Turbine Pilot: Pilatus' Apex

A stately heavy hauler gets new glass

October 1, 2008

With sales nearing the 800 mark, the Pilatus PC-12 has been a standout in the single-engine turboprop market. Because the external features of the airplane remained largely unchanged during its 14-year production run, it can be tempting to believe that today’s PC-12 is the same as those of yore. Wrong. In 2006, with the series-10 versions, the airplane had a 1,411-pound gross-weight increase that allowed operators to top off the tanks and fly six passengers 1,400 nm with IFR reserves. At the same time, roll response was boosted by the addition of servo tabs to the PC-12’s ailerons, and many switches (ice protection, external lights, fuel pump, ignition, and starter) were moved from the lower instrument panel to the overhead panel. New Ipeco seats, with headrests, adjustable lumbar and thigh support, and deeper center cutouts (for greater ease in entering the cockpit) improved pilot comfort on longer trips.

TURBINE AIRWAYS: TEX departure

Flying America’s highest commercial airport

By Mark Twombly


Departure planning takes on a whole new meaning when it comes to flying a multiengine turbine-powered airplane. Analyzing field elevation, wind, temperature, and aircraft takeoff weight and configuration to determine if there is sufficient runway to meet normal two-engine takeoff requirements is just the beginning. The pilot in command must also consider climb performance, including engine-out, to a safe altitude. That’s easy enough when the runway is long, the field elevation is low, and the surrounding terrain is benign. And then there’s TEX—Telluride, Colorado, Regional Airport.

The challenge for pilots taking off from TEX is euphemistically summed up on the home page of the airport’s Web site: “Telluride Regional Airport sits atop Deep Creek Mesa and is North America’s highest commercial airport. [Emphasis is theirs.] At 9,078 feet above sea level, the airport offers picturesque views of the San Juan mountains.”

A few more eye-popping facts: The single runway, 9/27, is just 6,870 feet long, has a 64-foot-deep dip in the middle, and is bordered by mountains “in all quadrants” that tower above 14,000 feet msl. Throw in weather that may hide some of that bristling cumulo-granite, and you’ve got yourself some serious departure planning.

We arrived at TEX in ideal conditions—a brilliantly clear and calm August day. Despite being a nontowered, high-altitude airport with a relatively short runway in the thick of some of the highest peaks in the country, the ramp was chock-a-block full with airplanes ranging from piston singles and heavy corporate iron to a twin-turboprop Beech 1900 regional transport.

We were flying a Cessna Citation 550—a Citation II. It’s the Skyhawk of business jets, which is a high compliment. As jets go it is simple and therefore reliable, it has generous baggage space, the straight wing delivers low takeoff and landing speeds and distances, and with a gross-weight-increase modification we can fill the tanks with 5,000 pounds of fuel and fly for nearly four hours with a half-ton of people and bags aboard. The payback for that versatility is modest climb and cruise performance, as celebrated in its “Slowtation” and “Near Jet” nicknames.

Modest performance when operating out of a high-altitude airport in mountainous terrain calls for close attention to takeoff weight and conditions. Fortunately, for our next leg we would have but one passenger—an employee of one of the owners of the jet—and a 36-minute flight to Eagle County Regional (EGE) near Vail. We had managed our fuel upload at the two stops we made prior to TEX so that we could depart for Eagle County with only required fuel aboard plus a comfort factor.

Next on the planning checklist were takeoff minimums and departure procedures. A notam was in effect calling for takeoff minimums of 1,500 and three or standard (the weather was much better than 1,500 and three that day), with a minimum climb of 450 feet per nautical mile to 12,000 feet—a 7.5-degree climb gradient. The notam also specified a special obstacle departure procedure that basically called for a climb to 12,000 feet on a westerly heading to the Cones VOR some 17 miles to the west. (A commercial vendor, Aircraft Performance Group, designs customized engine-out obstacle avoidance procedures that in many cases have less restrictive climb requirements than the published departure procedure, but at the time we did not subscribe to the fee-based service. See http://apg.aero/.)

With both Pratt & Whitney JT15Ds running smoothly we would have no trouble climbing 450 feet per nautical mile to 12,000, which equates to a climb rate of about 900 feet per minute at a ground speed of 120 knots. However, if one engine popped at V 1 or later, the climb rate would fall far short of the minimum required gradient. Fortunately, the notam and the prevailing weather provided some relief by allowing for a climb in visual conditions to 12,000 feet. That we could do on one engine. Our planning indicated we were good to go on both runway length and the initial climb requirement, including for engine out. So far so good.

