Putting The Extra In The Cessna Caravan
More horsepower is the answer to a lot of aviation shortcomings. The venerable Cessna Caravan, after 30-plus years in production, has grown into a dependable workhorse, seen all over the world in utilitarian roles. But there’s always a desire for a little more…payload, climb, takeoff capability…the usual list.
As with any good airplane, there are always going to be aftermarket add-ons to satisfy such desires. And such has been the case for the Caravan. Meanwhile, Textron Aviation’s Cessna division could see the need for a further power upgrade for its stretched Caravan 208B, which had already gone from 600 shp to 675 shp with the PT6A-114 engines. This time, they added nearly 200 more horses, dropping in a PT6A-140 that churns up 867 shp. The result is the Grand Caravan EX.
Now, if you think you know Caravans, the sturdy servants of package hauling, bush flying, tourist trips, skydiving drop zones and seaplane operators, be aware that the old 208 has gone through several generational changes over the years. First, of course, was the lengthened fuselage of the windowless Federal Express cargo van, then the boost to 675 shp, initially in the longer Grand Caravan, then in both models. The Wipline amphibious floats transformed the Caravan into a fine waterplane, and the Garmin G1000 instrument panel brought the stodgy steam-gauge front office into the modern age. And Yingling Aviation’s Oasis executive interior has created a posh environment for owners who don’t intend to go roughing it.
At this point, you can have your Caravan just about any way you want it. The short-cabin Caravan 675 remains in the product line, if 340 cubic feet of cabin cargo space isn’t required, but the longer Grand Caravan is popular for its ability to handle a combination of passengers and cargo.
Prior to NBAA BACE 2016, we were given an invitation to come to the Wichita, Kansas factory to sample the Grand Caravan EX, with its latest appointments. After waiting out some late-summer thundershowers, which gave us a chance to reacquaint ourselves with the 208B in the shelter of its hangar, the skies broke open with the beautiful Midwestern blue we had been promised.
As Jon Grief, demonstration pilot and training specialist, showed us around the big turboprop, we were reminded of both its size and its simplicity. For all its bulk, it’s still a strut-braced high-wing fixed-gear single, like its smaller siblings in the Cessna line. When Cessna laid down the lines for the Caravan, it already knew a lot about making utility airplanes. Fixed gear is more rugged than retractable wheels, and keeping the wing out of the way of loading and obstructions is important. Cessna just scaled up the 206, for the most part.
To differentiate the 208B from the original Caravan, look for a bulge above the cockpit door, forward of the wingroot; the smaller 208 has the wing leading edge in that location. And there are seven side windows instead of five, thanks to four feet of extra fuselage length. A big plane needs a big powerplant, of course, and turbine power is the answer for needs of more than 350 horsepower or so. The Pratt & Whitney Canada PT6A was the choice from very beginning; the 867-shp engine in the Grand Caravan EX takes up no more room than the earlier engines, and it allows the gross weight to grow to 8,807 pounds, a slight increase over the old 208B to preserve useful load.
There are a few changes under the cowling with the new –140 engine; the fuel filter bypass indicator is now checked on the right side of the engine, rather than the left. The old messy EPA can, mandated to catch the small spurt of unburned Jet-A at shutdown, is gone, replaced by a recycle system that simply burns the leftover fuel at the next start-up. And because our demo bird had the optional 300-amp generator (in addition to a standby alternator) there was extra ductwork to cool the big dynamo.
There’s a lot of thought in the Caravan’s design, oriented toward keeping it running out in the field. The lead-acid battery is easily serviced, or removed, by swiveling it away from the firewall on its mounting. The hinged cowling halves prop up to keep them off your noggin, and the cockpit doors have restraint rods to hold them from banging forward in the wind while you’re working under the hood up front. The ignition exciter box is vital for starting, so an extra unit can be carried on a mount provided beside the primary box; all you have to do is switch three Cannon plugs to get home.
