Pilot report: Long-legged King Air 350ER is a Flexible and Capable Turboprop

 - January 1, 2013, 4:30 AM
The core mission of the Beechcraft King Air 350ER is long range and lengthy loitering times, up to 2,650 nm or 12 hours.

The King Air 350i is now Beechcraft’s biggest airplane, but the 350ER version takes the turboprop twin a few steps further, adding enough extra fuel to stay aloft for up to 12 hours in loiter mode or power along at more than 260 knots for nearly 2,300 nm, all while carrying one pilot and six passengers and with NBAA IFR reserves. Maximum range is as far as 2,650 nm.

Beechcraft senior sales demonstration pilot Luke Scott and senior product marketing manager Roger Hubble made a stop at Santa Monica Airport on October 16 so I could fly the company King Air 350ER in special-mission configuration to Henderson Executive Airport near Las Vegas for the 2013 NBAA Convention.

While it was only a 58-minute flight for the big King Air, the trip afforded the opportunity to sample the 350ER’s low-speed and high-speed performance and how easy this sizable airplane is to fly. Flying to the NBAA show in a Pratt & Whitney Canada PT6-powered airplane was a bonus, making us feel like part of the 50th anniversary celebrations for the widely used turboprop.

Beechcraft has built more than 900 King Air 350s. The extended-range 350ER was certified in 2007, and Beechcraft will have delivered about 120 of that version by the end of this year, according to Hubble.

The 350ER has a few distinguishing characteristics that sharp-eyed pilots can use to tell the difference between the ER and the standard 350i. Small protuberances on the upper rudder add to engine-out control effectiveness with no increase in rudder area. The 350i has these bulges, too, but they are smaller than those on the 350ER. “It tricks the rudder into thinking the surface is longer,” Scott said, although the 350ER’s rudder actually is slightly longer and its trim tab moves farther than that of the 350i so both have similar handling characteristics.

The main landing gear struts are stronger versions with wheels, tires and brakes from the heavier Beech 1900D airliner. To accommodate the bigger wheels in the retracted position, the 350ER’s main landing gear doors are shorter and the wheels protrude into the breeze. A useful feature on the 350 models is brake de-icing, which ports bleed air onto tubes surrounding the brakes discs. “It’ll melt snow around the tires,” said Scott, and can be used with the wheels up or down.

Added Fuel Capacity

But the most visible difference is on top of the nacelles. Where wing lockers usually sit, bulbous fuel tanks are mounted, giving the nacelle the appearance of being inflated to hold more stuff.

The nacelle tanks are just two of the six tanks in the 350ER, and each holds 118 gallons of jet-A. Total fuel capacity is 5,192 pounds or 775 gallons, and the rest of the fuel fits into four wing tanks. “The ultimate objective,” Hubble said, “was to make the California-Hawaii run. If we can make that, we can go anywhere in the world without [fitting interior tanks].”

The 350 has the same wing as the B200T, but the 53-gallon tip tanks on the B200T add drag whether or not they’re carrying fuel. “We were looking for a lower-drag place to put fuel,” he explained, “and we wanted more fuel and the benefit of the winglets. The next logical place was aft of the engines.” The engineers considered composite tanks, especially for the ease of incorporating compound curves, but ultimately selected metal for the simpler lightning-strike protection. In any case, if just 50 gallons per side were needed, each wing locker could accommodate that amount, but an extra 100 gallons wouldn’t help much with the Hawaii-California mission.

With a maximum takeoff weight of 16,500 pounds (1,500 more than the 350i), the 350ER has a basic operating weight with one pilot of 9,520 pounds when equipped with the “slick” interior or 10,385 pounds typically equipped. When the aircraft (typically equipped) is carrying max fuel, payload is 1,023 pounds. The slick interior is the smooth-floored mission-ready interior without any cabinets or seats, easily convertible to a dual-stretcher air-ambulance interior or other configurations. With the slick interior, payload is 1,888 pounds. The slick interior’s cockpit center pedestal is the standard 17-inch unit, but this ER featured the extended 24-inch pedestal, which is available to house additional mission equipment controls that are available for the flight crew.

The fuel capacity beyond that of the 350i enables some long trips in the 350ER. Maximum range of almost 2,580 nm with a 45-minute reserve is obtained at 33,000 feet and max-range power, which delivers a true airspeed of 242 knots. On a trip from Calgary (Canada) with two pilots and six passengers and Boeing 85-percent-probability winds, maximum NBAA IFR range (100-nm alternate) for the 350ER is 2,130 nm–618 nm more than the 1,512 nm the 350i can muster under the same circumstances.

The modifications for the higher mtow and the bulbous nacelle fuel tanks do incur some penalty: at 24,000 feet the 350ER’s high-speed cruise at mid-weight is nine knots slower than the 350i’s 312 ktas. (The 350i is equipped with the flatter nacelle wing baggage lockers.) Fuel flow is 764 pph for the 350ER, slightly less than the 350i’s 773 pph. Long-range cruise speed at 33,000 feet is close to identical, 237 and 238 ktas for the 350i and 350ER, respectively, although the ER burns 402 pph, 40 more than the 350i.