When we called for our clearance to EGE, the routing was “as filed,” which meant we could take off and turn north direct to Montrose VOR (MTJ). That prompted a crew discussion. The problem with flying the clearance was that higher terrain just to the north of the airport was obscured by clouds. It would have been suicidal to turn north into clouds coddling high terrain. And what if we lost an engine after takeoff? The only sane option was to fly the special Cones One obstacle departure procedure that was detailed in the day’s notams.

In retrospect, we could have avoided the momentary confusion over the “as filed” ATC clearance by including the Cones One departure procedure in our routing when we filed the flight plan. Even though the clearance we were given did not include Cones One, the only way for us to ensure that we would avoid any rocks hidden in cloud was to fly the published departure procedure. In fact, the Aeronautical Information Manual states that obstacle departure procedures “may be flown without ATC clearance unless an alternate departure procedure (SID or radar vector) has been specifically assigned by ATC.”

So Cones One it was. After taking off from Runway 27 we continued west, climbing to 12,000 feet on two healthy motors. Before we could center the needles on Cones the controller gave us a step climb followed by a turn north to MTJ. The short flight was uneventful from start to finish, which is just the way we like it.

Mark Twombly flies a Citation II and a Citation VII based in southwest Florida.

Now there’s the new PC-12NG. This is the most ambitious upgrade to the PC-12 ever, because it revolutionizes the instrument panel. The NG (for Next Generation) models use the much-awaited Honeywell Apex avionics suite—Honeywell’s answer to the groundswell of Garmin G1000 popularity. After a false start two years ago, Honeywell got the kinks out of the Apex software, and now Pilatus is the launch customer for the Apex. First deliveries of the NG airplanes—which begin with serial number 1001—have begun. So far, nine have been delivered, and Pilatus expects 73 more NG deliveries by year-end.

Joystick rules

The standard Apex panel has a single primary flight display (PFD) and two multifunction displays (MFDs). A second PFD is optional. The PFDs use the usual vertically oriented airspeed, altitude, and vertical speed tapes. What’s unusual is the presentation of engine instrumentation, and navcom, ADF, and transponder frequency selectors within the PFD field. Most glass cockpits put this information on a separate display. The Apex gives you this critical data front and center.

The MFDs are unique, too, in that they require the use of a joystick to activate cursor controls, navigate many menu fields, and select various inputs and functions. The joystick—a smallish stalk on the MFD keypad—is quite sensitive to even the smallest movements. It’ll zoom this way and that as you make your first attempts at menu navigation.

The top MFD, with its INAV (integrated navigation) functions, gets a workout every time you fly. You use the aircraft-on-ground, in-climb, and in-descent icons to call up menus on the left side to set up and amend your flight plans, do your weight buildups, and display takeoff, cruise, and descent information. The first step, as always, is to move the joystick so as to position the target-style crosshairs on the appropriate icon, and then hit the “Enter” button on the FMS keypad. Up pops a menu of options, and from there it’s move the crosshairs, hit Enter, then hit “Activate.” You get the idea. There’s a lot of crosshair moving, and it takes a while to get used to this method of data entry. Those with experience solely in line-select or trackball-style data entry will have to endure a learning curve. My demonstration pilot, Pilatus’ Peter Duncan, claims to have mastered the Apex in just 10 minutes (“When I found the ‘amend route’ entry on the drop-down menu, I was over the hump,” he said), but I think the average Joe Pilot will take a couple days—and maybe 20 hours of flying—before running the Apex becomes intuitive. SimCom’s Orlando training facility now has an Apex-equipped simulator. The pilot initial training takes six days. Trainees get two Apex training CDs in advance, so they can practice Apex procedures on their personal computers.

It’s worth pointing out that a lot of joystick commands aren’t necessary. The crosshairs automatically jump to the next sequential entry point. For example, if you hit Enter with the takeoff icon selected, the crosshairs immediately jump to the runway and standard departure options, and the takeoff V-speed boxes automatically pop up. Enter the desired runway and SD, enter the V-speeds, and then the crosshairs jump to the Activate button. Hit Enter and you’re finished with this phase of flight planning.

The Apex also lets you use the moving map display to rubberband a route around a storm cell, or amend instrument departure or arrival procedures. The map will also depict XM WX datalink weather and Stormscope returns and show terrain proximity via the ship’s terrain avoidance and warning system (TAWS-B) system, and traffic can be selected to show up on both the MFD and PFD.

The bottom MFD has “focus fields” that issue cautions and warnings, show systems information for the landing gear, flap, and trim positions, plus data on the fuel, electrical, and pressurization systems. Jeppesen electronic charts, when certified for installation by year-end, will also be available.