The massive three-blade Hartzell propeller has a diameter of 106 inches, with plenty of ground clearance; a four-blade McCauley Blackmac prop is an option. The well-braced nosegear is mounted right behind the propeller disc to protect the prop when negotiating dips in rough ground. The demonstrator’s maingear, which flexes on long maintenance-free springs, was fitted with the optional 29 x 11-10 high-floatation tires in place of the standard 8.50 x 10 tires. For all its off-road capability, the subject airplane was equipped with a vapor-cycle air-conditioning system, very welcome in the tropics. Heating is provided by warm compressor bleed air, modulated by a heat exchanger.
Fuel is carried in integral tanks in the wings, all 335 usable gallons of it. It’s usually burned simultaneously, but individual valves allow one side to be shut off for parking or balancing. For the floatplane kit, inboard fuel fillers are provided to facilitate more convenient dockside refueling, reducing fuel capacity to 240 gallons.
For a single, the airplane casts a large shadow. The 280 square feet of wing area spans a tad over 52 feet; even the horizontal tail is 20 ½ feet wide. The rudder tip is just over 15 feet above the ground. Without its typical cargo pod under the belly, the Grand Caravan EX has a greyhound look on the ramp. Most operators will want the pod’s four bins of extra space. The demonstrator aircraft had the TKS anti-icing system installed, with a 20-gallon tank of fluid installed in the second pod compartment; the tank is anchored to the fuselage structure, not the pod floor, and two pumps are installed to make sure the fluid is available when needed. About 3.4 hours of dispersal is provided in “normal” mode, with a full tank.
The massive wing has pitot/static masts on both sides, with two landing/taxi lights per side, and an optional weather radar pod goes on the right leading edge. To keep the stall speed in landing configuration from exceeding the 61-knots of Part 23 certification, extra-wide Fowler-type flaps are installed, with vortex generators molded into a rubber strip on the outboard section, aft of the roll-control spoilers, and an added Gurney strip keeps airflow attached at the trailing edge. The wing’s upper surface has a row of vortex generators behind the leading edge. The ailerons alone are not sufficient for control at low speed, even with servo tabs, so a spoiler actuates with up aileron travel. Trim is provided on the right aileron, the rudder is trimmable and both elevators have trim tabs. To enhance pitch control, vortex generators are on the horizontal stabilizer. An external rudder lock handle, transplanted from the twin Cessnas, lifts up to secure the rudder when parked; if not released, up elevator travel disconnects the lock.
Given the chest-high cabin floor, the obvious question is “how do you get in?” The Caravan opens up like a utility knife kit; passengers climb aboard via a two-piece three-step airstair on the aft right side of the fuselage, cargo is loaded through a huge 50-inch opening on the left side, the lower door hinged to fold flat for uninhibited access, and two crew doors up front allow pilots to enter even with the cabin stuffed full. Agility is a prerequisite; boarding ladders fold down to facilitate the ascent. Rain gutters are installed above all the doors.
Once Jon and I were ensconced, I raised my gangplank (er, ladder) to secure the door. The cockpit, like everything else about the airplane, is big; the three G1000 displays hardly make a dent in the panel space and there’s enough room to slip aft between the seats. Looking behind, the double-club seating arrangement in our aircraft was only one of the possible interior arrangements (only the two crew seats are standard equipment). U.S. Part 23 regulations only permit nine passenger seats, but up to fourteen total seats are often ordered by export customers, utilizing an aft bench.
The spacious cockpit has a waterfall of circuit breakers on the left sidewall and panel, with starting and electrical switches nearby. The overhead is used only for fuel valves, loadmeters and rheostats, oxygen controls and a control lever for the standby flap motor, in case the primary motor goes out. The center pedestal has trim wheels, the flap switch, throttle, prop and condition levers, and a manual fuel control lever for emergency operation—everything except a landing gear handle.
