Fuselage, wings, stabilisers, flight-control surfaces and nacelles/pylons.
Notes
Aeroplane structures — summary notes
Free
Main ideas
FUSELAGE (ATA 52/53/56): a semi-monocoque tube of frames, stringers and skin; on pressurised aircraft it is a pressure vessel sealed by forward and aft pressure bulkheads, with reinforced door and window cut-outs and floor beams carrying cabin/cargo loads.
WINGS (ATA 57): built around spars (main load members) with ribs giving the aerofoil shape and stringers/skin resisting bending and torsion; the box between the spars is often an INTEGRAL ('wet') fuel tank using the structure itself.
STABILISERS (ATA 55) and FLIGHT CONTROL SURFACES (ATA 55/57): lighter versions of wing construction; control surfaces are MASS-BALANCED (weight ahead of the hinge) and often aerodynamically balanced to prevent flutter and reduce hinge loads.
NACELLES and PYLONS (ATA 54): support and streamline the engines, carry engine loads into the wing/fuselage and contain a firewall separating the hot engine zone.
Windows, doors, access panels and floor structure are all reinforced cut-outs that must restore the interrupted load paths.
⚠ Exam trap: flight control surfaces are MASS-BALANCED (mass ahead of the hinge line) to prevent flutter; an integral 'wet wing' tank uses the sealed wing box structure as the tank, saving weight.
Solved examples
Why is a mass balance weight fitted forward of the hinge line on an aileron?
Without it, the surface's centre of gravity lies behind the hinge, so a wing bending/vibration can set up a self-exciting coupling between the surface's inertia and the aerodynamic forces — flutter — which can rapidly destroy the structure. A mass balance moves the surface's CG onto or ahead of the hinge line, breaking that coupling and preventing flutter.