See, if we don't have a standard to comply to on the pilot level, how can we as pilots be held to that standard. Sure there might be a wear limit on an item, but unless we know the limit, we cannot determine it's airworhiness or not. It's totally subjective, what might not be frayed to me might be frayed to somebody else. Who is right or wrong? You can't just throw a blanket statement That the aircraft is unairworty due to a seatbelt that doesn't have a fray limit. I wouldn't stand for that crap on a ramp check it's completely ridiculous. Now if a seatbelt broke, we would have to comply with our MEL to take appropriate action to defer it(if we could). But if there is no technical information regarding the fray limit on a seatbelt, or any item for that matter then we can't possibly receive a pilot violation for it.
You've got it backwards, unfortunately. If there's no technical information regarding the acceptable fray on a seatbelt, then, technically,
no fray is acceptable. That's the way it works.
In the case of a seatbelt it becomes a judgement call. There is a standard, it's just not a standard that's easy for you to apply. TSO C22f says that the belt has to be able to withstand a certain load, I can't remember exactly what the load is or how the test is performed, 3000lbs comes to mind. I will tell you this, we used to try to send the belts that had lost their tags in to get recertified, but we quit because they aren't expensive enough to go to all that trouble, and whatever shop you send them to doesn't want to recertify someone else's belts, or their own belts for that matter, so they almost never pass.
In light that some people thought I was being adversarial (and I can see where they would think that). Here's how I look at it. If the belt has a few fuzzies but is generally intact, my judgement tells me that it would pass a test, to a point. If the belt looks like it came with the airplane and the airplane is a 1960 model, I'm gonna call it out (Cessna now life limits their belts to 10 years, a little excessive I think, but you know, lawyers...).
If there are any hanging threads (hard to describe... like parts of the belt where the web is no longer intact and it's just a curtain of threads), tears, slices, stitching falling out on the buckle loops or anything like that, I don't believe it would pass, and it needs to be replaced. Will some of the belts that I call out pass? Maybe... but in a case where you can't be sure, it pays to be conservative.
A belt with a missing or unreadable TSO tag is unairworthy, period, so be a nice pilot to your maintenance folks and protect those tags, please. I hate having to replace a perfectly good belt because someone squashed the tag in the seat frame and it's damaged and unreadable.
I just want to reiterate... I think that violating someone and giving a 709 ride for what you describe is over the top, but if the inspector really is planning on doing that (usually it's just an empty threat, but that's where attitude comes into play) then the stuff I've been talking about is what he's going to base it on.