Somewhat on the same topic , my first aviation job after leaving college around 1976 was at Westlands in the Composite Development . We built a tail boom for the Westland Scout from HIgh Modulus unidirectional carbon fibre ( Ciba Geigy product ) . I witnessed the final destructive test , I do not recall if it exceeded design limit but I will never forget the loud crack when it failed and the numerous pieces of carbon fibre that flew all through the hangar. Thankfully the woven fibres now available have much better properties.