Fuel Selector Valve

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David Barrett
Posts: 3
Joined: Fri Aug 27, 2021 6:30 pm

Fuel Selector Valve

Post by David Barrett »

I'm having a chronic problem where I have a fuel seep from the fittings
on the fuel selector valve on my falco. A few years back, I replaced the
original valve with the newer version. The current fittings still appear
to be seeping.

I've been looking over the plans, but I don't see any drawings or part
specifications for the valve or its fittings. I'm seeking information
from other falco owners about their fittings.

Mine appears to have three aluminum fuel tubes connecting to the fuel
lines, each with a ferrule and a nut (with "crawford" on it). The nuts connect
to a male-to-male pipe fitting which threads into the female threads on the
fuel selector. The fittings appear to have some sort of thread locker/sealer
applied at the selector joint.

One seep appears to be on the top of the pipe fitting. I'm not sure where the
other fittings seep; is it at the ferrule, or the fitting threads?

In the past, I found fuel lube thread sealer worked for the fuel flow transducer
fittings, but that won't help of the problem is at the ferrule. Are they swagelok
and can they be reattached differently if that is the source?

I've now drained all fuel out of the aircraft and am considering what to do.
Not sure whether to replace the fittings, ferrules, tubing etc. Any suggestions?

Dave Barrett
Alan Evan Hanes
Posts: 21
Joined: Wed Jul 28, 2021 6:41 pm
Location: Johannesburg South Africa

Re: Fuel Selector Valve

Post by Alan Evan Hanes »

Welcome Dave. You and your dad have a lovely plane.

If I am not mistaken the original fuel valve was just an off the shelf brass three way valve that was standard to nearly all homebuilt's at the time. I suspect it is a Weatherhead 3/8"FEM X3/8"FEM 3-PORT Valve (See Aircraft Spruce and Specialty Part# 05-01032). The fuel seep is probably caused by a broken line (assuming it was tightened sufficiently and its not leaking due to loose nuts) and itself most probably caused by over tightening.

I would not buy anything just yet. You might not need to replace anything if you disassemble the lines and apply Locktite thread sealant (its a white goo about USD 25 for a toothpaste size amount!). Whatever you do DO NOT USE PTFE Tape. Reassemble and make all joints just tight enough. Too tight cracks the lines.

Replacing the lines will be hard work. If you do have to replace the fuel valve, throw away the one you have and replace it with an Andair part suitable for your plane. It will be worth every cent. They will make a custom faceplate for you with Front/Rear/Off instead of the standard Left/Right/Off.

I know of at least one fatal accident due to PTFE tape. A really beautiful Sonex was built by Eddie, a Porsche mechanic, using a Porsche engine. Every tiny bit of the aircraft was exemplary. But this was his first exposure to aircraft. On his first flight in it with an instructor/test pilot the engine stopped. They almost made it back to the field but stalled in trying to stretch the glide killing both. A detailed teardown found a tiny bit of PTFE tape had made its way past all the filters into the carb. RIP Eddie Pallidin and Chris Twyford.
Get there fast to take it slow
Alan Evan Hanes
Posts: 21
Joined: Wed Jul 28, 2021 6:41 pm
Location: Johannesburg South Africa

Re: Fuel Selector Valve

Post by Alan Evan Hanes »

Locktite 577
Get there fast to take it slow
David Barrett
Posts: 3
Joined: Fri Aug 27, 2021 6:30 pm

Re: Fuel Selector Valve

Post by David Barrett »

Attached photo shows 3 fuel selectors
Top: Original kit part
Bottom Right: My selector replaced with new kit version
Bottom Left: Eaton Weatherhead 6749 1/4" NPT from AC Spruce

The handle position of the 6749 is different from falco:
Front tank: falco handle is up, 6749 handle is left, point right.
Rear tank: falco handle is right, 6749 handle is up, point down.

The flat on the 6749 shaft is rotated 90 degrees clockwise from the Falco shaft.

I received two 6749s from AC spruce, and they both were too hard to turn.
Attachments
3 Fuel Selectors
3 Fuel Selectors
3FalcoSelectors.jpg (119.16 KiB) Viewed 11233 times
Alan Evan Hanes
Posts: 21
Joined: Wed Jul 28, 2021 6:41 pm
Location: Johannesburg South Africa

Re: Fuel Selector Valve

Post by Alan Evan Hanes »

You will not like the answer but I strongly suggest spending the money and getting an Andair unit. I have yet to hear any objections to their products other than their price - you get what you pay for. It is really not worth buggering around with fuel in the cockpit surrounded by electrics. DO it properly and do it once. You will soon forget the price but not the quality.
George Richards and Rob Phillis both used them successfully that I know of, maybe they will be able to provide exact specifications of a replacement unit.
My investigation appears to show that they are cheaper direct from Andair and you can get the faceplate engraved with FWD 80L AFT 72L or anything you wish.
Get there fast to take it slow
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