Several thousand hours reliance on rotary wing flight (similar on fixed wing) convince me that both forms can offer sufficient challenges to not need adding to. This would appear to be a concept foreign to the wazzock in the Robbie. Apart from the incidents mentioned above, personal knowledge recalls blades plus MRG departing a Whirlwind in Cyprus (undrilled grease nipple), similar at Valley (faulty distance judgement) and blade weight departure at Boscombe on early model Lynx plus sundry other unplanned 'earth returns'. A 'catalogue' which might give pause for thought, - a process which the subject has managed to avoid !