At the end of November 1983, coinciding with the 25th anniversary in airline service of the twin-turboprop F27 Friendship, Fokker announced follow-on developments of both the F27 and the twin-turbofan F28 Fellowship, to be known respectively as the Fokker 50 and Fokker 100. Both aircraft build on successfully proven airframes, but with significant design and structural changes, allied to more efficient (and more fuel-efficient) power plants, increased use of composite materials, greater passenger comfort and convenience, advanced digital avionics, and improved airport handling characteristics. In consequence, more than 80 per cent of the component parts of the Fokker 50 are new or modified by comparison with those of the F27.
The two prototypes of the Fokker 50 utilised modified F27 fuselages rather than the redesigned fuselage of the production aircraft. The first of them (PH-OSO) flew for the first time on 28 December 1985, and the second (PH-OSI) on 30 April 1986; the first production Fokker 50 (PH-DMO) flew on 13 February 1987, and certification was granted by the Dutch RLD on 15 May 1987.
In the production aircraft, differences from the F27 include new-technology engines, in redesigned nacelles, with six-blade propellers; use of carbon, aramid and glassfibre composites in such areas as the wings, tailplane, fin, radome, engine nacelles and propellers; passenger door relocated at the front of the aircraft, and the large cargo door deleted; more windows in the passenger cabin; pneumatic system replaced by a hydraulic system; and a cruising speed some 12 per cent higher than that of the F27. Seating range is 46-58, with 50 as standard, but the cabin offers considerable flexibility for other layouts, including ample accommodation for baggage and freight. The production programme is shared with Dassault-Breguet (centre and rear fuselage sections), Fuji (rudder and elevators), MBB (wing trailing-edges/control surfaces, tailcone and dorsal fin), and Sabca (outer wing skins and wingtips).
Firm orders for 43 Fokker 50s had been received by June 1987, from Ansett of Australia (15), Austrian Airlines (2), Busy Bee of Norway (4), Corsair of USA (7), DLT of West Germany (7), Maersk Air of Denmark (4) and Sudan Airways (4). First delivery, to DLT, was made on 7 August 1987.
TYPE: Twin-turboprop short-haul transport.
WINGS: Cantilever high-wing monoplane. Wing section NACA 644-421 (modified) at root, NACA 642-415 (modified) at tip. Outer panels have 2° 30' dihedral and 2° washout. Incidence 3° 30'. No sweepback. All-metal riveted and metal-bonded two-spar stressed skin primary structure, consisting of centre-section and two detachable outer wings. Detachable AFRP leading-edges with rubber boot de-icers. Trailing-edge skins are of composites material, supported by ribs of composites or metal construction. Single-slotted all-metal trailing-edge flaps (two segments per wing, divided by engine nacelle), operated by spindle/drive-nut. Flaps are actuated hydraulically, with electrical backup system, and are mechanically interconnected. Aileron structure is formed by bonded skin/stringer assemblies riveted to front, centre and rear spars and ribs, with leading-edges of composites material. Ailerons are actuated mechanically via cables. Each has an inboard spring tab and outboard geared/balance tab; starboard balance tab serves also as an electrically operated trim tab. Horn balance, known as Foklet, of metal reinforced composites, at each wingtip to increase lateral stability at low airspeeds.
FUSELAGE: All-metal stressed skin primary structure, built to fail-safe principles, with cylindrical portions metal bonded and conical part riveted. Pressurised between rear bulkhead of nosewheel compartment and circular pressure bulkhead aft of baggage compartment. Nosecone, fairings, nosewheel doors, access doors and cabin floor are of composites materials.
TAIL UNIT: Cantilever fin and fixed incidence tailplane of all-metal primary construction. Leading-edges are made of composites and have integral pneumatic de-icing boots; part of dorsal fin also of composites material. Elevators and rudder (both built by Fuji in Japan) are cable actuated. Elevators are mechanically interconnected, with a fixed tab in each elevator and trim tab in starboard elevator. Rudder is provided with a trim tab, geared balance tab and horn balance.
