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A Grand Design

A Grand Design

Flying the Cessna Grand Caravan Ex.

 

words: Owen Zupp

Performance can mean many things to many aircraft.

Fast, slow, short-field, heavy-lifter. Often an aircraft’s role can be ascertained merely by looking at it. In the most obvious case, a flying boat, more subtly, a freighter. Yet, even when the design suggests the suitability of an aeroplane to a particular task, there can still be much to be discovered when we pause to look a little closer. Such is the Cessna Grand Caravan EX.

 

A Growing Reputation

The Cessna 208 Caravan family first came into being in 1985, seeking to fill the role of a single-engine utility turboprop across a range of operations.

Federal Express, or FedEx, then ordered a freight version of the aircraft without cabin windows. Known as the Cargomaster the design was further developed to become the Cessna 208B Super Cargomaster by extending the fuselage by 1.2m and fitting a substantial cargo pod on its underside. This larger version was then developed for passenger operations and the Grand Caravan came into being in 1990.

The stretched Caravan seemed to provide just what operators were looking for and came to dominate that niche of the market. To date, around 500 Caravans have been delivered, while well over 2,000 Grand Caravans have found their way onto flightlines around the world, of which 100 are on the Australian register. That number includes special mission aircraft in service with the NSW and Queensland police forces.

The success of the design was further emphasised by the fact that it remains fundamentally unchanged. A Garmin G1000 glass avionics suite and TKS Ice Protection were added in 2007, while the Grand Caravan EX with its more powerful engine was introduced in 2012. For the EX the ever-reliable Pratt & Whitney Canada PT6 engine was upgraded to the PT6A-140, generating 867shp, or 200 more horses than its predecessor. More than 400 Grand Caravan EXs have since been sold.

The formula to this success may seem relatively straightforward. Single pilot operation, simple systems, a high degree of reliability, versatile in its capability and low operating costs. A simple formula that would be a challenge for any manufacturer. But Cessna seems to have got it right.

Behind the Numbers

Whether an aircraft is a private tourer or a commercial workhorse, there are certain facts and figures that are particularly meaningful to the operation. It may be the range of an aircraft with the entire family on board, or it may be whether the available payload is enough to make a freight company profitable. With its vast range of applications, the Grand Caravan EX has to answer questions like those for multiple scenarios, including when the aircraft is equipped as a floatplane.

The EX with an external cargo pod has a maximum takeoff weight (MTOW) of 3,995kg and offers a useful load of more than one-and-a-half tonnes at 1,607kg. With a full usable fuel load of 990kg, the EX has a maximum range of just over 900nm and a payload of 600kg, or seven people, depending upon their weight.

However, this aircraft can, and does, use that available payload in a variety of ways. In a maximum seating configuration of 14 people on board (at 77kg each), the aircraft can still carry 520kg of fuel and offer a range of 360nm on commuter or scenic runs. In doing so, it runs at a miserly 38 cents per seat-mile. Configure the aircraft more spaciously to carry 11 in a commuter configuration and range extends to more than 550nm.

If a special mission is called for such as police surveillance, it has an outstanding endurance of eight hours, with excellent slow flight characteristics which means it can hold station and loiter with efficiency.

The numbers for the task-specific Super Cargomaster are even more impressive as the absence of seats logically lowers the empty weight and avails a greater payload – nearly 1,800kg in fact. Not immediately evident by the numbers is the volumetric efficiency of the cabin. It’s angular, rather than tubular, cross-section provides a better fit for the boxes it is asked to lift. No wonder FedEx loves this aeroplane!

In its own right, the cargo pod carries 494kg in its 3m3 capacity. Its four compartments are accessible by large individual doors, with the central compartment holding the anti-icing fluid if the TKS system is fitted.

Even when loaded to its capacity, the Caravan EX can takeoff from 660m and land in only 570m. While the aircraft is not pressurised, fitted with supplemental oxygen it has a ceiling of 25,000ft, but to be honest that’s not where the Caravan calls home. At 10,000ft, it is free to ply its trade at a very respectable 185kt.

With that maximum range of over 900nm, the Caravan EX has long legs, but its versatility is the most impressive aspect of its performance figures. Fast or slow, long range or loiter, comfort or cargo, the aircraft can fit the bill.

 

Standing Tall

The heat from the ramp outside the Hawker Pacific facility at Bankstown Airport can be felt through the soles of the shoes. The low cloud and rain of the previous day have been replaced by a cloudless sky and a sun that is beating down. While the Caravan EX is approved for flight into known icing conditions (FIKI), the current conditions are more reflective of the environment in which the aircraft would be called to operate in around Australia’s top end.

