SERVICE OF AIRCRAFT AIRFRAME

FUSELAGE. Aircraft fuselage is all metal semi-monocoque with longitudinal structural members including stringers and beams and transverse structural members including frames and working skins. The cross-section of fuselage mid-section is round. Three production breaks along frames No. 8, 28, 40 divide by convention the fuselage into four parts - nose, middle, tail and tip. The fuselage is pressurized from frame No.1 to frame No.38. The canopy of glass cockpit windows is located in upper nose section of fuselage between frames No. 2-5.

Longitudinal structural members includes stringers, equispaced along the section of perimeter and a number of longitudinal beams. All stringers are made of aluminum extrusions and shaped sections of Z-shaped section. The stringers are joined with pads of similar sections and attached to frames by means of bittings and gussets.

The riveted longitudinal beams creak. The side walls of nose landing gear compartment. A cutout in fuselage skin under center wing section is framed around both sides of beams being under center wing section. The central beam is installed from the bottom along aircraft symmetry between frames No. 17-26.

Transverse structural members consists of 44 frames. In dependence on carrying load the frames are divided into heavy, reinforced and typical ones. The heavy frames are: No. 1, 4, 19, 20, 22, 38, 40. The reinforced frames are: No. 3, 4, 9, 12, 30, 32, 41, 42 the rest frames are typical ones. The typical frames are rings of Z-shaped section made of sheet aluminum with hollow punches for stringers, connected to stringers with gussets.

Fuselage stressed skin, attached to longitudinal and transverse members, provides corresponding aerodynamic shape, and withstand the load, acting on fuselage. The skin consist of sheet skins, gussets and pads. The skin is riveted (by means of countersunk head rivets) with frames and stringers.

Panels and floor structure. Fuselage floor is divided into the following segments: cockpit floor, passenger compartment floor, furnishing compartment floor and floor which is underfloor space, all floors, except the underfloor space, is on one level.

Fairings and fillets. They serve to configure for airframe the necessary aerodynamic shape in places of aircraft elements joint, as protection of protruding parts and aircraft accessories. The nose fairing, fillet of center wing section and fuselage, undercarriage fairing, stabilizer and fin fillets and aerial fairing are installed on aircraft.

DOORS, HATCHES. The entrance door-step, service door, cargo door, hatch of underfloor baggage-cargo compartment, upper emergency hatch of cockpit and side emergency hatch are on the aircraft.

WING. The aircraft wing is high-mounted, full cantilever, rectilinear shape in plane on segment between ribs No. 3 and tapered on segment from rib No. 3 to tip. The wing is mounted on fuselage as per top diagram by means of four attachment fittings. Due to span the wing is divided into center wing section and two detachable sections. Center wing section and detachable sections are connected with flange joint. the wing is of torsion-box structure. The torsion-box consists of longitudinal and transverse members. The longitudinal members include two spars and structural panels, transverse ribs. The nose and tail sections of wing and control surface as well as engine attachment fittings are attached to structural members.

Wing control surface. The flaps, and ailerons, which are mounted on wing tail section. Each wing control surfaces. Each section of flap has two attachment fittings, two-element flap and consists of link and fixed deflector. The aileron is located in center eing section between ribs No. 20 and 26. It is suspended to wing by means of three fittings. Servotab and trimming device are attached to aileron beam.

EMPENNAGE. Aircraft enpennage is cantilevert-type tail unit and consists of horizontal and vertical stabilizers.

Horizontal stabilizer consists of two horizontal stabilizer panels, left and right, on each of them the elevator is fitted. The trimming device and servo tab are installed on each elevator. The vertical stabilizer consists of fin, rudder and dorsal fin. The trimming device - servo tab is installed on the rudder. Each horizontal stabilizer panel consists of torsion-box, nose and tail sections. The stabilizer is joined to fuselage along frames No. 38, 40. The fin consists of torsion-box, nose and tail sections, and fairing is installed up. The rudder is installed on rear fin spar, which is fitted to it in 4 points.

Canopy, glazing. The cockpit glazing attaches to canopy main frame, located in fuselage nose section between frames No. 2, 5. The glazing consists of two front windows, two side and two sliding windows. 23 rectangular shape windows are from the both sides of passenger cabin between frames No. 10, 25. Engine nacelle provides typical aerodynamic combination of wing and engine. The main structural sections of the nacelle are: spinner, nacelle front section, engine cowl, cone, cover, fillet of nacelle and wing, channels of cooling system.