Tag Archives: Sikorsky S-61L

14 August 1968

Sikorsky S-61L N300Y, Los Angeles Airways, at Disneyland Heliport, Anaheim, California. (Robert Boser)
Sikorsky S-61L N300Y, Los Angeles Airways, at Disneyland Heliport, Anaheim, California. (Robert Boser)

14 August 1968: At 10:28:15 a.m., Pacific Daylight Time, Los Angeles Airways Flight 417, a Sikorsky S-61L helicopter, departed Los Angles International Airport (LAX) on a regularly-scheduled passenger flight to Disneyland, Anaheim, California. On board were a crew of three and eighteen passengers. The aircraft commander, Captain Kenneth L. Waggoner, held an Airline Transport Pilot certificate and was type-rated in the Sikorsky S-55, S-58 and S-61L. He had a total of 5,877:23 flight hours, with 4,300:27 hours in the S-61L. Co-pilot F. Charles Fracker, Jr. had 1,661:18 flight hours, of which 634:18 were in the S-61L. Flight Attendant James A. Black had been employed with LAA for nearly ten years.

At approximately 10:35 a.m., while flying at an estimated altitude of 1,200–1,500 feet (370–460 meters) above the ground, one of the helicopter’s five main rotor blades separated from the aircraft which immediately went out of control, started to break up, and crashed in a recreational park in Compton. All twenty-one persons on board, including the 13-year-old grandson of the airlines’ founder and CEO, were killed.

The Sikorsky S-61 was registered N300Y.  It had been the prototype S-61L, serial number 61031. Los Angeles Airways was the first civil operator of the S-61, purchasing them at a cost of $650,000 each. As of the morning of 14 August 1968, 61031 had accumulated a total of 11,863.64 hours flight time on the airframe (TTAF). It flew an estimated 3.17 hours on the morning of the accident.

The Sikorsky S-61L was a civil variant of the United States Navy HSS-2 Sea King, and was the first helicopter specifically built for airline use. The prototype, N300Y, first flew 2 November 1961. It is a large twin-engine helicopter with a single main rotor/tail rotor configuration. Although HSS-2 fuselage is designed to allow landing on water, the S-61L is not amphibious, having standard fixed landing gear rather than the sponsons of the HSS-2 (and civil S-61N). The S-61L fuselage is 4 feet, 2 inches (1.270 meters) longer than that of the HSS-2. The S-61L is 72 feet, 7 inches (22.123 meters) long and 16 feet, 10 inches (5.131 meters) high, with rotors turning.

The main rotor has five blades and a diameter of 62 feet (18.898 meters). Each blade has a chord of 1 foot, 6.25 inches (0.464 meters). The tail rotor also has five blades and a diameter of 10 feet, 4 inches (3.149 meters). They each have a chord of 7–11/32 inches (0.187 meters). At 100% r.p.m., the main rotor turns 203 r.p.m. and the tail rotor, 1,244 r.p.m. The main rotor turns counter-clockwise, as seen from above. (The advancing blade is on the helicopter’s right side.) The tail rotor turns clockwise, as seen from the left side. (The advancing blade is below.)

The S-61L was powered by two General Electric CT58-140-1 turboshaft engines, each of which was rated for 1,400 shaft horsepower for takeoff and maximum power of 1,500 shaft horsepower for 2½ minutes. The main transmission was rated for 2,300 horsepower, maximum.

The S-61 has a cruise speed of  166 miles per hour (267 kilometers per hour).  The service ceiling is 12,500 feet (3,810 meters). 61031 had a maximum takeoff weight (MTOW) of 19,000 pounds (8,618.3 kilograms).

Between 1958 and 1980, Sikorsky built 794 S-61 series helicopters. 13 were S-61Ls.

The National Transportation Safety Board investigation found that most of the helicopter was contained with a small area of Leuders Park. One main rotor blade, however, was located approximately 0.25 miles (0.40 kilometers) west of the main wreckage. This blade is referred to as the “yellow” blade. (The main rotor blades marked with colored paint for simplicity, red, black, white, yellow, and blue.) Analysis found that this blade’s spindle, where it attached to the main rotor hub assembly, had failed due to a fatigue fracture. It was believed that the fracture began in an area of substandard hardness which was present in the original ingot from which the part was forged, and that inadequate shot-peening of the part during the overhaul process further weakened the spindle.

