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That investigation report of the incident in Canada with the helicopter is available on the internet. For those that haven't seen it, a small helicopter crashed shortly after takeoff, into a lake. The pilot survived, although his harness broke upon impact. To summarize their findings; the belt was assumed to be 27 years old based upon a date on a label on the lap belt, had no fraying or damage but did have some sun fading on the portion of the belt that was not retracted into the retractor when stowed. The belt was 2 inches in width, with a nominal strength of 1500 pounds and a minimum design failure strength of 2,250 pounds. It failed upon impact at a section where there was discoloration from fading due to UV exposure. Subsequent destruction testing showed the faded portion failing at less than 600 pounds and the unfaded portion failing at under 1500 pounds.
I suppose we can assume from this that all belts will lose strength with age and the more sunlight exposure one receives, the worse it gets. A 27 year old belt seems quite old but, if you look in my garage, I have 3 cars with belts older than that and many more with belts 20 years old, or so. All seem cosmetically fine but some are starting to feel stiff, so you have to wonder what shape they are really in.
For what it's worth,
JR
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