Some days you're just lucky!!

Twice in my flying carrier I have been fortunate enough to escape being in an airplane that had a very high probability of catching on fire. The first time was many years ago ferrying a Stinson L5 Sentinel. I had taken off after refueling a few minutes earlier when I noticed that my foot was wet. Looking under the panel I was shocked to see fuel running from under the panel and dripping in a steady stream onto my leg and shoe. I immediately killed the master to eliminate electrical as a source of ignition and immediately returned to the airport landing as carefully and quickly as possible. I was very afraid that the exhaust which terminated immediately below the fabric covered belly would catch the gas on fire. Fortunately all turned out well and a repair to the fuel selector solved the problem. Since that time I have always been extra cautious when doing anything with aircraft fuel systems.

Today I took the elderly friend, who introduced me to flight in small airplanes, for perhaps his last flight. Little did I know how close that statement almost became true for the both of us. After flying for about an hour, in which he piloted over 20 minutes, we landed and put the plane in the hanger. He was so happy and thankful for the flight opportunity that it made my day.

After seeing him off I returned to the hanger and as I approached the plane this is what I saw.



To say the least I was shocked beyond belief. I immediately de-cowled the plane to find the source of the leak. At first the source was not apparent however after turning on the boost pump fuel started spraying out of the fuel pressure source line where it attached to the fuel pump. After about a minute I had a two foot diameter puddle under the plane.





After removing the line I determined that the line had cracked under the B nut sleeve. Obviously a stainless braided line will be ordered Monday morning.



Lesson learned for me is that there is no place for copper tubing in a pressure situation on an airplane. I've had primer lines crack on certified airplanes in the past and should have replaced the darned thing before. My plane only has about 300 hours on it so I wasn't really all that concerned and was waiting to do it during a skyview upgrade I will be doing in a couple of months.

I was so lucky today as I was planning on a three hour trip this morning but cancelled to take my old friend flying. At no time during the flight did I ever smell gas nor have any idea there was a leak. Sometimes I guess good deeds pay off and the lord above takes care of us fools.

Now if someone will just tell me how to get the gas stains off the belly I will be most grateful.

Glad you are OK! That would have been bad!

X2. Man, what a find, and thanks for the aviation lesson learned.

The power of sharing.
You likely will never meet the aviator face to face... though you may have saved their life.

Glad that you're both okay and the plane too.

Lacquer thinner should clean it up, I think. Not certain, but it cleaned up a 100LL spill on my hangar floor one day. Don't know what it'll do to the paint, though, so test it somewhere first.

There are probably different brands with different ingredients. Mine probably came from Home Depot, but not certain.

Dave

Copper can work harden and crack.

Blue stains can be removed with a bit of gasoline on a rag, or mineral spirits usually work.

Greg

Yikes!

I'm about to build primer lines for my Lyc and now I'm not sure what to do. We will see.

To clean fuel stains, exhaust stain or ANY stain on the belly, use GOOP, mechanics waterless hand cleaner. Safe and effective. Easy on hands and paint and not a fire hazard.

CC

comfortcat said:

I'm about to build primer lines for my Lyc and now I'm not sure what to do. We will see.

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Primer lines are only pressurized when you are priming the engine, so the amount of fuel that would leak from a crack is very low. Lines to the fuel pressure sender are pressurized the whole time either the boost pump or engine is turning, so the amount of fuel that can leak is very high.

Interesting to me as I work on my rsa fuel injected airplane. I have braided steel over Teflon everywhere except from the fuel distributor to the injectors, which are copper lines with as silver soldered ball end like a primer line.

Has anyone used a flexible line in this application?

The primer lines that came from the Lycoming factory on my O-320D2A are copper.

I always thought that fuel lines from the spider to each injector were stainless steel.

walkman said:

Interesting to me as I work on my rsa fuel injected airplane. I have braided steel over Teflon everywhere except from the fuel distributor to the injectors, which are copper lines with as silver soldered ball end like a primer line.

Has anyone used a flexible line in this application?

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Just a point of clarification here before everyone gets confused and goes off on a tangent. The line that cracked was the fuel pressure sense line that connects the mechanical fuel pump to the manifold on the firewall where the pressure sender is located. It was a copper line that had two vibration loops and was well supported. Usually copper lines tend to crack at the flare but in this case it cracked under the sleeve. I have seen these lines crack before and that is why I was intending to change it out in a couple of months. Primer lines will crack also but they are not under pressure except when in use. Normally the service life of the primer lines is very satisfactory and they can be found on your pipers, cessnas etc. I did not build my plane and this item was a concern but I thought that with the planes low time it would not be a problem until I changed it out.

My point to bringing my story to you is that copper or nylon lines have no place in this type of application. Primer lines ok pressure lines no way. They can cause you great harm if you are not as fortunate as I was. Fuel was spraying out on the accessory case and running down the hot exhaust. What kept the thing from catching on fire is beyond me. I'm so fortunate that I postponed my trip as a fire at 10,000 feet would have been the end of me. The good lord was looking after me today.

PS. MEK took the stains right off. Thanks for the hints.

MEK

MEK would not be a good choice on paint.
MEK will take everything off. I guess you got lucky and did not leave it on very long. Mineral Spirits or gas would most likely have done the trick and not harm the paint.

About primer lines, I've had 3 breaks over the ten years I had my -4 and upgraded the lines with SS injection lines and flew for 2-3 year before selling.
Problems solved as far as I know.


Glenn Wilkinson

I would not use any "hard" line from the engine to the firewall; too much vibration.

If you have anything other than braided lines from your engine to the firewall, you are holding a ticking time bomb with a short fuse. This is no reason to wait, change them now or ground the airplane. I am scratching my head on why you waited.

End of safety manefesto.

Ted,

Thanks for reporting this event and the obvious reason it happened.

It is remarkable that there are airplanes flying today with hard lines between firewall and engine - there have been many failures with this installation.

Seems like old habits won't go away even though they are really dumb.

Yes you were very blessed and as far as the blue stain don't worry about it sun light will take care of it. My blue stains vanished in just a couple of weeks.
G.P.

gmpaul said:

Yes you were very blessed and as far as the blue stain don't worry about it sun light will take care of it. My blue stains vanished in just a couple of weeks.
G.P.

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It seems like he would have to spend a lot of time flying upside down for that to work