A definition of 'airworthiness' can be found in the Italian RAI-ENAC Technical Regulations: 'For an aircraft, or aircraft part, [airworthiness] is the possession of the necessary requirements for flying in safe conditions, within allowable limits.'

In this definition, three key elements deserve special consideration: safe conditions, possession of the necessary requirements, and allowable limits.

1. We can take for granted the meaning of safe conditions relating to the normal course and satisfactory conclusion of the flight.

   According to one definition, safety is the freedom from those conditions that can cause death, injury or illness, damage to/loss of equipment or property, or damage to the environment.

2. Possession of the necessary requirements means that the aircraft, or any of its parts, is designed and built according to studied and tested criteria to fly in safe conditions, as mentioned above.

   Regulations are intended to promote safety by eliminating or mitigating conditions that can cause death, injury, or damage.

   Who establishes these regulations? The airworthiness authorities appointed by the national states. These are obtained through the publication of airworthiness standards (see details in the following chapters) containing a series of design requirements: from the strength of the structures to the flight requirements (flight qualities and performance), criteria for good design practice, systems, fatigue and flutter, necessary tests, flight and maintenance manual content, and so on. These standards are different for different types of aircraft. Obviously, it is not possible to design a sailplane, a 'Jumbo', or a helicopter using the...