Hmmm.. Pre flights for Vulcan crews involved toggling down the mask & inflating the PPJ as a test. Squippers (Called SEWs at the time) suitably qualified had to take the crews through the test. A lengthy business requiring full cooperation of the crew member. Only three test inflations were allowed before the crewman could not fly that day...I often wondered how many times crews who did not want to fly that day `milked` the situation? - The squippers usually got the blame though!
