Complex sentence: The purchase of the F-111 was a major political issue in the late 1960s and early 1970s due to price escalation and late delivery, although it was expected to have a service life of well over 50 years.
Split into simpler sentences: The purchase of the F111 was a major political issue in the late 1960s and early 1970s due to price escalation and late delivery. On the other hand they are expected to have a service life of well over 50 years.