Complex sentence: Declining sales of the Apache prompted the redesign dubbed PA-23-250 Aztec, with 250 hp (186 kW) Lycoming IO-540 fuel-injected engines and six-seat capacity, which became available in 1959 and continued in production until 1982.
Split into simpler sentences: Declining sales of the Apache prompted the redesign dubbed PA-23-250 Aztec, with 250 hp (186 kW) Lycoming. The later models of the Aztec where equipped with IO-540 fuel-injected engines and six-seat capacity and continued in production until 1982.