Longitude is Clean Sheet Plane- new additions
Part 25 Certification Rules upgraded since last Citation
Cessna added Test Planes to meet Expectations
The Textron Citation Longitude © fills an important strategic position within the company’s range of aircraft offerings. The super mid-size business jet is expected to provide existing Cessna Citation customers with a plane which provides growth in size, speed, range, power, avionics and amenities PLUS excellent operating costs over their existing jet. Thus, at the announcement of this new bird in 2015, it was projected to be ready for delivery in two years.
It is now six months past the calendar goal and last Fall Textron Inc. CEO Scott Donnelly targeted 2018 as the new date. Clearly there is a story behind this slippage and while the answer may not be definitive, there is a very reasonable hypothesis.
Brad Thress, senior vice president of Engineering, said
- That the company taking a “no compromise approach” to certification
- That the company is “[t]his is the most robust certification process we’ve ever been required to conduct for a Citation, which means we will deliver an exceptionally verified, clean-sheet aircraft…”
- He is also quoted as saying “”We’ve had to step up to like, 10 years of rules changes.”
FAA spokesperson Elizabeth Isham Cory explained that since the Cessna Citation Sovereign’s type certification as a wholly new design, “the FAA has updated many transport airplane standards . . . based largely on in-service incidents and accidents or potential precursors to accidents…Meeting the latest standards ensures that new airplanes contribute to the continued safety of the U.S. and worldwide fleet of airplanes…Those safety requirements may add additional testing, but that is typical of any new type certification project.
This is a distinction with great substance. To illustrate what a “wholly new design” means in Part 25 speak, the Douglas Aircraft Company sought the original FAA certification of its DC-9 in 1965 and added models numbered -10, -20,-30,-40,-50 and then new designations MD-80, MD-90 and finally B-717 forty-one years later. The incremental variations supported relatively expedited reviews PLUS the regulations over that period remained relatively static.
Textron’s Longitude admittedly was a clean-sheet design with integration of the latest technology throughout the aircraft; so much of the old certification data was hard to extrapolate to the new plane. Based upon the FAA’s newest certification requirements, the number of the ground and flight test conditions to be met by the Longitude program was nearly double the amount completed on past certification programs. Five Longitudes and nearly 50 ground test articles to expedite testing, whereas previous certification programs featured three aircraft and fewer than 30 ground assets. This innovative approach enabled the program to move swiftly through the development and certification process.
Some of the elements of the Type Certification proof included:
- Runway performance was completed in Roswell, New Mexico, as well as a relatively new flammable fluid testing requirement that entailed 150 hours of flight.
- In lieu of winglets, the Longitude uses “swooplets”,which are more cost efficient but also required certification emphasis.
- Hot and cold weather testing was completed using the all-weather chamber at Eglin Air Force Base in Valparaiso, Florida.
- Honeywell HTF770L turbofans were separately certificated.
Part of the expectations for swifter certification may have derived from the FAA’s promulgation of a performance-based Part 23 which also looks to ASTM for technical supplementation. Even that new regime has taken longer to implement .
The elusive aspect of the certification may be found in the Textron expectations that a clean sheet certification with many technical enhancements could be completed in 24 months. The company’s addition of flight test aircraft and ground test objects were helpful, but they should have recognized the long list of upgraded Part 25 airworthiness requirements.
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