The management of civil aircraft airworthiness must embrace three requirements.

• 1. To establish a working system which ensures that airworthiness is achieved.

• 2. To demonstrate to the certification authorities that it has been achieved and

• 3. To ensure that airworthiness is maintained throughout the life of the aircraft.

The sub-contractor’s task has traditionally been one of carrying out appropriate analysis and testing and then to supply to the prime contractor (usually the aircraft constructor) the data on his equipment which is required to satisfy these three requirements. Subsequently he must support this, as necessary, with the operators until the end of the life of the aircraft.