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Gasoline pouring onto the ground


opticsguy

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What freaks me out is that I have to turn off the engine to shut the fuel valve,  meaning that that leak would continue for about 2 minutes (how long it took to stop on the ground).  If I could have shut the fuel off and ran the engine until it stopped, I possibly could have starved a fire.

 

I'll take a stopped engine over a fire any day of the week, even (especially!) in flight.

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  • 1 month later...

I finally got back to Wisconsin and noticed fuel in the drip tray on the opposite side.   Sure enough, both pins were leaking.  I plugged them with expoxy, did a high speed run, and no leaks.  These two had been leaking for almost 3 years and my mechanic at the time didn't find them.

 

To add insult to injury, my D100 backlight went out, so I couldn't fly.

 

So far, I've got 3 out of 4 pins leaking at 9 years, and a catastrophic failure at 10.  I would think the FAA would be interested in this.

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Rotax and the FAA would say are you inspecting your carbs every 200 hrs and have you had them overhauled in 9 years. Many parts have life expectancies and not all are 2000 hr. TBO's.

These are very easy to foix. Just remove the loose pin, clean the end and hole with lacquer thinner and use Loctite 648 and press them back in place. This is one reason you are supposed to have drip trays. Anything on the carb that has fuel could leak under the right circumstances.

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If the pins are supposed to be glued in, then Rotax should issue a SA on that.  If carb bowls aren't inteded to last more than 5 years, they should be a replacement item so many hours or years.

 

I filled out a form with Rotax and have heard nothing.

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Rotax and the FAA would say are you inspecting your carbs every 200 hrs and have you had them overhauled in 9 years. Many parts have life expectancies and not all are 2000 hr. TBO's.

These are very easy to foix. Just remove the loose pin, clean the end and hole with lacquer thinner and use Loctite 648 and press them back in place. This is one reason you are supposed to have drip trays. Anything on the carb that has fuel could leak under the right circumstances.

The problem is not the difficulty in repair, it's the volume of the leak. My drip tray overflowed and spilled gasoline all over the engine, I'd bet a quart or two. I don't believe the carb overhaul specifically mentions checking the pins, or any spec for doing do. My carbs have less than nine years on them anyway.

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  • 2 months later...

This topic caught my attention! I think I understand what going on with the pins and them vibrating loose and dislodging out of there mounts leaving a hole in the bottom of the carb!

 

I need to address this issue. Can I dab epoxy on my finger and squeeze it up into the hole while the carbs are in position? Would squeezing locktight 648 from the tube be better fighting gravity and all?

 

Is there room to do this with carbs in position?

 

Thanks folks!

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This is rare and is usually caused by people rough handling the carb bowls and or not doing carb syncs and causing excessive vibration, warming up at too low an rpm,  anything that causes excessive vibration.

 

You can put a drop of epoxy on the underside of the pin hole, but the carb will overflow and just come out the vent. the result for masny will be the same IF you don't have the Rotax aluminum airbox where the vent tubes go back into the airbox. Putting epoxy on the bottom is more or less a feel good thing. If a pin ever did come out just put it back in place with some Loctite 648.

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All due respect to Roger, whose opinion I surely respect on this stuff...

 

The failure mode in my case (and at least a couple others I'm aware of) was that the pin worked loose, but stayed in place.  The floats continued to work normally.  In that case, epoxy on the holes would have stopped a leak altogether or at least slowed it to a drip.  No fuel would have come out the vents because the floats were working.

 

In my opinion, the epoxy can never hurt and in what seems like about half the cases it could make a difference between a huge leak and a tiny leak or none at all.  It's cheap insurance.

 

My understanding is that the new float bowls have blind drilled holes, which if true sure seems like a tacit admission by Bing/Rotax of an issue with the original design... 

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Hi Andy,

 

I never take offence to any debate or difference of opinion. I'm always a happy camper.  :giggle-3307:

 

My only concern is that someone doesn't think this is a cure all solution. If the fuel can't come out one place it will find another. One way to help combat this is if you take the bowls off tap the pins down and in the rare case this might happen it may prevent the pin from ever coming out.

 

p.s.

Don't bend that darn pin.  :fainting-1344:

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