I don’t know enough about the aircraft or it’s fuel system. I would like to understand about useable and unusable quantities and the possibility of sucking air at nose low attitudes with low fuel quantities as well as any cross feed valve fitted.
My back of the envelope fuel calculations would be about the same as Poteroo; 143nm at 92 knots about 95 minutes. About 1.6 hrs at 20 lph - 32l., 10l statutory half hour reserve. 5 - 10l start, taxi and faffing about, makes 47 - 52l required without a climb fuel computation........And that’s before you add your own personal reserve for mum and the kids. Poteroo estimates he could have taken up to 80l.
, in which case there should have been between at least 10 to 40l. in the tanks on landing.