More power, please

The Apex isn’t all that’s new with the PC-12NG. Thermodynamic engine power has been bumped up from 1,600 to 1,744 shp, but the new Pratt & Whitney PT6A-67P (the “P” is for Pilatus) retains the former engine’s flat-rated takeoff power of 1,200 shp. This means a higher interturbine temperature (ITT) redline (820 degrees Celsius versus the previous 760 degrees), more protection against inadvertent redline excursions, and better hot-and-high performance. Pilatus also claims a higher max cruise speed of 280 knots. “But you can fly at 270 knots all day long,” a Pilatus official said, implying that 280 knots might only be achievable under the most advantageous conditions.

At FL260 and ISA +2 degrees C, Duncan and I saw a max cruise fuel burn of 377 pph, or 56 gph. In exchange, we trued out at the predicted 270 knots. On the other hand, even with our partial fuel load of 1,500 lbs/223 gallons we could fly for four more hours, covering some 972 nm. Of course, you could elect to fly at “combat cruise,” meaning with power set for an ITT just below redline. This would get you a true airspeed of 284 knots while burning 411 pph/61 gph. That’s at FL260, under these conditions, when time is of the essence.

The extra power also brought about a max takeoff weight increase. It’s now 10,450 pounds, up from the previous model’s 9,920 pounds. Payload with full fuel is up to 1,029 pounds. This means that a PC-12NG flying at FL300 can fly a pilot and three passengers 1,573 nm at max power—and land with NBAA IFR reserves. Virtually all PC-12s sold in the United States have the swanky six-place executive interior designed by BMW DesignWorks USA.

What you’d expect

The NG models have other thoughtful improvements. A major one is the addition of a second 300-ampere/hour generator. In earlier PC-12s, the number-one generator put out 300 amps, but the max output of the secondary, belt-driven generator was only 130 amps. This meant, among other things, that if you lost the main generator you’d have to leave icing conditions immediately. The secondary generator couldn’t deliver enough power to heat the ice protection system. Having two 300-amp generators does away with this restriction, and provides redundancy for the Apex’s current draw.

There are new “nice to have” features too, such as hotel and rental car information in the Apex’s airport database, footrests for the two aft cabin seats, and adjustable headrest bolsters.

But let there be no doubt: The Apex is the star of the show. As a derivative of Honeywell’s big-iron Epic avionics suites, the Apex has room to grow, Pilatus says. If so, expect infrared (enhanced) and synthetic vision as future upgrades. For those whose idea of a “real” airplane includes an airstair door, a lavatory, and an overhead panel, this all adds up to what many believe is the ultimate turboprop single.

E-mail the author at tom.horne@aopa.org.

SPEC SHEET

Pilatus PC-12NG
Average equipped price: $4 million
Specifications
Powerplant Pratt & Whitney PT6A-67P, 1,200 shp
Recommended TBO 3,500 hours
Wingspan 53 ft 4 in
Wing area 277.8 sq ft
Seats (Executive interior) 2+6
Cabin length (excluding cockpit) 16 ft 11 in
Cabin width 5 ft
Cabin height 4 ft 10 in
Basic operating weight (includes 200-lb pilot) 6,757 lb
Max ramp weight 10,495 lb
Max takeoff weight 10,450 lb
Max payload 2,283 lb
Payload w/full fuel 1,029 lb
Max landing weight 9,920 lb
Fuel capacity 2,704 lbs (402 gal)
Baggage capacity, internal, aft compartment 40 cu ft, 400 lb
Performance
Takeoff distance over 50-ft obstacle 2,650 ft
Initial rate of climb 1,920 fpm
Cruise speed/range w/NBAA fuel rsvn (fuel consumption), 30,000 ft
@ High-speed cruise power setting 269 kt/ 1,573 nm (349 pph/52 gph)
Max operating altitude 30,000 ft
Cabin altitude @ 25,000 ft 8,000 ft
Landing distance over 50-ft obstacle (max landing weight, w/reverse) 1,830 ft
Limiting and Recommended Airspeeds
V X (best angle of climb) 120 KIAS
V Y (best rate of climb) 130 KIAS
V LE (max gear extended) 240 KIAS
V LO (max gear operating) 180 KIAS
V MO (max operating speed) 240 KIAS
V S1 (stall, clean) 95 KIAS
V SO (stall, in landing configuration) 66 KIAS
For more information, contact Pilatus Business Aircraft, Ltd.; Rocky Mountain Metropolitan Airport Airport, 11755 Airport Way, Broomfield, Colorado 80021; 303-465-9099; www.pilatus-aircraft.com.

All specifications are based on manufacturer’s calculations. All performance figures are based on standard day, standard atmosphere, sea level, gross weight conditions unless otherwise noted.