STC for Clifford Development’s Citation 550 mod

The FAA has issued a final STC certificate to Clifford Development, which covers modification of the 550 and S550 Cessna Citation Series aircraft using Williams International FJ44-3A engines.

This is the first STC issued to cover both Cessna Citation aircraft. It was issued with no operational limitations or restrictions.

Certification flight tests document significant speed, range and direct operating cost improvements with the STC, which is available for installation at four Clifford service centers, according to company officials.

“With its 35% reduction in average trip fuel consumption and noise reduction greater than Stage 4 standards, this STC transformation vaults the eight-passenger 550 and S550 into a completely new jet category,” noted Jim Clifford, CEO.

In addition to the engine modification, Clifford Development certified 35 improvements as part of the STC, including: an Ametek digital engine display, heavy duty BFG brakes, and a dual FADEC system certified to July 2007 FAA standards. With this modification, the typical Citation 550s empty weight will be reduced by 250 lbs.

Based on certification flight test data, company officials report that the re-engined aircraft have significant performance improvements: less than 27 minute time-to-climb to FL430 versus the current one hour and 30 plus minute step-climb profile; a 50% increase in NBAA range with four passengers; and a 15% percent increase in max cruise. The Williams FJ44-3A engines are thermodynamically rated at 3,000 lbs. (with a takeoff flat-rated thrust of 2,820 lbs.) versus the original engine’s 2,500 lbs rating.

The 550 engine conversion is priced at $2.295 million for 2009 installations and the S550 conversion is priced at $2.395 million with winglet for 2009 installations. Prices include engines, engine core credit, digital engine instrumentation, Clifford Development aircraft improvement package, installation labor and training.

Clifford Development has appointed Great Lakes Aviation, Kalamazoo, Mich.; Threshold Aviation, Chino Calif.; Central Flying Service, Little Rock, Ark.; and Stevens Aviation, Greenville, S.C., as service centers.

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  1. Brandon Vlasak says

    What ever became of this program? I can’t find any more info available online beyond your article.


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