They had problems with all three aircraft on the eastbound ferry flight after adding the wrong type of engine oil in the Azores. Several engines had to be shut down due to frothing and I seem to remember they diverted into Lisbon. Both remaining B17's were due to fly back together, but due to one being badly unserviceable John Crewdson flew the good B17 back to the USA, leaving the other one behind. I understood it eventually left a month or so later, but I could be wrong. Memory is a fickle thing, but I recall a story about the rudder falling off one of the B17's when it was taxying at Manston!