Both models are certified to a maximum altitude of 35,000 feet, but the heavier 350ER has an all-engine service ceiling of 33,000 feet, 2,000 feet less than the 350i, and engine-out service ceiling of 17,100, compared with the 350i’s 21,500 feet. The 6.6-psi pressure differential maintains a sea-level cabin to 15,200 feet and cabin altitude climbs to 8,200 feet at 30,000 feet. At the 35,000-foot max altitude, cabin altitude is just above 10,000 feet.

The slick cabin makes it easy to swap out interior components, depending on the mission. Beechcraft’s special-mission 350ER demonstrator was equipped with a mockup control station and the optional belted forward-facing lavatory (the 350i has a side-facing lav). With the lav, baggage capacity in the rear cabin is 350 pounds, but without the lav that grows to 550 pounds. In the 3530ER slick interior, up to 13 seats can be installed in high-density configuration, which includes the belted lav, a folding chair and 11 lightweight (26-pound) Aviation Fabricators seats (half the weight of the executive seats). Vapor-cycle air-conditioning by Keith Products delivers 150 percent more cooling than the previous system, which on earlier 300/350s was retained from the King Air 200. The new system has dual climate zones for the cabin and cockpit.

Taxi and Takeoff

The Atlantic Aviation ramp at Santa Monica Airport is always tightly packed with business jets and turboprops, but taxiing the big 350ER with its 57-foot wingspan between the parked aircraft feels like moving a smaller airplane. We carried 2,500 pounds of fuel and were loaded to about 13,500 pounds. The 350ER, certified in the Part 23 Commuter category, takes off more like a jet, with similar requirements for takeoff field length and speeds. V1 was 98, V 101 and V2 109 knots. Takeoff field length with approach flaps set was about 3,800 feet. After I pushed the throttles forward so the torque needles pointed to the nine o’clock position, Scott did the fine-tuning to set maximum torque on the 1,050-shp PT6A-60A engines, and the King Air surged forward then lifted quickly skyward and steeply away from the noise-sensitive neighbors surrounding the airport.

I hand-flew the King Air to 14,000 feet and found the handling straightforward and comfortable. The long ailerons, which span about half of the length of each wing, are precise and responsive. The cable-tension regulators built into the flight controls help keep cables tight, which adds to the crisp feel.

We climbed to 21,000 for the short flight to Henderson. At cruise altitude, Scott demonstrated the max endurance configuration, and we slowed down, with torque set to about 30 percent and approach flaps. The airspeed settled on 120 indicated or 175 true and fuel flow was about 180 pph per engine. With our remaining fuel of 2,230 pounds, we could have flown for another five hours 45 minutes. With full fuel we could stay aloft for 12 hours 27 minutes, according to Scott, a good reason why Beechcraft includes a pilot relief tube in the 350ER cockpit.

With the power pushed up to 85 percent torque, fuel flow climbed to 400 pph per engine and speed to 216 kias/302 ktas at ISA +10 degrees C.

Scott demonstrated some features of the King Air’s Rockwell Collins Pro Line 21 flight deck, such as the datalink weather via the Iridium-based GWX-5000, which displays worldwide Universal Weather & Aviation UVdatalink information. (SiriusXM WX for the continental U.S. is an option.) Because of the clear weather in the Western U.S., we had to zoom out some distance to find graphical Nexrad images in the central U.S., but it was handy to be able to check local Metars and Tafs. A neat feature of the Rockwell Collins TWR-850 turbulence-detecting Doppler radar is that each pilot can control range, mode and tilt. This King Air also has the optional enhanced-vision system, with the Max-Viz EVS-1500 IR camera mounted on the top of the nose. EVS imagery appears on the center MFD.

Search Patterns

For search-and-rescue operations, the Pro Line 21 flight management computer is programmed with search patterns, such as a ladder search, and the FGC-3000 automatic flight guidance system will automatically fly the desired pattern. This 350ER’s standard equipment includes dual Collins FMS-3000s, Waas-LPV GPS receivers, Tcas-4000 Tcas II and ACSS Taws+. Backup instrumentation is provided by an L-3 GH-3100 electronic standby instrument system mounted to the right of the MFD, just above the RTU-4200 com/nav tuning unit. With its long-range capabilities, this 350ER is equipped with a single HF radio, which is also an option. To meet the upcoming 2020 mandate in the U.S. (and starting this December in some countries) Beechcraft is working with Rockwell Collins on ADS-B upgrades. Also optional is Aircell’s Gogo Biz air-to-ground Internet access and voice calling system.

For the added electrical needs of special-mission equipment, Beechcraft offers an optional 400-amp starter-generator, which provides filtered power to the cabin. Previously, some special-mission operators modified the 350 with a belt-driven 100-amp alternator that fed the cabin directly and wasn’t filtered through the airplane’s batteries.

The weather was CAVU as we flew over the massive BrightSource solar thermal electricity generating plant near the California-Nevada border and descended toward Henderson in the turbulence-free air. The approach flaps extension speed is 202 knots and the landing gear can go down at 182 knots. Our landing weight was 12,400 pounds and Vref 104 kias. The big King Air is easier to land if trimmed correctly, but I didn’t take as much advantage of the trim as I should have and made myself work harder to land smoothly on Henderson’s 35L.

The 350’s propellers are equipped with flight idle pitch stops. “This makes landing easier,” Scott said, “more like a jet.” After landing, the propellers shift into ground idle mode when the weight-on-wheels switch activates, then a little bit of prop reverse brings the King Air quickly to a stop with plenty of runway remaining.