Complex sentence: Production continued until 1989 at a much slower pace than foreseen in the contract: nine aircraft were delivered, with the 10th and 11th aircraft on the production line being abandoned when they were 85% and 70% complete.
Split into simpler sentences: Production continued until 1989 at a much slower pace than foreseen in the contract. Nine aircraft were delivered, with the 10th and 11th aircraft on the production line being abandoned when they were 85% and 70% complete.