Many years ago in far warmer and wetter climes somebody was driving their Whirlwind around Malaysia on a Cat renewel. The trapper gave him odd tasks and small diversions and he followed these to the letter.
Eventually, after lots of prompting the trapper persuaded the candidate to land in a clearing before the engine went quiet. Fuel endurance had been the last thing on the mind of our hero and he was running out. I had to bring a drum of fuel and a pump so they could get back to Changi.
How to fail a 'D' Cat. renewel.