Story ID: 564
Citation Longitude Development Picking Up Pace
By: Matt Thurber
Caption: Textron Aviation offered a glimpse into the production and engineering processes supporting its newest Citation, the Longitude.
Word Count: 2557
Textron Aviation’s next Citation model–the Longitude–is newer than might be apparent. While the Longitude might seem as though it is a simple stretch of the Latitude, these are two entirely different jets, and their type certification reflects that.

The Latitude’s type certificate derives from the Sovereign, and these two jets share the same Model 680 designation and engine types, Pratt & Whitney Canada’s PW306. One advantage of this is that pilots don’t need a new type rating when moving from the Sovereign to the Latitude, just differences training.

The Longitude is the Model 700 and will have a new type certificate and new pilot type rating requirement. The Longitude and Latitude cockpits are similar, sharing the same Garmin G5000-based avionics suite, but some Longitude systems and the engines are new, and the Longitude production line is also completely new and being stood up in Plant IV at Textron Aviation’s East Campus on Beech Field, the former Beechcraft facility that became part of the Textron family in May 2014.

The first Longitude test articles are now under construction in Plant III, and as the assembly tooling and processes are finalized, the tooling will move over to Plant IV, where space has already been assigned for Longitude production. “This will be the first example of production launched on the east side,” said Ron Draper, senior vice president, integrated supply chain at a media briefing in early May. “We’re bringing jets back to the east side.”

Production Lines

The Latitude is built at Textron Aviation’s Citation assembly lines at the company’s West Campus next to Wichita’s Eisenhower National Airport. One of the new techniques that Textron Aviation has developed on the Latitude line is vertical assembly fixtures for large fuselage components. These fixtures help improve efficiency by allowing technicians to work standing up instead of hunched underneath or kneeling next to a horizontally placed component.

For the Longitude production line, Textron Aviation is adding even more vertical assembly fixtures to manufacture more of the major structures, including wings and fuselage tailcones and other elements. The fixtures are mounted on moveable platforms that ride up and down to put the worker at the right place, improving assembly ergonomics and reducing health problems caused by awkward positioning.

Plant III was most recently used as a warehouse, and previously was the initial development facility for Beechcraft Premier jets. Engineering, manufacturing and tooling development team members are located in Plant III for close proximity to the activities that they oversee. Every morning, team members meet to discuss the day’s activities and any problems that need to be addressed.

“When this tooling is done,” said Draper, “we’ll then switch to rate tooling [for the Plant IV production line]. Much of the refined prototype tooling will be moved to Plant IV for production. Textron Aviation designs and builds its own tooling and fixtures. “That for us is a competitive advantage,” he added. “We start building [these materials] while we’re still in the design phase. The tooling is part of how we build airplanes faster.”

While Textron Aviation does build wings in vertical fixtures for the Sovereign+ and X+, the Longitude’s wing structure has been refined for more efficient production. Most drill-out will be done robotically. And some of the structural components are built at the West Campus using robotic riveting machines.

Team Talk Means Change

A change that resulted from discussions by assembly technicians and mechanics with the design-for-manufacturing team was to enlarge access panels in the bottom wing skin, to make it easier to gain access for assembly and maintenance. When the upper skin is riveted in place, technicians need to be able to reach inside the wing through the access panels, and the larger holes make this easier, especially for the “maximum-size worker.” To prove this change, a test panel was built to see how people fit through the newly sized holes.

“The best solution was getting all of our people in the room to talk,” said Bill Rhinesmith, senior project engineer, Longitude program. The result has been fewer hours spent in manufacturing and assembly, lower component weight and improved efficiency. These lessons learned will be incorporated into other Textron Aviation programs. Another factor that helps improve efficiency is the addition of graphical work instructions to the assembly process. These provide explicit instructions and photographs and diagrams to show assembly technicians exactly how to do each task, and they were first incorporated on the Latitude assembly line. “The idea is to keep the guy or gal working [efficiently],” he said. The instructions also facilitate cross-training so technicians can more effectively learn different tasks.

The Longitude’s wing is new, but it adapts some features from the Hawker 4000 wing, including the loft profile and basic configuration.

