Fuel Leak from FT-60 (Red Cube)

[UnPossible]

Hey - I've ran my engine several time now, and have found a slow fuel leak at the FT-60 (Red Cube) fuel flow transducer.

I have removed the transducer and the nipples, cleaned everything up, goobered the fittings up with Permatex #2, and reassembled it a couple of times only for the leaks to remain.

The fittings only seem to leak when the engine is running. If I pressurize the fuel system with the fuel pump, I am not seeing any leaks.

I'm about 99% sure that I did not overtighten the fittings, as I just took them snub, they added about 1/2 a flat of additional rotation.

Does anyone have any idea as to what could be the problem?

Thanks,
Jason

[Bob Martin]

Is it leaking at the threaded connections?
What type fittings are you using, alum or steel?

[UnPossible]

Originally Posted by Bob Martin

Is it leaking at the threaded connections?
What type fittings are you using, alum or steel?

Steel fittings - leaking at the threaded connetctions going into the FT-60.

Thanks,
Jason

[TS Flightlines]

Jason----not likely, but look for a crack in the treads. The red cubes are alot thicker that the older transducers that would crack if you overtightened the AN fittings. Tighten them down. The NPT threads seal by the thread taper, so a good sealer is required.

Tom

[Walt]

From the install manual:

DO NOT EXCEED a torque of 15 ft. lbs. or screw the fittings tighter than two full turns past hand tight, whichever happens first.

[TS Flightlines]

Walt---I'm thinking Jason took them to snug and alittle bit, and doesnt have enough torque on the fitting. I agree with you.
Tom

[Pat Stewart]

I would start with the flares on the aluminum fuel lines.

Pat

[Walt]

Originally Posted by TS Flightlines

Walt---I'm thinking Jason took them to snug and alittle bit, and doesnt have enough torque on the fitting.Tom

That's what I was thinking too, most folks have a tendancy to under torque pipe fittings hence the torque for this comes in as a handy reference.

[UnPossible]

Originally Posted by TS Flightlines

Walt---I'm thinking Jason took them to snug and alittle bit, and doesnt have enough torque on the fitting. I agree with you.
Tom

Tom - I think you are right.... I think I was afraid of over Torqueing them... I took out the Red Cube and went out and bought a deep well 5/8" socket that will fit the fittings.

Looking at the instrucitons I have, they say not to torque over 25 ft lbs. I set my torque wrench for 25 ft lbs, and the fittings both spun a coupe of full rotations or more beyond where I had them before the torque wrench clicked off.....

Really hoping that this fixes my fuel drip issue..... guess we'll know tomorrow evening.

Thanks,
Jason

[N427EF]

A leaking nipple was the cause of my fuel smell issue in my RV-10.
The nipple was bottomed out in the red cube fuel meter and no amount of torque could seal the weeping leak.
I Pro Sealed it in, problem solved.