Sikorsky S-61L crash near Paramount, California, United States

Los Angeles Airways Flight 841, a Sikorsky S-61L (N303Y) operating a scheduled passenger service from Disneyland Heliport in Anaheim to LAX, crashed at 5:50 p.m. onto a dairy farm on Alondra Boulevard in Paramount, California. While cruising westbound at 2,000ft, the main rotor blades underwent extreme lead/lag excursions. One blade struck the fuselage, throwing the remaining four out of balance. All five rotor blades broke, the rear fuselage and tail separated, and the aircraft descended near-vertically. The crew radioed: "L.A., we are crashing, help us!" All 20 passengers and 3 crew were killed. The NTSB determined the probable cause was a failure of the lead/lag hydraulic damper, though the precise origin of the failure was never determined. At the time it was the worst helicopter accident in US aviation history. The sister ship N300Y would be destroyed in an identical accident less than three months later.