Beechcraft King Air 350i

By Fred George fred_george@aviationweek.com
Source: Business & Commercial Aviation

The Model 350i made its production debut in 2009, featuring much-improved interior soundproofing, a Rockwell Collins Venue IFE system, Raisbeck dual aft body strakes and Raisbeck wing lockers in the nacelles.

The aircraft's 1940 vintage, NACA 23000 series airfoils are considered dated by many modern aero purists. But Beechcraft aerodynamicists point out that the time-proven airfoil offers a good blend of stall characteristics, relatively low performance degradation in icing conditions and good lift-to-drag characteristics in the turbulent wake of the aircraft's twin, four-blade, 105-in. props throughout the flight envelope. If King Airs had pusher configuration turboprops or turbofans, then other airfoils might be better suited to the aircraft.

The 310-sq.-ft. wing has a 10.8:1 aspect ratio and it is built in three pieces. The center section includes the left and right engine nacelles and it uses a constant 23016.5 cross section airfoil. Compared to the Model 200/B200, the leading edge of the center section was extended and recontoured for the 300 and 350, resulting in more elliptical lift distribution throughout the flight envelope. The inboard leading edge change both reduces induced drag and wing bending moments at normal cruise speeds.

The left and right outboard wing sections are bolted to the center section outboard of the nacelles. They have 6 deg. of dihedral to enhance stability and to promote transfer of fuel. They feature modest geometric and aero twist, tapering down to 23012 airfoils near the tip. Winglets improve the aircraft's lift-to-drag characteristics at relatively high lift coefficients, such as during takeoff and landing. That improves OEI takeoff performance.

The addition of Raisbeck Engineering dual aft body strakes considerably im–proves yaw stability. The strakes allow the aircraft to be dispatched and flown at altitudes up to 19,000 ft., versus 5,000 ft. for an unmodified aircraft, with an inoperative yaw damper.

The primary flight controls are man–ually actuated by means of cables and pulleys between the control yokes and rudder pedals and the flight control surfaces. Control forces are neutralized with trim tabs on the left aileron, rudder and both elevators. The aircraft has electric pitch trim and manual pitch, roll and rudder trim. An electric rudder servo provides yaw damper and rudder boost functions. When the difference in engine torque output between the engines exceeds 30%, the rudder boost function helps deflect the rudder proportionally to the difference in engine output to reduce the pedal effort needed to offset yaw.

The four-section Fowler flaps are actuated by an electric motor. The flap lever in the center console has up, approach and down positions. Intermediate positions cannot be selected.

Left and right, 300-amp starter generators and a 42-amp/hour sealed lead-acid battery provide three power sources for the 28-VDC electrical system. A ground power cart can be connected to the aircraft by means of a receptacle under the wing outboard of the right engine nacelle.

In normal operation, the left and right generator buses, plus the battery-powered center bus, all are connected in parallel. The left and right generators share loads equally. The relay ties between the buses only open in the event of a malfunction.


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