Originally Posted by
fantom
Pardon? Did you mean that?
Yes, it is common to put a ferry fuel system into a Twin Otter if you have to move it from one continent to another. The manufacturer provides an AFM supplement with all required guidance and performance data for the overweight operation.
In every case, it is necessary to obtain a special purpose flight permit for the overweight flight from the regulatory authority.
A few hours ago, I landed in Iceland, after departing Canada much earlier today - today's flight was nearly 8 hours long, and it would not have been possible without a ferry fuel system, and sufficient fuel loaded to put the aircraft over the certified MTOW. Naturally, I obtained a special purpose flight permit from the regulator of the state of registry prior to departing on this flight.
Michael