Fuel Return line leak

The hose connection is leaking at the banjo fitting. There is a tight 90 degree bend on that line, and it has a lot of stress on it. I've made a temporary fix, but I need to order a new line. Anyone else have this issue?? Actually, it was not easy to find. It only leaked when the engine was running. Just running the electric fuel pump with the top cowl off did not show the leak. My guess is that vibration played a part. I did notice a small fuel stain on the belly. Running it with the cowl off was not a lot of help, as the prop wash distributed the fuel in a fine mist on the windshield, but I finally tracked down the source. I wonder how long this has been going on?? Maybe I just got a defective hose.

Tom

todehnal said:

My guess is that vibration played a part. I did notice a small fuel stain on the belly.

Click to expand...

Repeated disassembly can cause problems here also.

Rotax specifies that the copper seal washers be replaced every time it is disassembled.
A particular factor at this location is that there is a banjo bolt threading in from both directions. If the copper washers get overly crushed the two bolts contact each other. If this happens, the washers doesn't get crushed and begin to leak.

Is it leaking at the banjo bolt connection, or the hose/stem crimp?
Tom

The banjo fitting has never been separated since the original build, and does not leak. My leak is from the hose, where it was clamped to the fitting on the right end of the banjo fitting. My guess is that this clamp is a weak spot and that the 90 degree bend in the hose at that fitting takes it toll on the clamp, or, I got a bad clamp job from the start. I'm not familiar with these hose clamp. I can tell you that if it were an Aeroquip fitting, you could probably hang the engine by it, and it still wouldn't fail. Oh well.................

Tom

The hose of which you speak has been updated.
I think it is available under the same part number, as a complete assembly (banjo fitting, fuel pressure hose and fuel return hose).
It is a smaller diameter hose overall with better quality crimps.

rvbuilder2002 said:

The hose of which you speak has been updated.
I think it is available under the same part number, as a complete assembly (banjo fitting, fuel pressure hose and fuel return hose).
It is a smaller diameter hose overall with better quality crimps.

Click to expand...

Thanks Scott, I'm glad to hear that. I must not be the only one experiencing this problem. So, I guess I need to order a new line, and scrap the old one, unless there is a trade in being offered?? I'll also order a couple of the banjo fitting gaskets, and start fresh.

Tom

As has been mentioned on some other threads, TSFlightlines, and Aircraft Specialty engaged in a joint initiative to create a conductive teflon hose retrofit kit a few years ago.

As builders, Tom and I LOVE doing these kinds of projects. Also, I know that I am always interested in how components are fabricated. So, we have some videos of hose fabrication on youtube.

The video link below shows how the hoses are crimped, and also shows the pressure testing of the hoses. The RV-12 hoses are going to run at less than 10 psi. The hoses are tested to 2,000-3,000 psi. Their burst pressure is around 10,000 psi.

For those of you who are interested, here is the video link.

https://www.youtube.com/watch?feature=player_embedded&v=Rme_vMxjtN4

Thanks for your continued support, and happy building/flying.


Steve

I sure am glad that Steve is good at doing videos----I'm not!!
We're working on several more, as time permits.
Alot of stuff happening all at once!
Tom