Another of the tristars unique features was the Tri-wing screw - for the uninitiated this was a screw like a Phillips head except it had 3 slots instead of 4.I have drilled these out by the score - what the purpose of this type of head was I have no idea except maybe to sell screwdriver bits - If the aircraft had a problem away from base who the hell had the appropriate screwdriver bits to open panels! Even Rolls had to install them on the engines.