During the 1960s I was studying metallurgy and one of our senior lecturers was called as an expert witness at an inquest of a mechanic who had been killed, when a fan blade of a car he was tuning up had fractured and embedded itself in his skull. This incident was brought back to me during a recent visit to a classic car show when I was looking under the bonnet of a 1930s Hillman Aero Minx and noticed a groove on the bonnet and the inner edge of the wing.

The owner told me that he had been tuning the engine and blipping the throttle, like we all do. He then took it for a short run down the road, heard a bang and stopped to find his fan had fractured and a blade embedded itself in the inner wing. How lucky was he? I know that modern cars have plastic fans, but there must be many classics out there with original metal fans and owners who happily blip the throttle while leaning over the engine. Please ask them to examine the fan on a regular basis and stay out of the arc of a fractured fan blade when blipping the throttle.