The AAIB and the helicopter's manufacturer are of the opinion that the electrical energy imparted
by the lightning strike in 1999 exploited the anomaly that was built into the blade at manufacture
and damaged the spar.
The blade was faulty at manufacture and as such may not have been lightning protected.
It is not clear whether they blame the lightning strike or the fault at manufacture which was exploited by the lightning strike.
I stress that on average every airline flying in the USA experiences more than an average of one strike per year.
Pace