Threads on NPT are not always made with single point threading tools. Often they are made a tool that cuts all the threads at once. Since the feed rate can be high, when it stops rotating, it can leave what looks like a parting line along the length of the threads. I always inspect NPT threads for this defect. I found it on an air system installation. I began checking about 10 joints in and they all leaked. I ended up chasing internal and external threads on about 140 joints, but none leaked, and still don't 23 years later.
I have not found parts for my 7 like that yet, but still check.
Good luck.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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