Five Longitudes

Five Longitude airframes were under construction in Plant III during my visit in late April. The first airframe built was the one that Textron Aviation unveiled at last year’s NBAA Convention, with a full interior installed. This was TA1 (test article 1), the initial concept airframe used for some ground testing, and it was built on the West Campus.

TA3 (there is no TA2) is the first Longitude on the Plant III line and will be used for extensive structural testing over at the West Campus, then the first prototype (Proto) will fly sometime this summer, followed by P1 through P4, for a total of five flight-test airplanes. Flight testing will be done at Beech Field. “We want the airplane flying out of where the mechanics are located,” said Rhinesmith.

Proto will be equipped with escape hatches, multiple strain gauges and flight test instrumentation and wiring. “We take a lot of readings to make sure it’s behaving the same way we expect it to be,” said Rhinesmith. The first two Honeywell HTF7700L engines had been delivered and were awaiting installation on Proto.

Meanwhile, work is underway to prepare Plant IV for Longitude production. The King Air assembly line was moved to the west bay of Plant IV so that the Longitude line could be placed in the center of the building, which has higher ceilings that can accommodate the tall vertical wing assembly tooling. Some foundation strengthening also had to be done to allow for heavier tooling. The doors at the end of Plant IV also needed to be enlarged by about two feet (in height) to allow the assembled Longitudes to exit the facility. From there, the new Longitudes will move to the paint shop, be test flown and then fly to the West Campus for interior installation and delivery. 

Human Factors Lab

In a nondescript building well apart from Textron Aviation’s more visible West Campus facilities near Eisenhower International Airport in Wichita, a team of human factors engineers and test pilots is busy wringing out various iterations of the Citation Longitude cockpit and flight control systems. The work is done in both Flight Deck Simulator 1, a fixed-base simulator that replicates the Longitude cockpit in the TA-62 lab, and in the TA-59 autopilot iron bird, which uses actual systems hardware to test flight controls, autopilot and other systems.

AIN was given a rare opportunity to visit Building L-22, where the iron birds are housed, and also to fly the Longitude simulator. Iron birds for the Latitude, Sovereign+ and X+ are also located in L-22, along with highly accelerated life testing, environmental, vibration and HIRF/EMI test chambers.

“Our job is to make sure that the human interface with the aircraft makes sense,” explained Matt Archer, manager, human factors. Bringing pilots into the process makes more sense when done early in the development program, instead of trying to fix problems after most architectural and design decisions have been made. Textron Aviation test pilots, delivery and demo pilots and non-company pilots cycle through the simulator, and normally they are familiar with flying Citations and with the Longitude’s G5000 avionics. Pilots usually spend a day in the lab, reviewing procedures and new features in the morning, then in the afternoon flying a line-oriented flight-type scenario, then provide feedback to the human factors engineers.

While feedback is important, the simulator is also equipped with seven cameras that monitor the pilots. One wide-angle camera can see the whole cockpit, while other cameras look at both pilots, including what each pilots’ hands are doing with the controls and the G5000 touchscreen controllers.

The cameras all feed into human factors engineer Leslie Roper’s observer station, where she looks for facial features, hesitations and other indications of what the pilots are experiencing while manipulating the simulator’s controls. This includes checking to see if a pilot is overwhelmed and thus losing situational awareness. Even though the Longitude cockpit is similar to the Latitude’s, this work remains important for each airplane, she explained, “to make sure we’re building on what we’re doing and making it that much better and safer.”

With her observer’s perspective, Roper can see pilots do things that even another human factors team member in the copilot’s seat might not see, such as a pilot reaching up to the guidance panel, then hesitating and trying to decide which knob to turn or button to push. “We’ve noticed that already,” she said. “We’re trying to manage errors as much as possible.” She is also not looking at what just one pilot does but for trends among the group who flies the simulator. “If we notice five pilots [making an incorrect move], we know something is wrong.”

The human factors team also looks at how changes affect pilot actions, because the Longitude is a new airplane. “We’re going to take everything into account,” said Archer, “so that if there is a change, it doesn’t affect something else.”

