The designer's problem is trying to anticipate the possible stresses that the structure will have to endure, and to build it sufficiently strong to withstand these. The problem is complicated by the fact that an airplane structure must be light as well as strong. The manufacturer states upon certification that the design meets or exceeds all FAR requirements for the category of aircraft being produced. However, hard landings, gust loads caused by extreme turbulence, performing aerobatic maneuvers in a non-aerobatic airplane, etc,. can affect the airworthiness of one or more major airframe assemblies to the extent that the airplane is no longer airworthy. This reiterates the necessity of operating the aircraft within the limitations outlined by the manufacturer.
Every flight imposes loads and stresses on the aircraft.
How carefully it is flown, therefore, will have an effect on the service life of its assemblies. The fuselage structures of general aviation aircraft today can usually be divided into the truss, monocoque, or the semi-monocoque types. Truss or framework types of construction have wood, steel tube, aluminum tube, or other cross sectional shapes which may be bolted, welded, bonded, pinned, or riveted into a rigid assembly. The vertical and diagonal cross-members are arranged to withstand both tension and compression loads. This type of fuselage has been in use for about 80 years.