B model fuel tank OOPS fittings reverse thread?

Discussion for builders, pilots, owners, and those interested in building or owning a second generation Sonex or Waiex.

B model fuel tank OOPS fittings reverse thread?

Postby sjakulski » Mon Mar 28, 2022 5:17 pm

The fuel tank bulkhead fitting (and OOPS fittings) that I have use reverse external threads I note. The plan calls for a finger screen which I obtained from spruce (their “standard” fitting). However, it seems that the threads of the finger screen and the bulkhead fitting are not the same. Anyone else run into this issue?

Also, the plan calls for an AN915-6 elbow fitting connected to the fuel tank’s bulkhead fitting, which as mentioned uses reverse threads. Cant get the AN915 to thread either. But, I have not heard of the AN915 using reverse threads, nor dies its description say it uses reverse thread?? Am I missing something? Did Others have issues here?

Steve
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Re: B model fuel tank OOPS fittings reverse thread?

Postby racaldwell » Mon Mar 28, 2022 6:25 pm

Steve,

The internal threads are regular NPT pipe threads. The fuel outlet is 3/8" NPT. Only the large external nut and threads are left hand.

Rick Caldwell
Xenos 0057
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Re: B model fuel tank OOPS fittings reverse thread?

Postby sjakulski » Mon Mar 28, 2022 7:27 pm

racaldwell wrote:Steve,

The internal threads are regular NPT pipe threads. The fuel outlet is 3/8" NPT. Only the large external nut and threads are left hand.

Rick Caldwell
Xenos 0057


Yes, but the 45 degree AN fitting female end called for in the plan gets threaded onto the bulkhead fitting male end. The Bulkhead fitting is reverse thread…the AN fitting is not. Threads are opposite on these two.

And while the internal thread of the bulkhead may be a standard thread the finger strainer thread count seems to be different as it will not insert past the first thread…by hand force anyway.
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Re: B model fuel tank OOPS fittings reverse thread?

Postby racaldwell » Tue Mar 29, 2022 8:52 am

Steve,

I'd question Sonex on why they called out a female fitting to be installed on the outside threads of the oops fitting. That makes no sense to me.

Those outside threads are straight threads and would require an oring to seal. My oops fittings have a flat cut on the sides so it can be held steady with a wrench while the left hand nut is tightened. If yours has the flats, then there is no chance you would ever get a seal with a fitting attached.

Rick Caldwell
Xenos 0057
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Re: B model fuel tank OOPS fittings reverse thread?

Postby sjakulski » Wed Mar 30, 2022 11:01 am

sjakulski wrote:The fuel tank bulkhead fitting (and OOPS fittings) that I have use reverse external threads I note. The plan calls for a finger screen which I obtained from spruce (their “standard” fitting). However, it seems that the threads of the finger screen and the bulkhead fitting are not the same. Anyone else run into this issue?

Also, the plan calls for an AN915-6 elbow fitting connected to the fuel tank’s bulkhead fitting, which as mentioned uses reverse threads. Cant get the AN915 to thread either. But, I have not heard of the AN915 using reverse threads, nor dies its description say it uses reverse thread?? Am I missing something? Did Others have issues here?

Steve


Turns out that the call-out for fitting AN 915-6 on the plan (wxb-G01, in my case) is incorrect. Cost me days in delay waiting on that $30 fitting in the mail…now to spend more $$ to send it back to Spruce.
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