I tried to extract most of the plane from one main cylinder. I had to add two more for the wheels a cone for the nose and 3 more cylinders for the propellers though.
(EDIT) I realised after watching the rest of the lecture that I could have made the cone by extracting the front of the plane in stages, scaling down to zero and then removing the doubles. I could have also made the propellers by extracting sections of the front cone. I guess this is one of those times that theres multiple ways to the same goal.