Beechcraft King Air 90

In 1964, Beech introduced the Model 90 Beech King Air. It quickly established itself as the industry standard in corporate jetprops. During our production of Northwestern Air Lease a multitude of the King Air 90’s on board systems are reviewed. Below is an overview.

The engine is a reverse flow, free-turbine engine. Air enters through an intake screen and passes into a three-stage axial and single-stage centrifugal compressor driven by a single-stage reaction turbine. Another single-stage reaction turbine counter-rotating with the first drives the propeller through a two-stage reduction gear. Fuel is sprayed into the annular combustion chamber by fourteen individual removable fuel nozzles mounted around the gas generator case. A low voltage ignition unit and coil igniter plugs are used to start combustion. The fuel control unit schedules fuel flow to maintain the power set by the gas generator Power Levers. The accessory section and integral oil tank are located on the aft end of the gas generator.

Propulsion Systems and Controls
Operated by three sets of controls:

Power Levers: control engine power from idle to take-off power by adjusting the N1 speed governor in the FCU. Increasing N1 results in increased power.
Propeller Levers: Control the constant speed propellers through the Primary Governor.
Condition Levers: 3 position lever; CUT-OFF, LOW-IDLE, and HIGH-IDLE.

All three work in conjunction with the fuel control unit to control engine power. Propeller reversing is accomplished by lifting the power levers over the IDLE detent. The levers override the Secondary Flight Idle Stop and control engine power through the beta and reverse range.

Fuel System
The fuel system has a total capacity of 384 usable gallons, consisting of 131 gallons in each wing tank and 61 gallons in each main take. Both the right and left had systems are independent of each other and are connected only by the cross-feed system. Fuel under pressure is supplied to each engine by a submerged boost pump in each main tank.

Electrical System
The direct current, 24 volt electrical system consists of a single, 24-volt, 40 ampere/hour, nickel-cadmium battery mounted in the right center section and two, 200-ampere starter generators controlled by solid state regulators.

Flight Controls
Conventional dual controls are provided and nose steering is accomplished by use of the individually adjustable rudder pedals. Trim tabs on the rudder, elevator and left aileron are adjustable from the center pedestal. Optional electric elevator trim is thumb-actuated by a switch on the pilot’s control wheel.

Three-position switch
UP - 0%
DOWN – 100%

Landing Gear
The landing gear is retracted and extended by a 28-volt split field motor. Safety switches are incorporated to prevent inadvertent gear retraction on the ground and to avoid gear up landings. Visual indication of the landing gear position is provided by individual green lights for each gear. Gear Unsafe lights are installed.

Hydraulic disk brakes on each main wheel are controlled via pilot toe pressure on either set of rudder pedals.
Pressurization System
The pressurization form the cabin comes from a mechanically driven supercharger connected to the left engine accessory case. An air to air heat exchanger removes the heat from this air prior to entering the cabin.

  • TYPE: Beech 90 Airliner
  • FIRST BUILT: 1968
  • COUNTRY OF ORIGIN: United States of America
  • ENGINE: Pratt and Whitney –28 Oil Capacity (each engine): 3.5 gallons
    • Wing span: 45 ft 10.5 in
    • Length: 35 ft 6 in
    • Height: 14 ft 2.5 in
    • Propeller Diameter: 7 ft 9 in
    • Wheel Base: 12 ft 9 in
  • WEIGHTS A/B 90:
    • Max. Takeoff Weight (MTOW): 9,300 lbs
    • Max. Landing weight (MLW): 8,835 lbs
    • Operating Empty Weight (OEW): 5,600 lbs
    • Maximum Payload: 3,700 lbs
    • Maximum Fuel Capacity: 2,540 lbs
  • WEIGHTS C 90:
    • Max. Takeoff Weight (MTOW): 9,650 lbs
    • Max. Landing weight (MLW): 9,168 lbs
    • Maximum Ramp Weight (MRW): 11,500 lbs
    • Maximum Payload: 3,700 lbs
    • Maximum Fuel Capacity: 2,540 lbs
    • Wing Fuel: 870 lbs / Nacelle Fuel: 400 lbs
    • Maximum Cruise Speed: 225-235 kts
    • Range: 1150 NM
    • Typical Fuel Burn: 550 lbs / hr
    • Maximum Cruise Altitude: 30, 000 ft
    • Seats: 6 passengers plus 2 crew ft


Visit the Northwestern Air page to learn more about our new DVD featuring the King Air 90





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