Reliable mechanical standby instruments are arrayed above the power quadrant. Panel vents are fed by air inlets on the forward fuselage, while the cabin’s overhead system is supplied by vents at the top of the wing struts. The big single exhaust diverts soot and gases away from the cabin.
The Garmin G1000 flight deck, with the GFC-700 autopilot, remains Textron’s choice for the Caravan, given the back-country utility mission, where bulletproof reliability is paramount. Dual AHRS (attitude and heading reference system) and air data computers are installed, and we had terrain, traffic and Safe Taxi available, along with dual audio panels to avoid reaching across.
Firing up is typical PT6A procedure, except the generator comes on line automatically when the starter is turned off. Fuel boost on, we lifted the start toggle and observed 12% Ng before going to low idle with the condition lever. After accelerating to 52% Ng the starter was moved to off and avionics came on. Moving out of the ramp requires attention to the plane’s size, even if it’s a high-wing single. The big engine powered us along in taxi with little urging, and some restraint from Beta, or even reverse, was helpful. There’s a lot of throw in the hefty rudder pedals; the Caravan can swing around in under 33 feet, if persuaded.
Pretakeoff checks included a test of the overspeed governor at 1,750 prop rpm and unlocking and deploying the manual inertial separator handle at 400 ft/lb torque to make sure it works. That’s about it; the G1000 already had our flight plan to Wellington, Kansas, south of ICT. Flaps are normally set to “approach” for takeoff; earlier Caravans had detents for 10, 20 and 30-degree positions, but the EX was simplified to “app” and “full”, the 20 and 30-degree points. Naturally, you can select any mid-position you desire.
Redline power is 2,347 ft/lbs., so moving the power-lever to about 2,200 was sufficient. Takeoff weight was just under 8,000 lbs. There’s no need to delay liftoff, initiated at 74 knots. Flaps came up at 95 knots and Vy is 108 knots. The EX climbed out at 1,500 fpm; for quietness, climb procedure normally reduces prop rpm to 1,800 rpm, from the 2,000 rpm takeoff setting.
There was no reason to climb high for the short run to Wellington; we leveled at 4,500 feet. Reducing prop rpm to 1,600 brought the torque up to 2,145 ft./lbs., with a profligate fuel flow of 420 pph; most Caravan flights are carried out at 10,000 feet or so, where fuel consumption is reduced to about 360 pph. The IAS settled on 157 knots, for a TAS of 170; without the belly pod, the EX will pick up another 10 knots.
Prior to landing, we conducted some handling checks, finding the big Caravan somewhat ponderous at cruise, which makes it a stable platform. Slowed down to pattern speeds, it lightens up considerably; however, the big pitch trim wheel must be spun when flaps are extended, which soon becomes an automatic reflex after moving the flap lever. A clean-configuration stall warning came on at 75 knots, breaking gently at 70; with full flaps, the warning came on at 65 knots and a little more enthusiastic break occurred at an amazing 55 knots.
The TCAS system warned us of inbound traffic, unseen but well announced. About 400 ft/lbs. slowed us to pattern speed and we came down the slot to the runway at 85 knots, finding the surface a little earlier than we thought, with the wheels far below the cockpit. Turnoff came in about 1,200 feet, with generous reverse thrust. Jon then suggested a short-field circuit, in which case we climbed out at a steep 86-knot Vx, easily achieving pattern altitude by runway end. This time, we approached at 80 knots, plunking the EX right on the numbers.
After sufficient enjoyment, we headed back to Wichita’s Eisenhower airport, where a “short approach” was requested, a good opportunity to see how the Grand Caravan EX fits in with fast traffic. Carrying 150 knots so we could extend approach flaps when desired, we steamed around onto final with 125 knots, the full flaps limit, and bled off speed to make the first exit. No problem.
The powerful Grand Caravan EX is exactly what a lot of long-body Caravan operators have been looking for. It preserves the short-field capability of the other 208’s, but can deal more success-
fully with high-and-hot conditions. And its friendly manners haven’t changed.