Clifford Development has expanded certification efforts for its Cessna Citation II re-engining and airframe modification program to include the S/II (CE-S550). Like the company’s Citation II program, the modification will include replacing the S/II’s Pratt & Whitney Canada JT15D turbofans with Williams FJ44-3 turbofans, as well as adding winglets and more than 30 other systems enhancements. Clifford expects the re-engined CE-S550 will have significant performance improvements, including a 75-percent reduction in time to climb to FL 430, a 40-percent NBAA range increase (with four passengers), a 28-percent reduction in fuel costs and shorter takeoff field lengths. “The gains in fuel efficiency and speed, combined with reduced engine maintenance costs, can allow recovery of this investment in three to five years of typical operation,” the company claims. Work on the certification airplane will begin later this month, with first flight scheduled for November. STC approval for the $2.185 million conversion is expected early next year.