Diagram of fractured main rotor spindle. (NTSB)
Diagram of fractured main rotor spindle. (NTSB)

Los Angeles Airways had experienced a similar accident only three months earlier which had resulted in the deaths of all 23 persons on board. (Flight 841, 22 May 1968). L.A. Airways never recovered and ceased all operations by 1971.

© 2016, Bryan R. Swopes

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22 May 1968

Los Angeles Airways’ Sikorsky S-61L N300Y at Disneyland Heliport, Anaheim, California. This is the sister ship of N303Y, and it would also be destroyed in a catastrophic accident, 14 August 1968. (Sikorsky Historical Archives)
Los Angeles Airways’ Sikorsky S-61L N300Y at Disneyland Heliport, Anaheim, California. This is the prototype S-61L and the sister ship of N303Y. It would also be destroyed in a catastrophic accident, 14 August 1968. (Sikorsky Historical Archives)

22 May 1968: Los Angeles Airways Flight 841, a Sikorsky S-61L, N303Y, was enroute from Disneyland, Anaheim, California, to Los Angeles international Airport (LAX). Captain John E. Dupies and First Officer Terry R. Herrington were in the cockpit, while Flight Attendant Donald P. Bergman was in the passenger cabin with twenty passengers. The flight was cruising on a westerly heading at 2,000 feet (610 meters) when the five main rotor blades “underwent a series of extreme over-travel excursions in their lead/lag axis.”

The five main rotor blades are identified by color markings: red, black, white, yellow and blue (clockwise as seen from above). As the black blade oscillated fore and aft, the geometry of the pitch change control rods to the blades changed, rapidly varying the blades’ pitch angle and therefore, the lift and drag they produced. This put extreme overloads on the pitch control rods and and the rod controlling the yellow blade failed. The yellow blade was no longer in control. The extreme dynamic changes in the blade’s motion was transmitted to the white blade which also went out of control, followed by the other three blades. All five blades diverged from the normal tip-path plane and began to strike each other and the helicopter’s fuselage. The yellow blade was driven out of its normal sequence between the white and blue blades and struck the fuselage at the baggage door with its top flat against the fuselage side. It broke into five sections then wrapped around the rotor mast. All blades were destroyed. The helicopter, completely out of control, fell nearly vertically to the ground. The crew radioed, “L.A., we’re crashing. Help us.”

At 5:51 p.m., Pacific Daylight Time, Flight 841 crashed on Alondra Boulevard near Minnesota Street in the city of Paramount. The aircraft was completely destroyed by the impact and post-crash fire. All 23 persons on board were killed.

The crash scene of Los Angeles Airways Flight 841, along Alondra Blvd, Paramount, California, 22 May 1968. One main roto rblade can be seen protruding from a building's roof, nearby. (Unattributed)
The crash scene of Los Angeles Airways Flight 841, along Alondra Blvd, Paramount, California, 22 May 1968. One main rotor blade can be seen on a building’s roof, nearby. (Unattributed)

The National Transportation Safety Board (NTSB) investigation determined that the probable cause of the accident was a failure of the black blade’s lead/lag hydraulic damper or a loss of effectiveness of the white blade’s damper. The reason for this failure was not determined.

Captain “Jack” Dupies was a veteran pilot with Los Angeles Airways, having worked for the airline since 1953. He had a total of 12,096 flight hours with 4,208 hours in the S-61. First Officer Herrington had a total of 872 flight hours with 589 hours in helicopters. He had joined Los Angeles Airways in January 1968.

Sikorsky S-61L N303Y, s/n 61060, was completed in June 1962. At the time of the crash, it had accumulated 11,128 total hours on the airframe. It had undergone a complete 2,400-hour overhaul approximately 6 months earlier.

