.

Getting rid of oil and fuel (under pressure) from the cabin is a good idea, but there are still plenty of fuel (and sometimes high-pressure hydraulic) lines in the cabin that pose a threat simply because many seldom or never get inspected.
 
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