Ed Wenninger is the flight test manager and chief pilot for Textron Aviation engineering flight test, and he manages the flight test process. “We’re all working together on checklist and procedure development,” he said. “We make sure the information that we give to the crew is not overwhelming.” The idea is to help the crew solve problems without giving them unnecessary information. There is also a rule change in Part 25 that affects the certification basis of the Longitude, having to do with error management and related human factors aspects. This is part of EASA rules that have been harmonized with the FAA.

In a practical sense, what all this work means for Longitude pilots is that the team of human factors engineers and 30 or so pilots will have evaluated the Longitude cockpit in all phases of flight to make it as safe and ergonomically efficient as possible. This might include crafting crew alerting system (CAS) messages so that they make sense in the circumstances in which they are needed, robust checklist procedures and also that a pilot moving from another Garmin-equipped Citation finds a familiar home in the Longitude. “Here we can vet the procedures under much more controlled scenarios than in the airplane,” Wenninger said.

Pilots don’t want to see a lot of differences, Archer explained, and there shouldn’t be radical changes. Any changes should be consistent from cockpit to cockpit and meet pilots’ expectations.

Two-phase Process

The human factors process takes place in two phases. The first is to verify the systems architecture, including CAS messages, ergonomics, panel placement, switchology, etc. In the second phase, the focus is on software and checklists. The Longitude simulator was in the middle of phase one when I visited the L-22 facility.

Essentially what the simulator does is inform the final product. “We’ll get feedback that we can replay and see what went on in the cockpit,” said Pat Winter, senior engineer specialist, aircraft systems engineering. The results may dictate a software change, clearing up confusing switch nomenclature or other changes.

When I saw the simulator, it wasn’t yet fully set up for final testing, with some interior trim, systems and avionics details remaining to be installed so it is representative of the production Longitude. Control forces are replicated using linear inductors, which use massive magnets to fairly accurately simulate the feel of the airplane. It isn’t quite necessary to duplicate exactly how the airplane flies, although the lab does work with sister company TRU Simulation & Training on some of the systems simulations. The G5000 avionics are the real thing and fully flightworthy, according to Wenninger. Ultimately much of the flying is done on autopilot, so the test subjects can focus on the procedures that need to be observed by Roper and the human factors experts.

With Wenninger in the right seat, I flew an extended pattern out of simulated Eisenhower International, taking off and climbing to 3,000 feet, then flying a long downwind before shooting an ILS approach. The autopilot and autothrottles weren’t yet programmed, so it was all hand flying and raw data. The simulated Longitude handles much like the real Latitude and Sovereign, and that is somewhat heavy on the controls but well harmonized and with pleasing handling at low speeds. The linear inductors did an amazing job of replicating a real airplane. The avionics and the visual display made it seem fairly realistic, and I didn’t even notice the cameras locked onto my every movement in the cockpit as we traversed the simulated Kansas skies.

Some of the differences between the Latitude and Longitude are apparent in the simulator. The GTC 570 touchscreen controllers are in the same place as the Latitude, two in the center and one each on the outboard walls for each pilot. The Longitude electrical system is a little different, so there are some new switches, and the jet’s center pedestal is slightly wider but shorter. The G5000 will be able to pull in Sirius XM Weather to calculate takeoff and landing performance data. A consistency monitor checks to see if the flaps setting matches the input data and won’t allow takeoff if the flaps aren’t set correctly. Another new feature of the updated G5000 software is an easier method to switch the big Garmin displays into 60/40 mode by touching one button on the GTC.

The human factors team will continue using the TA-62 lab and the simulator for several iterations of the Longitude software, according to Winter. “We’ll keep it as long as it’s needed.” The original simulator used for development of the Sovereign is still flying; it was used subsequently for the G5000-equipped Sovereign+, then for the G5000-equipped X+, then the Latitude.

This entire complicated process–and there is a lot more to it–carefully tucked away in Building L-22 somewhere in Wichita, is a “challenge of simultaneous maturity,” explained Archer. “A lot is still in development.” Bringing everything together–systems, software and procedures–is, he said, “the art of doing this.”