This month marks the 30th anniversary of the accident at the heliport then atop the Pan Am Building that occurred when a New York Airways Sikorsky helicopter was boarding passengers for a scheduled flight to John F. Kennedy International Airport. In its report about the accident, the National Transportation Safety Board described the event and its probable cause:
About 1735 e.d.t., on May 16, 1977, the right landing gear of a New York Airways, Inc., Sikorsky Model S-61L helicopter, N619PA, failed while the aircraft was parked, with rotors turning, on the rooftop heliport of the Pan Am Building in New York, New York. The aircraft rolled over on its right side and was substantially damaged. Four passengers had boarded the aircraft and other passengers were in the process of boarding. The passengers and the three crewmembers onboard received either minor or no injuries; however, four passengers who were still outside the aircraft and were waiting to board were killed and one was seriously injured. One pedestrian on the corner of Madison Avenue and 43rd Street was killed and another was seriously injured when they were struck by a separated portion of one of the main rotor blades of the aircraft.
The National Transportation Safety Board determines that the probable cause of the accident was the fatigue failure of the upper right forward fitting of the right main landing gear tube assembly. Fatigue originated from a small surface pit of undetermined source. All fatalities were caused by the operating rotor blades as a result of the collapse of the landing gear.The heliport was permanently closed after the accident. Below are a pdf copy of the Times May 17, 1977 report on the accident and links to the NTSB report and a photo of the accident aircraft at airliners.net.
N619PA Photo (at airliners.net)