A shining Sovereign

You couldn’t get a better day for flying. There isn’t a cloud in the sky and the visibility is unlimited, courtesy of a westerly breeze. The scene is made complete by the shining Citation Sovereign sitting on the ramp at Sydney, mid-way through its Australian tour with Aeromil Pacific.

Often first impressions can be deceiving, but in the case of aircraft, they can also provide an informed introduction. How an aircraft sits on the tarmac, its intake clearance, undercarriage design and sweep of the wing can all provide an immediate inkling of what the aircraft is about. In the case of the Sovereign, these first impressions give an immediate guide to where the aircraft sits in the extensive Citation family.

At first glance, parallels can be drawn to the Citation XLS+ as the two jets share the taller fuselage offering a stand-up cabin and the nose section of the larger Citations. However, looking closer, the Sovereign is a distinctly different business jet. It is twice as heavy as the XLS+, with twice the cabin interior length and yet the Sovereign can operate out of the same runway length as its smaller counterpart. There is a slight sweep to the wing that is not as dramatic as the Citation X, but facilitates exceptional short-field performance Unlike the XLS+, there are no strakes on the aft fuselage, or dihedral on the stabiliser of this Citation, giving it a somewhat less complicated look.

Certified in 2004, the Citation Sovereign never sought to be the fastest jet in the range. What its design did offer was tremendous short-field performance and impressive payload uplift while still retaining a range of nearly 3,000nm.

After enough loitering at a distance, it was time to take a closer look.

Up Close and Personal

On closer examination, the Sovereign retains many of the features found on both its smaller and larger siblings. On many of its types, Cessna displays the traits of simplicity and a belief that there’s no point re-inventing the wheel if it’s working. It’s a philosophy that is at home on the Sovereign as I inspect its external traits.

Overall it shares the fuselage and nose section of the Citation X, but is actually a little longer at 19.35m. The sleeker, stronger looking nose section and the faired lower fuselage adjacent to the wing root are defining features. These two traits immediately identify the larger Citations from their smaller partners and give them a serious jet-look. However, beneath the style lies function. The sleeker nose houses the aircraft’s avionics, nosewheel steering accumulator, one of two baggage fire suppression bottles and computing capacity. The cockpit windows are electrically heated, without windshield wipers due to a rain repellent coating. Both side windows can be opened allowing last minute ‘administrative access’ once the door has closed. As with the other larger Citations, the faired fuselage provides a straightforward path for systems, cables and hoses to run along the aircraft without interfering with the pressure cell that constitutes the cabin. Furthermore, this area facilitates a shallow drop in the centre wing section that permits attachment of the wings to the fuselage without interruption of the cabin’s cross-section. Common sense is wonderful when it is found in aircraft design.

The tricycle undercarriage employs a chined tyre for water and slush deflection on the nose gear and a trailing arm main landing gear. The four main gear wheels possess multi-disc carbon brakes that are hydraulically powered and actuated by the top of the rudder pedals. The critical ‘V speed’ for all aspects of the undercarriage operation is 210 knots. Electrically controlled, but hydraulically actuated, the undercarriage is depressurised in the up position and held in place by mechanical uplocks. In the event of an emergency, the gear is extended by means of free-fall and pneumatic pressure.

“Common sense is wonderful when it is found in aircraft design.”

The wing is moderately swept at 16 degrees at the leading edges, which are free of aerodynamic devices and de-icing boots as anti-icing is provided by bleed air. These features combine to give the wing a very clean look. Spanning 19m, the wings possess a three-spar design and house the integral fuel tanks capable of carrying up to 5,000kg of fuel. The Sovereign can be pressure refuelled through a single point forward of the win

g, although traditional over-wing fuel caps are available should particular port of call require old-style hose refuelling.

Electrically driven aluminium Fowler flaps are arranged in three sections on each trailing edge and extend up to 35 degrees while the upper surfaces host hydraulically driven spoilers, five per wing, which are utilised for lift, drag, and roll control. This wing is core to the Sovereign’s all-round performance. It is able to maintain a maximum cruise speed of just under 460 knots and yet it can still operate out of 1,100m airfields at maximum weight and land into even shorter ones.

The rear fuselage is typically simple. On the starboard side is an inspection port that allows crews and engineers to easily stand up inside the rear fuselage for inspection and maintenance purposes. The rear-mounted hi-bypass Pratt and Whitney PW306C engines produce over 5,700lb of thrust each and feature FADEC to optimise both the efficiency and ease of engine operation.

The tail section sits 6.2m tall and is pleasing in its simplicity. The fin is reasonably swept and the horizontal stabilizer sits slightly lower than mid-section without dihedral and can be trimmed by an electrically driven actuator. Like the ailerons, the rudder and elevator are actuated by a pushrod and cable system. This simple system keeps maintenance at a minimum and undoubtedly contributes to the aircraft’s dispatch reliability. Even though this aircraft operates at three-quarters of the speed of sound, it still possesses Cessna’s simple, functional design philosophy.

For pitch and yaw control, the empennage incorporates the appropriate control surfaces and systems, including mach trim, rudder bias, and a single yaw damper.

