Airworthiness: An Introduction to Aircraft Certification—A Guide to Understanding JAA, EASA, and FAA Standards

Safety must be ensured for all flight operations and aircraft must constantly be maintained in an airworthy state. This means that all maintenance operations listed in the relevant manuals and Airworthiness Directives [1] must be performed.
Continued airworthiness also depends on the particular organizations of operators and maintenance.
Therefore, in extreme synthesis, continued airworthiness is made by:
Maintenance
In a more general sense, certification of operators. [2]
From an airworthiness point of view, there is no such concept as an 'old' [3] aircraft: the term applied is 'used' aircraft. This means that the aircraft's age could influence its commercial value, but not its airworthiness conditions.
Typically, and this also applies to maintenance, we need to know:
What to do
How to do it
Where to do it
Who does it.
These points will now be expanded upon below.
The term 'maintenance' refers to preventive maintenance, alterations and repairs, and introduction of Airworthiness Directives. Airworthiness should depend on the maintenance programs, which also establish the replacement of time change items, the overhaul of engines, propellers, and various parts and appliances.
In Chapter 5 we illustrated that the JAR/FAR 21/EASA Part 21 require Instructions for Continued Airworthiness as a part of the product type certification, but also for the issue of Supplemental type certificates, for approval of changes to type design and major repairs.
Therefore, those instructions become the basic tool for the maintenance of the aircraft because they establish the...