The 350i is easy to taxi because of differential thrust, smooth brakes and effective nosewheel steering via the rudder pedals. Holding short of Runway 32, we commenced the litany of first-day pre-takeoff checks, including electric pitch trim, prop overspeed governor and rudder boost, low-pitch stop and primary governor, autofeather and engine anti-ice systems. Wuertz says the checks can be done quite quickly with some practice, but it would be advisable to run through them before boarding passengers who have paid for a flight. Various fuel system, cabin altitude, landing gear and fire-protection checks must be completed. Brake deice, traffic collision avoidance and terrain awareness system checks are performed before each flight.
Once cleared for takeoff, we advanced the power to about 85% torque as we began the takeoff roll. The pitot cowl inlets are so efficient at converting air velocity into air pressure that torque increased 5% during takeoff roll. We adjusted power to 100% torque. As the engines accelerated to 1,700 prop rpm, aircraft interior noise levels rose accordingly; it was not particularly quiet. I also noticed we spent considerable time cross-checking engine output and making minor adjustments to set takeoff power. Clearly, the Pratt & Whitney Canada PT6A-60As are long overdue for a full-authority digital electronic control (Fadec) upgrade to reduce pilot workload.
Rotation force was light, as was roll-control force. The Beechcraft standard for gentle and progressive control force far exceeds any certification requirement. With a positive rate of climb, we retracted the landing gear with virtually no pitch-moment change. There was a small lag in the response to inputs to the pitch-trim switch. The manual pitch-trim wheel provided immediate response, but a comparatively small amount of rotation results in a large change in trim.
Pulling back the throttles to 95% torque and setting the prop levers to 1,500 rpm reduced the interior noise considerably. Clearly, the sound-suppression system is tuned to 100-hz noise, the prop frequency at that speed. The reduction from takeoff to climb power results in a significant change in yawing moment, requiring left rudder input and corresponding rudder trim to maintain balanced flight. A similar change in yawing moment came as we reduced power after level-off at cruise altitude. And the yaw damper does not compensate much for such changes.
We had planned to reach a cruise altitude of 7,000 ft. in 10 min. for our brief flight to Morristown, N.J., but air traffic control kept us at 4,000 ft. for the 93-nm jaunt. We settled into a 200-kt. cruise below the floor of Philadelphia Class B airspace. Operating at low altitude, at this speed, the King Air 350i shows off its big advantage in fuel efficiency over similarly sized turbofans. “In this area, this airplane operates so much cheaper than a jet and you're doing the same thing that the jets do. They can't get high, either,” Wuertz said. At a weight of 12,700 lb., cruising at 200 kt. at 4,000 ft. in 17C conditions, the aircraft burned 730 lb./hr.
Once clear of the shadow of Philadelphia's Class B airspace, we accelerated to 250 kt.“Easy on the power,” cautioned Wuertz, as we fine-tuned the throttles to avoid exceeding 100% torque. PT6A engines tend to be sensitive to throttle movements at higher power settings, and the response is anything but linear. At 12,500 lb., the aircraft settled into cruise at 250 KIAS (266 kt. true airspeed) while burning 1,020 lb./hr.
Approaching the floor of New York's Class B airspace, we slowed back to 200 KIAS. Wuertz entered Morristown's Runway 23 instrument landing system (ILS) approach into the FMS for reference purposes. The FMS automatically tuned to 110.3 mhz for the ILS approach, and the PFD displayed the 229-deg. inbound localizer course in the preview mode.
Changes in power, and therefore fuel flow, result in simple time/distance/fuel-remaining computations by the FMS. Unlike most jets, the FMS in this aircraft is not sophisticated enough to consider expected climb, cruise, and descent fuel burns and speeds when computing fuel remaining at the destination. “It's just like a calculator. You punch it in and that's what it's telling you,” Wuertz explained.
On downwind, Wuertz switched on the aircraft's optional nose-mounted, infrared enhanced-vision-system camera. This is a microbolometer design that is good for thermal imaging at night or in partial obscuration. The technology much improves situational awareness when flying “black hole” approaches, particularly where obstacles in the final approach path pose potential hazards.