Also housed in the tail section is the auxiliary power unit (APU), which is certified to start up to 20,000ft and continuous operations up to 30,000ft. In business aviation, full ground services are not always available. The APU provides a level of autonomy in cabin air conditioning, electrical power and engine starting when away from base. On the left hand side of the rear fuselage is access to a spacious 100 cubic foot baggage compartment capable of holding a substantial 454 kg of baggage. This section is also equipped with a Halon fire suppression system, reminiscent of equipment found in airline transport category aeroplanes.

From the outside, the Sovereign impresses as a stylish business jet by virtue of its clean, swept, simple form. This simplicity extends to its very core and systems in a manner that is typical of the Citation family. Now it is time to see if the simplicity impresses in the air.

From the Ground Up

Boarding the Sovereign is through a substantial ‘air stair’ that is both light to operate and possesses a passive seal for pressurisation and an acoustic seal for reduced noise levels. Like the top of the range Citation X, the Sovereign offers a comfortable stand up cabin and can accommodate up to 12 passengers, although more realistically it is configured for eight or nine. Once inside, the combination of the ability to stand up and fifteen windows presents a spacious feel.

As always, the interior of this Citation is luxuriously appointed. On the right there is a refreshment centre with two hot beverage tanks, a large ice drawer and numerous areas for storage and catering. A coat closet is just forward of the door on entry and can accommodates navigation charts, flight manuals, coats, brief cases and fire extinguishers. To the rear is another closet, coat rack and externally serviced lavatory. It’s all here. In a functional sense, the cabin is certified to a maximum altitude of 47,000ft and can maintain a sea level cabin up to 25,000ft.

From a pilot’s perspective, the cockpit is equally impressive with a full-glass Honeywell Primus Epic system and FADEC-controlled engines. With every Citation variant I have flown, I have adjusted my seat by feel and then looked for the visual indicators on the central windscreen pillar that are designed for that purpose. And on every Citation variant I have flown, what feels right, is right.

The visibility is tremendous with a relatively high perspective looking down the nose of the aircraft. The flight display is dominated by LCD screens. The entire layout is very clean, from the centre pedestal and thrust lever quadrant, past the two CDUs, central standby instruments and onto the expansive instrument panel and upper mode control panel.

Everything about the layout is in keeping with the clean, efficient philosophy of this aeroplane and carries through to a start procedure that is as simple as they come. Following adequate rotation and airflow through the engine, fuel is introduced by lifting the thrust levers out of ‘Cut Off’ and up to the idle detent. From there, the pilot’s job is to monitor the engine as FADEC goes about its work. After the first engine starts, the status of the electrical system is checked before repeating the process and starting the second engine. I scan the displays, from flight instruments to engine and system indications and the layout is impressive. With the engines started and the avionics online, it is time to get underway.

“Everything about the layout is in keeping with the clean, efficient philosophy of this aeroplane.”

I am sharing the cockpit with Cessna’s Senior Demonstration Pilot Mike Walton who busily goes about entering the airways clearance into the flight management system and confirming our performance data for today’s flight.
Today our takeoff weight is 25,000lb, well below the maximum of 30,300lb. Our critical speeds are V1-102kt, Vr-103kt and V2-111kt, with an initial climb speed of 180 knots. We discuss our contingencies in the case of an emergency and review the taxi route and airways clearance on the large LCD screens. On departure from Sydney we are planned to overfly Katoomba enroute to Cowra before heading back to Sydney from the south-west.

Releasing the park brake, the Sovereign moves off on the level surface outside Execujet without the need for additional power. The residual thrust from the two Pratt and Whitney’s is enough for a comfortable taxi speed, balanced by a touch of toe-brake as needed. To my left is a small knurled wheel that acts as a tiller for nosewheel steering. Initially I am a bit ‘grabby’ as the tiller is very responsive, but before long I am taxiing the Sovereign with ease.

As we taxi all the way to the full length of runway 34 Left, we perform a rudder bias check, test the speed-brake and spoilers and verify the emergency stow function of the thrust reversers. The last check almost seems a little redundant as the reversers are of an over-centre design making it physically impossible for them to inadvertently deploy one would suspect.

With the checks complete and take-off flaps set, we await our turn at the runway threshold. I use the opportunity to re-state the emergency contingencies and review the normal take-off procedure. The latter involves advancing the thrust levers to the third ‘take-off’ detent and maintaining directional control with rudder. When we are lined up and cleared for take-off, that is exactly what I do….and wow!

With passengers on board I would probably ease the thrust levers to that third detent as moving them straight up gives you a truck-full of thrust in the seat of your pants. Very impressive as a pilot, but probably not so for the VIPs in the cabin. Rotating at 111 knots, the fun continues, pitching up to around 18 degrees initially and tucking the gear away. This aircraft can really perform and it is easy to see how it achieves its remarkable short field figures.

Prior to departure, Mike warned me that a good deal of forward stick force and trim would be required on the initial climb and he was right. The Sovereign was like a stallion wanting to keep raising its head and I was required to push and trim quickly to oppose the relatively strong control forces. I suspect that when familiar with this aeroplane, that this tendency would be readily anticipated and countered, virtually becoming second nature. It was purely a by-product of the Sovereign’s impressive acceleration and performance. This aeroplane really wanted to fly and that was fine by me.

