The airframe of an aircraft is the equivalent of the chassis - the structural, load-bearing components which hold everything together. On most aircraft, this is not the same as the skin of the fuselage but consists of spars, ribs and braces around which the skin is fitted. The term is also used to refer to the 'base airplane' - for example, special modifications of an airplane are considered to be the 'same airframe' as the production models.