The registration worn the aircraft, is one of many registrations that can be transferred between aircraft during prototyping or post-production testing. Production aircraft wear the registration for post-production testing before going through conformity checks and being issued a certificate of airworthiness and its ultimate first registration.
The aircraft serial numbers will be PT for a prototype or PS for a production serial.
PT’s are used for initial testing and then may be retained for years to do development work. Eventually, when no longer of any use they will become gate guards or training aids.
The aircraft in question is a PT serial wearing
a registration used by many aircraft.