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Cessna’s Latitude – boxing clever

September 19, 2016

 

 

 

The new Citation Latitude is a remarkable example of Cessna’s product development. It takes the successful Soveriegn+ and gives it a new fuselage with a proper stand-up cabin. So the people who actually spend the money love it.

 

Building on the best features of the Soveriegn+, the Latitude will be a great biz-jet for Africa. In the lead up to the 2016 AAD Expo, Southern Africa Cessna agents Absolute Aviation brought a Latitude to their Lanseria base. Our tame biz-jet test pilot, Larry Beamish, who normally flies a comparable Challenger 300, overcame a bad dose of flu to give us an objective assessment.

 

THE CABIN’S THE THING

It’s an old truism that it’s not the pilots, but the man who sits in the back who buys biz-jets, so a great cabin experience is what the Latitude is all about.

The Latitude is Cessna’s first ‘super-midsize’ jet, in that it has a stand-up cabin with a flat floor. It accomplished this simply by taking the CE-680 Sovereign+ and giving it a new, taller fuselage. So the Latitude uses the Sovereign+’s wing, engines and cruciform empennage. In so doing it has created a biz-jet that in almost every respect has less performance that the Sovereign+ – but it is part of a bigger game plan. The new fuselage is the foundation for the soon to be flown Citation Longitude, which really will be a new and great performing aircraft, albeit larger and significantly more expensive.

Cessna engineers resisted the temptation to build the new fuselage out of composites and yet the new larger stand-up cabin is just 350 lb heavier than the Sovereign+. What’s doubly impressive is that cabin pressurisation has been increased to 9.7 psi, providing a 6,000-ft cabin altitude at FL450, the aircraft’s maximum cruise altitude.

The Latitude can carry five passengers, with full fuel, with only a 25-lb increase in maximum ramp and takeoff weights. So it preserves the Sovereign+’s power and wing loading, enabling it to provide almost the same exceptional runway and climb performance. The penalty paid for the larger cabin comes in an almost 30 knot slower speed for the same power setting, and this naturally affects the range and fuel economy as well.

In terms of its midsize competition, the Latitude is 40 knots slower than Embraer’s claimed figures for its Legacy 450. But the Latitude’s stellar short-field performance will make it popular in Africa and enable it to use more small general aviation airports, many of which are closer to the business locations being served. It thus provides a real challenge to the still coming, but significantly smaller, Pilatus PC-24.

The Latitude’s passenger cabin has a larger cross section than any previous Citation. There are six seats in the main seating area and typically a two-seat side-facing divan in the forward cabin, plus a side-facing chair in the lavatory that is certified for full-time occupancy and which makes a good seat for the cabin attendant. The demonstrator that we flew in August had the extended galley which used the space needed for one of the two side facing seats opposite the door.

The cabin windows are much larger than the Sovereign and well-positioned for outside visibility when either sitting or standing. LED lights in the ceiling, chair bases, cabinet and sidewall bottoms make the cabin feel larger than it measures.

The six chairs in the main cabin can track backwards and forward, sideways into the aisle, and swivel 180 degrees. The importance of the flat floor is that passengers apparently don’t like having one foot higher than the other if they extend a leg into the dropped aisle that the Sovereign+ and the Latitude’s competitors have – such are the imperatives of biz-jet design.

The facing chairs recline into full lie flat beds. Each seat has a USB power outlet and each pair of facing chairs has a single 117-volt AC outlet. There also are two 117 volt AC outlets in the cockpit. A 220-volt AC system is available for a nominal charge.

Notably, there are no-longer individual in-flight entertainment TV screens as passengers are expected to use iPads and satellite internet.

 

OUTSIDE

The Latitude is clearly not built for speed. Wing sweep is 12.7 degrees for a typical cruise of 400 to 420 KTAS on long missions. Like the Sovereign+, the wing retains the distinctive ‘swooplets’, Cessna’s elegantly curved interpretation of winglets.

Runway performance is excellent, thanks to six large Fowler flaps which cover nearly 70% of the trailing edge. A flap/stabilator interconnect system minimises pitch force changes when the flaps are extended or retracted between 15 and 35 degrees. The aircraft’s low wing loading, combined with its 1:2.6 thrust-to-weight loading, results in impressive takeoff, climb and landing performance.

