I know absolutely nothing about airworthiness regulations, but if the item in question is ubiquitous with millions of hours of service, then surely that can be leveraged?
My thought train goes like this: A bicycle is a simple, inexpensive device that can be inspected, fitted with operable brakes, reliable bearings and chain, and can be declared safe. The consequences of a failed bicycle are generally minor injury, but with the potential of more serious injury or even death, rarely.
A car is more complex than a bicycle, but can be engineered safely, and the lessons of thousands of designs have been learned over the years to make a safer motor car. If a part fails in service, it is replaced, even if that requires a recall of hundreds of thousands of vehicles. The consequences of a safety failure in a car are likely severe injury or death.
Are not aircraft safety regimes much the same? The consequences of failure are almost certainly death, so it is that much tougher. But with millions of hours of operation of the 707 and derivatives, surely the delta from a bog-standard airframe is the prime area of concern rather than the whole thing?
I appreciate this is a vastly more complicated affair than I simplistically illustrate above, but for the MRA4, with a genesis period of over 10 years and billions of pounds spent on a tiny fleet, it seems that it could have been signed off, but for the want of a bit of reasoned thought and risk analysis. Even the safest aircraft may have an accident due to incorrect fuels/oils being used, or dare I say, crew error. It's always a risk going aviating.
Last edited by Roadster280; 17th May 2013 at 16:01.