The Sikorsky S-61L was a civil variant of the United States Navy HSS-2 Sea King, and was the first helicopter specifically built for airline use. The prototype, N300Y, first flew 2 November 1961. It is a large twin-engine helicopter with a single main rotor/tail rotor configuration. Although HSS-2 fuselage is designed to allow landing on water, the S-61L is not amphibious, having standard fixed landing gear rather than the sponsons of the HSS-2 (and civil S-61N). The S-61L fuselage is 4 feet, 2 inches (1.270 meters) longer than that of the HSS-2. The S-61L is 72 feet, 7 inches (22.123 meters) long and 16 feet, 10 inches (5.131 meters) high, with rotors turning.

The main rotor has five blades and a diameter of 62 feet (18.898 meters). Each blade has a chord of 1 foot, 6.25 inches (0.464 meters). The tail rotor also has five blades and a diameter of 10 feet, 4 inches (3.149 meters). They each have a chord of 7–11/32 inches (0.187 meters). At 100% r.p.m., the main rotor turns 203 r.p.m. and the tail rotor, 1,244 r.p.m. The main rotor turns counter-clockwise, as seen from above. (The advancing blade is on the helicopter’s right side.) The tail rotor turns clockwise, as seen from the left side. (The advancing blade is below the axis of rotation.)

N303Y was powered by two General Electric CT58-140-1 turboshaft engines, each of which had maximum power rating of 1,400 shaft horsepower for takeoff and 1,500 SHP for 2½ minutes. The main transmission was rated for 2,300 horsepower, maximum.

The S-61 has a cruise speed of  166 miles per hour (267 kilometers per hour).  The service ceiling is 12,500 feet (3,810 meters). The maximum takeoff weight is 20,500 pounds (9,298.6 kilograms).

Between 1958 and 1980, Sikorsky built 794 S-61 series helicopters. 13 were S-61Ls. As of September 2013, two remained in service.

Diagram of Sikorsky S-61L rotor head. (NTSB)
Diagram of Sikorsky S-61L rotor head. (NTSB)

© 2015, Bryan R. Swopes

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16 May 1977

Sikorsky S-61L N619PA
New York Airways’ Sikorsky S-61L, N916PA. (Photograph by Stefan Sjögren, used with permission.)

16 May 1977: At approximately 5:32 p.m. Eastern Standard Time, New York Airways Flight 971, a Sikorsky S-61L helicopter, landed at the Pan Am Building rooftop heliport (JPB) in New York City. Flight 971 had originated at John F. Kennedy International Airport (JFK) and carried 20 passengers and a crew of three. The helipad was 855.23 feet (260.67 meters) above Sea Level.

In the cockpit’s right seat was Captain Lee G. Richmond. Captain Richmond had 11,721 total flight hours with over 9,000 in helicopters and approximately 2,200 in the Sikorsky S-61. He had worked for New York Airways since 1964. The co-pilot was First Officer John F. Flanagan had worked for NYA for about five weeks. He had 1,768.4 flight hours with 1,339.2 hours in helicopters. Both pilots had flown 3 hours, 33 minutes on 16 May. Flight Attendant Lammie Chevalier had been employed by NYA for four years.

A Sikorsky S-61L hovers over the Pan Am Building heliport. (Unattributed)
A New York Airways Sikorsky S-61L hovers over the Pan Am Building heliport. (Pan Am)

Captain Richmond taxied the S-61 into position on the 131-foot × 131-foot (39.9 × 39.9 meters) concrete helipad. While parked at the gate, Richmond kept the rotors turning at 100%, keeping the cyclic control centered and the collective full down (negative pitch). The Automatic Flight Control System (AFCS) was engaged. Flanagan kept his left knee against the collective pitch lever to ensure that it remained full down. Flight Attendant Chevalier stood inside the passenger cabin, supervising departing and boarding passengers.

The return flight to JFK was designated Flight 972.

