I think you got your 60's action heroes mixed up. It was Vic Morrow of "Combat" (not Chuck Connors of Branded) who was killed filming "Twilight Zone, the Movie". Pyrotechnics wet off before the helicopter cleared the danger zone, damaging the tail rotor and Morrow and two child actors were killed during the subsequent crash. The entire sequence was of course, caught on film, which was played during the subsequent civil trial.