On or about 1970 I was a member of a Board of Inquiry on a Tengah Lightning which had caught fire on start up owing to the port wing vent valve seizing and hurling fuel all over the fuselage. They were doing tanker training with a Victor at the time so as part of the investigation I had a look at the tanker's fuel logs on the last sortie this aircraft was on to see if it was doing it then. (it was)
We put in our conclusions but as we were Whirlwind and not Lightning qualified we could not suggest any corrections.
The ventral on a Lightning had an AC pump which was switched on during the start up checks and came on line when the first engine brought the alternator on which caused the overflow. Rather than fix the problem the SOP was changed to switching the ventral pump on at the take off point as enough fuel would have been used so that the wing tank would not be filled before becoming airborne.
A few months later somebody did this followed by a full reheat take off, rotate and climb. The extra fuel in the ventral caused the aircraft to G stall on the rotate and it spiralled into the ground killing the pilot and a villager.
It was nothing to do with me or the other members of the Board but I always backed out of doing another one.