Very interesting Fareastdriver. I have had a look at my logbook for 1956/7 and found my Vampire training hours which were 71 hours dual and 8 hours solo in the T11 with 44 hours solo on the Vampire 5 and the odd 9 we had. I cannot remember any difficulty checking the fuel state on the FB5 and 9, but we had airframe problems with them, especially towards the end of the Swinderby Course. Two FB5's crashed during mid altitude tail chases and then several of us said we had experienced what felt like elevator control reversal when at high IAS and a highish Mach number around 20000 feet. (They had just shown the film The Sound Barrier in Lincoln, but I don't think it affected our reports!) Several De Havilland engineers arrived after the second crash and started to measure the old FB5 and 9's. Most were bent and a high number were outside limits I remember. Nearly all the tail cones were declared dangerous as they were badly dented and could have disturbed the airflow! All the single seaters were grounded for about a month and repair work was started. We were transferred to the hangar and spent a week cleaning the single seaters with a revolting liquid we named virgins pee, then got about half a dozen back and completed the course, which had been extended by four weeks. Happy days!