but if you must blame anyone aim it at the
Vendor,
Is the vendor necessarily the best party to determine TBO of components? They have pressures on them that may not produce the optimal outcome for the aircraft owner. Shorter TBOs = more sales = more profit. Also they may be worried about litigation so they chose unaffordable safety.
A cost benefit analysis should be conducted when determining the life of a component coupled with service history and the severity or otherwise of the effect failure would have on the continued safe operation of the aircraft. Also the mode of failure of any part should be taken into consideration. ie Does it give plenty of warning or does it fail suddenly and catastrophically.
Vendors sometimes seem to produce very long lists of components with short TBOs.
In the words of Christine Keeler ' Well they would wouldn't they '