Sir Peter, are you aircrew?
I think you are but a moment's reflection would reveal that we would not have a single aircraft flying if we grounded each fleet after a technical failure.
Comet, Hastings, Buccanneer, Vulcan, F4 and I am sure many more have all had catastrophic failures. Identifiable failures are cureable - at cost. The cost was what grounded the Valiant not the failure.