without alot more and accurate data, it starts to look like a line/operator issue.
I'm not on a Lyman witch hunt but I would add that in all my travels I have never seen better maintained aircraft than those in Japan. I haven't worked for JAL but the other team certainly puts a good number of major players to shame and I've got no reason to think JAL aren't just as fastidious. Working for the Japanese has its challenges in certain areas but maintenance has never been one of those.
We'll now find out the valve manufacturing company is Japanese but I never said they were perfect
