Think we can safely say this is an industry problem, look at the recent report of a 747-300 written off in Bangladesh after an incorrectly assembled fuel coupling caused a fuel leak and fire. Just in my 30 odd years fixing aeroplanes the training has been drastically reduced, trades have disappeared . The newer generation aircraft are generally easier to work on. Legacy aircraft both civil and military require greater skills to maintain which takes time to learn, and then you need to retain those skills , how many people want to remain spannering an old fleet with minimal job prospects? No easy answers to any of it except investment in people and money , but we are in a culture of cutting costs and standards. Also look at the equivalent aircraft in this role , the P3 , severe corrosion problems , with a large chunk of US fleet grounded or out of service soon , soon to be replaced by a 1966 designed jet . So no different to our issues really. Think we need a rethink on our military investment , if we are going to do the job properly we have to pay for it . Looking at the job done by the Nimrods in well over 30 years has been very good value for money, so a few more million a year to keep what is not a large fleet going safely would be a good investment.