We cleaned up and turned left for Katoomba, accelerating initially to 250kt below 10,000ft before accelerating further. I continued to hand fly the aircraft to beyond 30,000ft to develop a feel for the aeroplane. By virtue of its push-rods and cables, one could describe the controls as heavier than some other business jets I have flown, however they are not heavy. And once trimmed, they offer a degree resistance to any over-controlling as was demonstrated when we transited a significant wind change with a few bumps, but no tendency to chase the aeroplane in roll or pitch.

Finally I give in to automation in order to write some notes and allow Mike to point out various features. As we level off at FL400 it has only taken us 15 minutes and we haven’t flown anywhere near a maximum performance climb. In the cruise I set 97 per cent N1 and the Sovereign’s speed settles at Mach 0.785 and offers up a True Airspeed of 435kt in an ISA -10 degrees atmosphere. To achieve this we are burning around 900lb/hr of fuel. The cabin altitude is 5,000ft and the noise levels are very quiet. Despite having an intercom, we are able to easily converse without using them.

As we cruise along in comfort Mike points out a very pilot-friendly feature. It is an alerting system should a pilot commence cross-feeding fuel and become distracted at any point and forget the fuel system configuration. Once the fuel imbalance reaches only 60lb in the opposite direction, an amber cautionary message is activated on the flight panel. This is well below the 400lb imbalance that is quoted as a maximum.

As always I am having too much fun and time flies by as quickly as the Sovereign. We commence our left turn back to Sydney as Cowra slips beneath us and set course for the “Rivet” standard arrival. It’s a quiet time of day, so air traffic control gives us some direct tracking, bringing the top of descent even closer. With the arrival programmed through the CDUs, a vertical navigation (VNAV) profile is generated, so at the calculated top of descent I retard the thrust levers commence a 0.78Mach/280 knot descent. This is achieved with around 80 per cent N1 and provides a descent rate in the vicinity of 2,300fpm.

The weather in Sydney is still as beautiful as when we left it, although there is now a stronger westerly breeze providing a cross-wind on Runway 34 Left. Sweeping around the descending left hand circuit to the runway, the visibility is unlimited and the aircraft is a joy to handle close in. Below 250 knots the first stage of flap can be extended and the pitch change is minimal. Intercepting the ILS, the Sovereign sits steadily on the glide-slope with minimal control inputs required. Below 20kt, more than seven degrees of flap can be selected and I begin to configure the aircraft fully as it is apparent that ATC will be looking to slot one of the long line of departures in ahead of my arrival. Landing gear down and the final stage of flap does offer a more notable pitch change which is easily countered.

The Vref is 106 knots with 35 degrees of flap and Mike suggests we fly the approach at 120 knots. Now fully configured, the localiser and glide-slope are easily maintained despite the breeze and a few bumps. Only a squeeze of the throttles is needed to adjust a knot of airspeed here or there, but fundamentally the Sovereign just sits in the slot and makes you look good.

Over the threshold I begin to flare and bring in just enough rudder to align the Sovereign with the runway and enough aileron to prevent drifting downwind of the centre-line. The control inputs correspond nicely with the picture I see outside the window and I am set for a reasonable landing. And it was reasonable, although I was a little slow on the speedbrake and the ‘into wind’ wheel skipped on first contact before settling on the runway with the second. I grizzle at myself, although Mike assures me that it’s almost routine for the first Sovereign landing. This aeroplane just simply wants to fly.

As we taxied back to the parking area, ably assisted by the Jeppesen display, my overwhelming impression of this aeroplane was its get up and go and its substantial feel. This aeroplane looks, feels and flies like the serious business jet it is.

More to Come

No sooner have I parked the brakes than the discussion turns to the new Citation Sovereign. Factory-standard winglets, canted engine nozzles on the Pratt and Whitneys for improved wet field performance, a new cabin interior and a Garmin G5000 avionics suite with Synthetic Vision Technology. There is even better climb performance, greater range and more payload with a full fuel load.

However for me, this Sovereign has done enough to impress here and now. It is a tremendous performer with wonderful mission flexibility. Its 3,000nm range is almost at odds with its need for only 1,100m of runway for takeoff at maximum weight and allows it to fly anywhere in Australia nonstop. Additionally, Aeromil Pacific is utilising factory-supplied data to develop an unimproved runway kit for the Sovereign which consists of a nose wheel deflector and flap protection along with underbelly protection for antenna and lights. Combined with its short-field figures, this kit should open up numerous regional dirt airstrips to the Sovereign.
This aircraft has retained Cessna’s philosophy of simplicity, but not at the cost of style. This is a very capable business jet.

“It is a tremendous performer with wonderful mission flexibility.”

As for the new model? Well I won’t say too much just yet. Hopefully time will tell and will I have the opportunity to take the swept wing variant aloft too. Regardless of the future, the Citation Model 680 as flown is a shining Sovereign in its own right.

(The author would like to thank Nick Jones and Aeromil Pacific for their efforts in making this air test possible)