I really don't remember fuel fumes coming through the top of the canopy but then the slow roll was one of my favourite manoeuvres and I always flew them perfectly! Being serious now, I do remember one chap on the course ahead of me who had terrible trouble with air sickness in the PP and it was eventually put down to fumes coming through the firewall. He survived and we ended up as fellow DC-10 captains with Fred Laker.