Clifford Development Launches STC Program to Certify Citation S/II with Williams FJ44-3 Engines

Kalamazoo, Michigan, September 10, 2007 – Clifford Development has initiated a Supplemental Type Certificate (STC) program to re-engine the Cessna Citation S/II (CE-S550) with Williams International FJ44-3 engines. Clifford Development is currently certifying Williams FJ44-3 engines for the Cessna Citation II.

“We are pleased to launch this effort to re-engine the Citation S/II working in collaboration with Williams International. Operators have expressed interest in the Williams FJ44-3 engines and the substantial performance, safety and operating cost improvements these engines promise. Plus, our Citation II certification program has led us to over 30 systems enhancements that can also be incorporated into the Citation S/II STC. We will at the same time be developing a new performance winglet,” noted Jim Clifford, chief executive officer of Clifford Development.

Based on performance computations completed using the NASA-developed General Aviation Synthesis Program (GASP), Clifford expects the re-engined CE-S550 will have significant performance improvements including a 75 percent reduction in time-to-climb (FL430), a 40 percent NBAA range increase (with four passengers), a 34 percent improvement in single engine climb rate and a 28 percent reduction in fuel costs. The FADEC integration reduces takeoff field length 10 percent without thrust reversers.

The STC for the Citation S/II will include the installation of winglets to enhance the airplane’s fuel specifics, operating economy and range.

“For a Citation S/II operator whose airplane is facing second overhauls, 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. A key to these savings is the Williams engine’s 4,000-hour overhaul interval versus the original engine’s 3000 hour interval,” noted Clifford.

Work on the certification airplane will begin in late September. First flight is scheduled for November 2007 and issuance of the STC is anticipated in early 2008.

The 2007 Citation S/II engine conversion is priced at $2,185,000 including engine mount kits, nacelles, engines, winglets, installation and training. The price includes a credit for the original engines. Customer installations will be handled by service centers in North America.

About Clifford Development – Clifford Development was formed in August 2006 by industry veterans to rapidly engineer new engine technologies for the fleet corporate jets. The engineering team has developed over 3000 STCs collectively. The company will fund major certification programs to enhance the safety, value and performance of corporate jets. The company will focus individual teams of highly experienced aerospace engineers on certifications programs using the best available project management technology and certification processes. Contact Mr. Alden Andre at: or visit the web site at for product information.