Caledonian
No - to keep the fuselage helped with certification. The existing tubes are only about 1600 hours old and have CAA authority which carry about 32 certificates. A brand new ac requires 50+ and takes longer to get into service. Certification for wings, engines, and ancilliaries require much less; so, NDT the tubes, strap on the bits, pass the test and get flying. Also keeps the costs down. This is what was done and is proven.
The Arax/Arar canoe was never filled with concrete - it was, and still is, retained for aerodynamic purposes. It was intended to house an earlier SatNav, but that's now fitted to the upper rear fuselage because present day aerials are not as clumsy and don't need fairings.
On an engineering point - it's very expensive to modify an ac due to equipement rendundancy, particularly when it affects the external airframe - best heave out the old kit and use the existing space for future developments.
Love many, Trust a few, no cement in my canoe