The most striking first impression is how tall the Grand Caravan sits on its fixed tricycle undercarriage – it dominates the other light aircraft around it. However, sheer size and capacity is not its only strong point as I begin an external walkaround with Textron pilot, Jeremy Schrag. This is a very well thought-out aeroplane.

The Cessna trademark wing struts extend up from the fuselage just in front of the main landing gear. Nearby is the filler port for the anti-icing fluid and single-point refuelling station if it is fitted – a greatly appreciated option for floatplane operations. Sensibly, this all takes place about the aircraft’s centre of gravity and the strut extends up to the wing on both sides at a junction which houses fresh air intakes for the cabin. Some aircraft have these intakes, or ducts, on the aft fuselage where they are still susceptible to harvesting the scent of engine exhaust – not the Caravan. They are well removed and definitely situated in the free airflow.

The wing itself is the first hint that the Caravan EX is “just a big Cessna 182”, as so many people assert. It is a big wing, true, but aside from the streamlined weather radar pod on the leading edge of the right wing and LED navigation, takeoff and landing lights, there’s nothing fancy. Big solid flap hinges, relatively highly cambered aerofoil, dual pitot-static probes and so on. The sprung-steel undercarriage has a broad gait and little more. The aeroplane looks built to work, but the subtle fact is that it still cruises at 185kt. Clydesdales aren’t often racehorses.

The nose gear is also deceptive. At first glance it appears to be the standard nose oleo arrangement, but it is actually a dampening arrangement engineered with a slightly arced drag link and a snubber system. This is good news for outback operators as there is no integral seal that can fail and leave the nose strut compressed. No oil – no worries. Very clever.

There is very little that needs to be said about the venerable Pratt & Whitney PT6. Beneath the cowls is a very well laid out turboprop engine turning out 867shp. Manually activated inertial separator to the rear, ‘sight glass’ oil level gauge, easily accessed hot section for maintenance and an even easier-to-access and remove battery. For the record, in a situation where electrical power is lost, the battery can provide up to 60 minutes of power with some shedding of services.

The exhaust is channeled out via a single exhaust stack beneath the fuselage on the right-hand side. This not only rids the forward field of view of an exhaust stack protuding on each side of the cowling but removes the distortion of visibility that such a configuration can cause and consequently interfere with surveillance duties. That exhaust scent is also dispatched down and away from the passenger cabin.

Head-on the Caravan EX boasts a four-bladed McCauley propeller with a great deal of clearance from the dirt airstrips that it could be called to operate from. Like a number of highly powered single-engine turboprops, the engine is slightly offset to counter the yaw on takeoff that such a powerful engine can generate.

Stepping back and continuing to walk around the Caravan EX, the ‘stretch’ from its predecessor is apparent. Two 60cm sections, fore and aft of the wing root, separates the Grand Caravan from its forbear. Logically, the stretch is either side of the centre of gravity, so one could assume that there was minimal impact upon the balance characteristics of the aircraft when it was extended.

The aft section of the aircraft has a towering, but conventional, tailplane. The entire empennage is solid and practical, with both the rudder and elevators horn-balanced. There is a control lock evident on the port-side for use when parked in gusty conditions, although this automatically disengages when the elevator is deflected upward about one-fourth of its travel. On the underside is the port for the ‘pogo-stick’ to avoid any possible chance of the Caravan EX sitting on its tail during loading.

Entry to the cabin can be achieved through three major means – the passenger airstair on the right side, the huge two-part freight door on the left side and the crew door. Although the Caravan sits tall, the passenger airstair extends low to the ground allowing ease of access. On the opposite side, the cargo door can accept a pallet, but there’s more to it than that. With the single exhaust located underneath and on the other side of the fuselage, the Caravan can load and unload with the engine running, achieving hot turnarounds without the exhaust flowing straight back at the ground crew.

From a pilot’s perspective, the crew door allows boarding via a small self-contained ladder. Once standing at the entry to the cockpit there is a handle to brace with, allowing an excellent view of the wing’s upper surface and one last peace-of-mind check that the fuel caps are in place and secure. This is a very well planned aeroplane.

Taking Flight

Within the cabin, the Caravan EX is a chameleon. Its interior can range from a spartan freighter interior through to the ‘Oasis’ suite of executive luxury. In between lies a range of variations that offer commuter passenger comfort, while a combi option can plug windows and remove seats to quickly ready the aircraft to carry cargo.

Seated in the cockpit, the Caravan EX has a presence. This is partially due to the height the pilot sits above the tarmac and is reinforced by the excellent visibility. The outlook is achieved by the expansive windscreen supported by a large side window with a low sill. Furthermore, the leading edge of the wing sits some distance back and so as to not obscure the view.

