Los Angeles Airways Flight 841 was a Sikorsky S-61L helicopter that crashed at 5:50 p.m. on May 22, 1968 in the city of Paramount, California. All twenty passengers and three crewmembers were killed. The aircraft was destroyed by impact and fire. The probable cause of the accident was a mechanical failure in the blade rotor system, which then allowed one blade to strike the side of the fuselage. The other four blades were then thrown out of balance and all five rotor blades broke and then the rear fuselage and tail separated from the rest of the airframe. The cause of the mechanical failure is undetermined.^[2] At the time, it was the worst helicopter accident in U.S. aviation history.^[3]

• http://en.wikipedia.org/wiki/Los Angeles Airways Flight 841