As any airplane owner quickly learns, most types can be modified to some extent through STCs, or supplemental type certificates. From higher-quality sun visors to additional fuel tanks to entirely different engines, an owner can customize their airplane to their liking—provided someone designed that modification, tested it thoroughly, and got it approved by the FAA.
Predictably, less common aircraft types tend to have fewer STCs to choose from. More popular types, however, might have several hundred that have been developed and offered over the years, particularly if the type was produced for a long period of time.