The large cruciform empennage may not be as imposing as a T-tail, but it’s structurally efficient. Unlike the similarly sized Legacy 450, the Latitude eschews the complexity of fly-by-wire and instead sticks with tried and trusted ‘fly-by-cable’ manual cable operated controls. This makes the aircraft far easier to maintain in remote African outposts.

The new cabin airstair door is electrically closed, but it can be manually closed as well. The tread on each stair has LED lighting. The single handrail is beautifully leather clad.

The new fuselage is said to reduce both cabin and cockpit noise. The large multilayer glass windscreens have hydrophobic coatings that eliminate the need for windscreen wipers and the noisy bleed-air rain removal system used on previous Citations.

Pilots will appreciate the aft baggage compartment’s airstair door which makes it easy to get into the far corners of the deep baggage bay. The bay is certified to latest FAR Part 25 Class C fire protection standards, having both a quick discharge fire bottle shared with the APU and a metered discharge Halon system located in the nose to progressively suppress any flare-ups.

The single-point pressure refuelling receptacle is normally used to refuel the aircraft. Maximum refill capacity using the single-point system is 10,720 lb, so the over-wing refuelling ports must be used to top off the aircraft to its maximum 11,394 lb.

For remote airfield operations an APU is essential. The Latitude’s Honeywell RE100 APU is certified for start up to 20,000 ft and use up to 30,000 ft.

All landing gear legs have dual wheels. The main gear uses a long-travel trailing-link design for smooth landings and taxi. A conventional brake system with anti-skid uses multi-disk carbon heat packs that are rated for more than 1,000 landings. The main wheel tyres have a design life of 300 or more landings.

Nitrogen bottles in the nose compartment provide emergency braking and landing gear extension functions. A separate accumulator provides alternate nosewheel steering power.

Each wing has five multifunction spoiler panels, the centre three on each wing being spoilerons. The outer panels function as spoilers in flight, and as lift dump spoilers on the ground.

The rudder has a bleed-air-powered boost function that reduces pedal force in the event of an engine failure. The amount of boost is inversely proportional to indicated aircraft speed, so only moderate rudder pressure and retrimming are needed when coping with an engine failure on takeoff. The aircraft has the biggest rudder ever fitted to a Citation, so there’s ample yaw control authority at low speeds in spite of the aircraft’s 5,907-lb thrust engines.

Low and high pressure engine bleed air, routed through pre-coolers in the pylons, is used for cabin pressurisation, heating and air-conditioning, plus wing, horizontal stabiliser, and engine anti-ice. Catalytic ozone converters purify cabin air. The Latitude has a larger, higher capacity air-cycle machine than the Sovereign+, providing increased cooling performance. Pressurisation is controlled by the G5000 avionics system, with the goal of maintaining the lowest possible cabin altitude during each phase of flight. A sea-level cabin can be maintained to FL250.

Long-life LEDs are used for the navigation, beacon and strobe lights. Strangely, old fashioned incandescent lamps are used for the landing and taxi lights.

The aircraft may typically be configured for eight or nine passengers, but most operators will probably carry no more than six on routine missions. As the aircraft can carry five passengers with full fuel, each additional standard passenger reduces maximum range by 55 nm.

An interactive ‘how-goes-it’ moving map is standard and an eight-channel XM satellite radio is an option. Another option is Aircell’s Aviator 300 Inmarsat satcom Internet system. The standard package includes an Iridium satcom phone, Iridium-based request/reply weather system and Aircell Axxess air-to-ground data link with Wi-Fi.

The boss will be pleased with the toilet, which is the largest ever fitted to a Citation. The toilet is covered by a seat cushion that doubles as the lid. To keep the crew happy, the toilet is externally serviced. Aft of the toilet, there is a basin with hot and cold running water. A removable fresh water tank supplies the system. On the left side, there is an aft storage closet and, as noted, a full-time occupancy, folding seat. When the seat back is folded down, it provides an additional storage compartment that can be secured with a cargo net.

 

FLYING THE LATITUDE

Larry Beamish writes: The cockpit is dominated by the Garmin G5000, which controls most systems through the four touch-screen units. Hydraulic, fuel, pressurisation, FADEC and APU controls are moved from the forward tilt panel above the crew’s knees to the centre console where both pilots have easy access to them. Systems synoptics have been added to the engine-indicating and crew-alerting system (EICAS), providing interactive graphics for the normal operations and malfunctions. Individual crews can configure the displays according to personal preference and then save the settings for one-touch recall.

