By supertransporter I mean the SuperGuppy (derived from the Stratocruiser), the B747LCF dreamlifter, the A300-600ST, the airbus beluga XL, and any other aircraft whose role is to transport so large pieces that its cargo bay is way larger than the fuselage of aircraft it is derived from (I don't even know if my short list is exhaustive).
The answers of the question How are evolution and variants of aircraft considered by certification authorities? highlight that variants of an aircraft are considered as simple modification of the first type. In the case of super transporters, I imagine this is the same but:
- aerodynamic obviously differs (may be especially relevant for rudder authority and engine out on take off scenario)
- pressurization systems may differ (I guess those aircraft are not pressurized as airliners)
- structural strength and command transmission are affected (cockpit shift, cabin floor in which cable may run suppressed, ...)
Those modifications are heavy and can affect all flight phases.
Given the Beluga XL (resp. the B747 LCF) is basically an A330 (resp. a B747) with modifications, does it share the same type certificate?