LANDING GEAR: Retractable tricycle type of Dowty Rotol manufacture, with twin wheels on all units. Main units are attached to wings, retracting rearward hydraulically into rear extension of engine nacelle; nosewheels retract forward. Long-stroke oleo-pneumatic shock absorber in each unit (single-stage on nose unit, double-acting on main units). Goodyear wheels and tyres on all units. Standard main unit tyres are size 34 x 10,75-R16, with pressure of 5.86 bars (85 Ib/sq in); size 37 x 11,75-16 low-pressure tyres (4.00 bars; 58 lb/sq in) are optional. Nosewheel tyres are size 24 x 7,7-10, with pressure of 3.10 bars (45 lb/sq in). Goodyear hydraulic brakes, incorporating anti-skid system. Hydraulic nosewheel steering (±73°); free-castoring angle of ±130° available for towing.
POWER PLANT: Two 1,678 kW (2,250 shp) Pratt & Whitney Canada PW125B turboprops, each driving a Dowty Rotol six-blade propeller with spinner. Propellers have all-composite blades and Beta control. Lucas Aerospace 8,2 kW (11 hp) electric motor for engine starting. Composites materials used in construction of engine air intakes and nacelle cowlings. Fuel in two structural tanks located between the two spars of the central spar box outboard of the engine nacelle, with total standard capacity of 5,136 litres (1,357 US gallons; 1,130 Imp gallons). Single-point pressure refuelling. Engine air intakes, propeller blades and spinners de-iced electrically.
ACCOMMODATION: Crew of two on flight deck, plus two cabin attendants. Standard commuter layout seats 50 passengers, four-abreast with central aisle, at 81 cm (32 in) pitch. Alternative layouts include 46 business class passengers at 86 cm (34 in) pitch, 54 tourist class at 76 cm (30 in), or 58 in high-density arrangement, also at 76 cm (30 in). All layouts mentioned have overhead stowage bins and forward and rear main baggage/cargo compartments as standard, with toilet and wardrobe areas forward and galley at rear of cabin. Downward opening airstair door at front on port side; service door at rear on same side; baggage/cargo door opposite each of these on starboard side. All four doors serve also as Type I emergency exits. Entire accommodation pressurised and air-conditioned. Windscreens anti-iced electrically, flight deck side windows demisted by hot air.
SYSTEMS: Hamilton Standard air-conditioning system. Max pressure differential 0.38 bars (5,46 lb/sq in). Garrett digital cabin pressure control system. Hydraulic system, operating at 207 bars (3,000 lb/sq in) pressure via two engine driven Abex pumps, for landing gear actuation, brakes, nosewheel steering and flap drive. Pneumatic deicing of wing, fin and tailplane leading-edges, using engine bleed air. Primary electrical system powered by a Sundstrand 30/40kVA integrated drive generator mounted on propeller gearbox of each engine, supplying 115/200V three-phase AC at 400Hz, with two 300A transformer-rectifiers and two 43Ah nickel-cadmium batteries for 28V DC power. Optional third (30/40kVA) generator driven by APU. External power socket. APU optional (in rear cone of starboard engine nacelle), for additional electrical power and bleed air for air-conditioning.
AVIONICS: Flight deck has dual Sperry EDZ-801 electronic flight instrument system (EFIS) with CRT displays for primary flight and navigation information, and space provisions for a central multifunction display. Standard avionics include Sperry SPZ-600 AFCS with Cat. I landing; Sperry FZ-500 dual flight director systems; dual Bendix Series III VHF com; single Bendix Series III ADF and DME (latter including frequency hold facility); Bendix Series III ATC transponder; Sperry Primus P-650 weather radar with dual presentation on EFIS; dual Bendix Series III VHF nav with VOR, ILS and marker beacon receiver; TRT AHV-530A (ARINC 552A) radio altimeter with dual presentation on EFIS; dual Litton LTR 81-01 AHRS; Sundstrand Mk II GPWS (ARINC 549); Sperry AZ-800 air data computer; Fairchild A100 (ARINC 557) cockpit voice recorder; Collins 346-2B (ARINC 560) PA system; Sundstrand 980-4100 DXUS (ARINC 573) flight data recorder, incl underwater locator beacon and flight data entry panel; and Teledyne Model 70-275 flight data acquisition unit. Full provisions for Cat. II landing on AFCS and single Collins 628T-2A HF com to ARINC 559A2; space provisions for second ADF, second DME, second ATC transponder, Omega/VLF nav system, and Dorne & Margolin ELT.