On powering up, the capability of the G5000 can give information overload, so my first request to Cessna demo pilot, Tim Gerlach, was to declutter the displays. This is simply done by pulling down the appropriate menu on the touchscreen and adjusting the level of information displayed.

As in the Sovereign+, instrument panel dimmer rheostats, passenger safety and most exterior light annunciator button switches are located on the overhead panel. The G5000 autopilot control panel layout in the glareshield should be straightforward for any pilot with G1000 experience.

Learning to navigate around the touch-screen pages is a quick and painless process because of Garmin’s use of screen icons. I particularly liked the ability to call up comm frequencies by origin and destination airports in the flight plan and pop them into the radio control pages. Need to look at an airport diagram on the MFD? Just keep zooming in to a lower range scale and it automatically comes into view.

Pre-start checks are quick and easy. Most are automated. You start the APU and switch on the air-conditioning – even on a winter’s day at Lanseria. Unlike the Sovereign+, the Latitude has no opening cockpit windows, so there’s little air circulation without air-conditioning running.

Even though the Pratt & Whitney engines are equipped with FADEC, starting them is a two-step process. The electric starter is engaged by pressing a button in the centre console behind the throttles. Then at 9% N1 turbine rpm, a guarded button is pushed to signal the FADECs to introduce fuel and ignition.

We had 8,000 lb of fuel and five in the cabin, making us around 3,000 lb below gross weight. For takeoff the auto-throttles are armed; however, the autothrottle servos don’t engage until the throttles are to near maximum setting.

We requested a short field takeoff from ATC and were approved for an intersection takeoff from Runway 07’s Bravo 3 intersection. With our typical medium weight of 28,000 lb and 11,500 lb of thrust, a better than 2.5:1 weight-to-thrust ratio provided brisk acceleration. At rotation, pitch forces appeared light to moderate.

Runway roll was impressively short. By the time we passed the B2 intersection, just 850 metres from B3, the wheels were already in their bays. After pulling the nose up to 20 degrees, speed increased quickly through flap retraction. Retracting the flaps resulted in very little pitch trim change. The aircraft climbed through 1,500 ft by the end of the runway.

Jo’burg Radar cleared us for an unrestricted climb to FL360, so we could do cruise performance checks. We got to FL360 from Lanseria’s 4,500 ft in an impressively brief 14 minutes. At a weight of 26,500 lb and in ISA+10 conditions at FL 360, the aircraft settled into a cruise of 252 KIAS for 450 KTAS on 1,980 lb/hr. The book predicted 446 KTAS on 1,987 lb/hr. In cruise the Citation’s characteristic pillowing of the wing panels was remarked up by those in the cabin, but a substantial birdstrike on the leading edge of the right wing during the test flight didn’t leave a scratch, so it’s sturdily built.

Pilots should be unable to inadvertently stall, or overspeed, because the auto-throttles automatically engage for both low- and high-speed envelope protection. Tim said that low-speed protection will be most valuable when pilots are manoeuvring in VFR traffic or circling to land at the end of instrument approaches. I’m not convinced this class of aircraft warrants the complexity of autothrottles, and found it disconcerting that the throttles were hunting individually through turbulence of final approach.

Back in the circuit at Lanseria, our estimated landing weight was 25,000 lb. Tim calculated Vapp at 108 KIAS at flaps 15 degrees and 101 KIAS for Vref using full 35-degree landing flaps.

The aircraft appeared easy to handle on final. At 30 ft AGL, I pulled the throttles to idle. Touchdown was pleasingly smooth, much to the credit of the long-travel, trailing-link landing gear. With spoilers fully extended, mild braking and moderate use of thrust reversers, we turned off at the B2 intersection and taxied back to the Absolute Aviation hangar on the south side.

 

 

Cessna are smart. They have taken their already successful Sovereign+ and given it an all new, bigger and better fuselage. Sure performance and range suffers a bit, but the boss in the back, who buys the plane and pays the bills, will much prefer the Latitude to the Sovereign+. Its 2,850 nm range may not make it a one-stop aircraft to Europe from South Africa, but it goes far enough and quickly enough to make it the ideal business tool for anyone wanting get to any destination in Africa. A typical fuel burn (as calculated by Conklin and de Decker) of US$2.80 per nm makes it a compelling proposition. A 150 order from NetJets confirms that it has everything the market wants from the super competitive midsize class of biz-jet.

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