Please explain. Thanks.
All airplane parts must be traceable. The term "serialized component" generally refers to "rotable" parts—that is, parts that can be removed from the plane and be serviced or rebuilt. Rotable parts usually have a usage limit. For instance, a particular brake assembly or hydraulic pump might need to be removed and serviced after a certain number of hours in the air, or a specified number of takeoffs and landings.
Other components tend to be simple or single-use parts that lack an individual serial number but are traceable by lot or batch number. Some structural components, such as windows and floorboards, are not checked via serial number, because that would require removing the item to find the serial number. Instead they are visually checked for fit, form, and function, and are replaced if there appears to be a problem.
Consumables—including rivets, screws, bolts, o-rings, gaskets and cotter pins—only require traceability for each package or set, and are usually single-use items.
Part-marking with RFID is focused on serialized or rotable parts, because these are the parts for which it is critical that maintenance workers have accurate information regarding the components' histories. Maintenance workers often must remove a part and type its serial number into a computer to retrieve the part's history. This takes time and can potentially lead to mistakes. Having that entire history on a tag would allow personnel to obtain that information out on the tarmac, if necessary, with little or no chance of error.
—Mark Roberti, Founder and Editor, RFID Journal