could not have any components that were past 50% of their expected life and the same rules were applied to our Wessex in Cyprus when we flew Princess Anne back in the 80's.
Interested to read this - when we flew HRH The Princess Royal on her annual visits to the Northern Lights lighthouses (3-4 days, flying off the NLV Pharos) we just used the standard Bond Air Services Bo105. I'm 95% sure no airframe component life issues were raised beforehand - sourcing suitable parts may well have proved impossible.