Clifford Development Appoints Threshold Aviation as Service Center for Citation II Re-Engining Program

Kalamazoo, MI, July 10, 2007 – Clifford Development announced the appointment of a new service center to support the Company's Citation II re-engining program. The Company is in the midst of a Supplemental Type Certificate (STC) development program to re-engine Cessna Citation II (CE-550) aircraft with 3,000-lb thrust Williams International FJ44-3 engines including integration of the FADEC (full authority digital engine control) system.

Threshold Aviation Group of Chino, California has been appointed as a Clifford Development service center for the Citation II engine program. Service centers will provide complete sales, installation and service support for Citation II owners who purchase the Clifford engine STC. Service centers will receive technical support and complete installation kits from Clifford Development including engines, engine mounts, nacelles, all service documentation and pilot operating handbook document for the modified airplanes. Installation time for new engines is estimated at six weeks.

"We are very pleased to announce the appointment of Threshold Aviation Group as a service center," said Jim Clifford, chief executive officer of Clifford Development. He added, "From the start, we set very specific criteria for our service centers. Threshold Aviation Group exemplifies the key attributes of high technical standards and impeccable customer service."

Based on performance computations completed using the NASA-developed General Aviation Synthesis Program (GASP), Clifford expects the re-engined CE-550 will have significant performance improvements, including a 21 percent long-range cruise speed increase, a 29 percent range increase, a 34 percent improvement in single engine climb rate and a 20 percent improvement in fuel efficiency. The FADEC integration allows for a decreased takeoff field length.

The STC engineering effort is nearing completion. Williams FJ44-3 engines have been installed and run on a certification airplane. First flight of the Cessna Citation II with Williams FJ44-3 engines is anticipated in July 2007. Immediately after local flight evaluations, the certification airplane will move to Mojave Airport to begin 250 hours of test flights to verify performance and to meet the FAA requirements. Issuance of the Supplemental Type Certificate is slated for fourth quarter 2007.

The Citation II engine conversion is priced at $2,150,000 for 2008 installations. This price includes engine mount kits, nacelles, engines, engine instrumentation, installation labor and training. The price includes a credit for the original engines.

About Clifford Development – Clifford Development was formed to rapidly develop STCs for the installation of new engine technologies on the existing fleet of high value corporate jets. The company will fund major re-engining certification programs to enhance the safety, value and performance of corporate jets. The company will focus individual teams of highly experienced aerospace engineers on certification programs using the best available project management technology and certification processes. Detailed performance data on the re-engined Citation II are available at More information about the Williams International FJ44-3 and Williams’ world-class product support is available at

About Threshold Aviation Group – Threshold Aviation Group is a full-service aviation company based in Chino, CA. Founded in 1990 by Mark and Lisa DiLullo, the company operates from a 136,000 square foot modern hanger complex on the Chino Airport (KCNO) in Southern California. Threshold provides maintenance and management services to a wide variety of operators in the private and corporate business jet community, including an in-house fleet of 30 aircraft. Threshold provides maintenance for Light-Jets thru 72-month Gulfstream III inspections, complete interior design and fabrication, with avionics and paint availability. Threshold employs over 40 full-time maintenance personnel operating in two shifts and has the capacity and capability to fulfill the most demanding maintenance requirements.

Most recently, Threshold opened a brand new, full service FBO at Chino Airport. Threshold's FBO was designed to give corporate aviation clients a viable alternative to Southern California's congested airports, which are literally minutes away. Visit Threshold Aviation Group on the Web at: