More than four years after its unveiling at the 2015 NBAA Convention in Las Vegas, Textron Aviation’s Cessna Citation Longitude received its long-awaited type certification on September 21 followed by entry into service on October 2. “The newly certified Citation Longitude brings unrivaled technology to the business travel market, for both the passenger and the pilot, offering our customers the most efficient and productive super-midsize jet now in operation,” said Textron Aviation president and CEO Ron Draper. “We are thrilled to now transition this program into service.”

Recipients of the first Longitudes were not disclosed by Textron Aviation (Booth C9343). Fractional provider NetJets is among the type’s biggest customers, having agreed to purchase up to 175 Longitudes including an option to take first deliveries in the second half of this year. In a September 23 note to investors, Bank of America Merrill Lynch analyst Ron Epstein forecast two Longitude deliveries in the third quarter that could possibly slip into the fourth quarter.

In what Textron Aviation called “the most robust flight, structural, and component qualification testing completed on a Citation to date,” the experimental and demo fleet comprising five flight test vehicles completed nearly 6,000 hours of flight time, as well as 11,000 test points. During the certification process, the 3,500-nm-range Longitude also flew a 31,000-nm world tour. 

Certification of the $26.9 million airplane was originally expected about two years ago. 

Fuel Tank Flammability Delay

But at least one issue, fuel tank flammability, hampered Textron Aviation’s certification timeline for more than a year and a half while the manufacturer sought an exemption.

Textron Aviation’s initial appeal for exemption in February 2018 centered around a difference in interpretation between the FAA and the company on what constitutes a center fuel tank. The Longitude is designed with the fuel tank in a conventional unheated aluminum wing but includes a portion covered by aerodynamic fairings. The company considers the entire fuel tank to be in a conventional unheated aluminum wing (CUAW) that meets flammability requirements. 

But the FAA disagreed, determining that the portion covered by the aerodynamic fairings is not a conventional unheated aluminum wing tank, which means the aircraft doesn’t meet the requirements of FAR 25.981(b), amendment 25-125.

In its earlier exemption request, Textron pointed to the safety records of other jets in its fleet with similar fuel systems such as the Citation Sovereign and M2, as well as the Hawker 4000. A temporary exemption issued in August 2018 accepted an interim modification and called for a long-term solution. 

A second appeal made by Textron Aviation in December 2018 was more narrowly focused on the more extensive requirements that apply to the use of the flammability reduction means (FRM) in fuel tanks. The FAA has determined that the aircraft's dedicated electric recirculation pump is an FRM and therefore the aircraft must meet those requirements.

In its June 26 decision granting the exemption, the FAA said: “the design modification that Textron has incorporated in the Model 700, in order to cool the fuel tanks and reduce fuel heating, improves the overall tank flammability to a level equivalent to a CUAW tank.”

The Longitude was Cessna’s first clean-sheet design since the midsize Citation Sovereign was certified in 2004. 

Longitude also carries the distinction of being the first Cessna to be manufactured in a Beechcraft plant. It is at the former Beechcraft Plant IV—now designated as the Textron Aviation East Campus following Textron Inc.’s acquisition of Hawker Beechcraft in 2014—where the Longitude is assembled alongside King Air turboprops. Its production line previously served as the line for the short-lived Hawker 4000 super-midsize jet.