Inside, the cockpit is well laid out and functional. Switches are grouped logically, everything is within easy reach and the fuel selectors are big and obvious, located overhead – minimising the piping to the tanks one would suspect. Everything has a substantial feel and it does actually feel like a big 182 – but that’s a good thing as that aircraft has a reputation for reliability and getting the job done.

One distinguishing feature of the latest EX is the Garmin G1000 NXI avionics suite. The Garmin G1000 first appeared in the Caravan in 2007, but last year saw the introduction of the NXI. It has increased processing capability which means that it boots up more quickly after start. Additionally, it has an enhanced HSI with various overlay options, a vertical profile display, numerous charts and an optional ‘surface watch’ function which offers various cues and warnings relating to the runway for takeoff or landing.

Jeremy and I are both keen to get underway and allow the air conditioning to cool us down, so without fuss we start the PT6 with the simplicity that these amazing Pratt & Whitney engines are renowned for. In no time at all, the engine is stable and the NXI avionics come to full life in a fraction of the time normally associated with the G1000.

Taxiing the Caravan is simple, and the rudder pedal forces are well in line with the aircraft’s size. The brakes don’t need to be touched either until approaching the run-up bay as the speed is simply controlled by easing into ‘beta’ range to slow down. Preflight procedures are minimal and straightforward, lending the aircraft favourably to multiple sectors and short turnarounds. Soon we are cleared for takeoff to the west and entry into controlled airspace.

Jeremy had advised me that the performance figures were conservative, and he wasn’t kidding as we became airborne just beyond the numbers and climbed away at an impressive angle.

From the outset, the aircraft handles without vice. It has to be positively flown and trimmed, but when it is sitting in its slot, it is very stable. This makes for a smooth ride for passengers and a stable platform for the special missions roles to which the aircraft can also be adapted.

Level at 6,000ft with the prop RPM at 1,750 we have a true airspeed (TAS) of 184kt, just as advertised. I also note a blue bug on the torque gauge, colloquially known as the ‘cruise bug’. This clever blue indicator appears to show the optimal torque to be set, taking into account the actual ambient conditions in a way that the tables in the performance manual cannot.

Clear of controlled airspace, I fly a series of manoeuvres including steep turns and I am very impressed with the handling of the aircraft, both with and without the yaw damper engaged. Throughout, the aircraft responds in pitch and roll in the right measure for the inputs through the yoke and once an attitude is set, it holds it. In the slow speed regime this is particularly evident, and it is easy to see why the aircraft is well suited to surveillance operations with such good low speed handling and extensive endurance.

Moving through the flap range, in both extension and retraction, there are definite pitch changes, but these can be easily trimmed out. In fact, Jeremy showed me the ideal way to manage the situation with ease by starting the electric trim as soon as the flap is selected and holding it until the flap reaches the selected position. The timing of flap and trim is virtually identical and makes for very smooth transitions.

All too soon we begin a descent to return to the circuit and although the Caravan EX looks like a workhorse, as we said, looks can deceive. I can personally attest to the fact that the aeroplane can quite quickly approach its limiting airspeed when it is pointing downhill.

The aircraft’s excellent handling characteristics hold true in the circuit. On downwind behind much slower aircraft, the Caravan EX can be reeled right in to conform to the traffic and with a little extra width, save air traffic controllers a headache. Aiming for around 80kt over the threshold, the speeds are comparative to a much smaller aeroplane and the propeller disc serves as a tremendous aid in speed control.

Raising the nose cowling to the horizon sets the attitude for the flare and the wide-sprung undercarriage offers a great degree of forgiveness. Even with only Beta selected, the landing roll is short, so it is easy to see how the landing distance quoted in the manual can be achieved, if not beaten, when reverse is employed.

Taxiing back to the parking bay, Jeremy reminds me of a light shudder the undercarriage can sometimes produce under braking due to the geometry of the landing gear. However, despite our best efforts, we are unable to replicate the effect, so I suspect its occurrence may be the result of a particular taxiing technique.

With the brakes parked, I shut the Caravan EX down and its propeller slowly spools down to a halt. I open the crew door and extend the ladder. This has been a most enjoyable flight.

Exquisite Simplicity

The numbers in which the Grand Caravan has been produced and the minimal differences the latest EX bears compared to the original model stand testament to the designers ‘getting it right’ in the first place.

It is a relatively simple aircraft, but able to perform a broad range of roles with reliability and cost efficiency. It could be anticipated that a commercial pilot with some hours in the logbook could transition onto the aeroplane without too much difficulty. This not only reduces training costs but allows the Caravan EX to comfortably slot in as the turboprop flagship of an otherwise piston-engined fleet.

From its favourable handling characteristics and operating envelope to its practically thought-out nose gear assembly and exhaust system, the Grand Caravan EX exudes exquisite simplicity in an aircraft that will please those who operate them as well as those who are fortunate enough to fly them.

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