Aerial photo of the wreck of Flight 972 atop the Pan Am Building, 16 May 1977. (Neal Boenzi/The New York Times)
Aerial photo of the wreck of Flight 972 atop the Pan Am Building, 16 May 1977. (Neal Boenzi/The New York Times)

2 minutes, 21 seconds after touch down, at approximately 5:35 p.m., the right main landing gear of the helicopter failed and the S-61 rolled over to the right. All main rotor blades struck the concrete helipad. Four passengers who were waiting to board were struck by the blades and killed. One of the blades, 28 feet, 10 inches (8.787 meters) long and weighing 209.3 pounds (94.9 kilograms) flew out over the building’s railing and fell alongside the building before crashing through an office window on the 36th floor. The main rotor blade broke into two segments, one of which fell to the street below, striking a pedestrian and killing him. Additional pieces of the main rotor blades were found up to four blocks north of the Pan Am Building.

Wreck of S-61L N619PA at the Pan Am Building rooftop heliport, 16 May 1977. (Unattributed)
Wreck of S-61L N619PA at the Pan Am Building rooftop heliport, 16 May 1977. The Chrysler Building is in the background. (Unattributed)

The helicopter assigned to Flight 971/972 was a Sikorsky S-61L, s/n 61427, registered N619PA. At the time of the accident, the helicopter had a total of 6,913:15 hours on the airframe. Just 7 hours, 22 minutes had elapsed since the last major inspection.

The National Transportation Safety Board (NTSB) investigation determined 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 NTSB determined that the flight crew had performed correctly, and that the aircraft was properly certified, maintained and operated. The Board speculated that the four boarding passengers would have been killed by the helicopter rolling over, even if the engines had been shut down and rotors stopped.

Sikorsky S-61L N619PA lies on its right side at the Pam Am Building heliport, May 1977. The Empire State Building is in the background. (Unattributed)
Sikorsky S-61L N619PA lies on its right side at the Pam Am Building heliport, May 1977. The Empire State Building is in the background. (Unattributed)

A similar accident had occurred when a Los Angeles Helicopters Sikorsky S-61L suffered a fatigue fracture of its right landing gear and rolled over at Los Angeles International Airport (LAX) in 1963. This accident had resulted in a change in the material used to manufacture the parts.

The Sikorsky S-61L was a civil variant of the United States Navy HSS-2 Sea King, and was the first helicopter specifically built for airline use. The prototype, N300Y, first flew 2 November 1961. It is a large twin-engine helicopter with a single main rotor/tail rotor configuration. Although HSS-2 fuselage is designed to allow landing on water, the S-61L is not amphibious, having standard fixed landing gear rather than the sponsons of the HSS-2 (and civil S-61N). The S-61L fuselage is 4 feet, 2 inches (1.270 meters) longer than that of the HSS-2. The S-61L is 72 feet, 7 inches (22.123 meters) long and 16 feet, 10 inches (5.131 meters) high, with rotors turning.

The main rotor has five blades and a diameter of 62 feet (18.898 meters). Each blade has a chord of 1 foot, 6.25 inches (0.464 meters). The tail rotor also has five blades and a diameter of 10 feet, 4 inches (3.149 meters). They each have a chord of 7–11/32 inches (0.187 meters). At 100% r.p.m., the main rotor turns 203 r.p.m. and the tail rotor, 1,244 r.p.m. The main rotor turns counter-clockwise, as seen from above. (The advancing blade is on the helicopter’s right side.) The tail rotor turns clockwise, as seen from the left side. (The advancing blade is below the axis of rotation.)

N619PA was powered by two General Electric CT58-140-2 turboshaft engines, each of which had maximum power rating of 1,400 shaft horsepower for takeoff and 1,500 SHP for 2½ minutes. The main transmission was rated for 2,300 horsepower, maximum.

The S-61 has a cruise speed of  166 miles per hour (267 kilometers per hour). The service ceiling is 12,500 feet (3,810 meters). The maximum takeoff weight is 20,500 pounds (9,298.6 kilograms).

Between 1958 and 1980, Sikorsky built 794 S-61 series helicopters. 13 were S-61Ls. As of May 2017, two remained in service.

© 2017, Bryan R. Swopes

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1 March 1962

Sikorsky S-61L N300Y, Los Angeles Airways, at Disneyland Heliport, Anaheim, California. (Robert Boser)
Sikorsky S-61L N300Y, Los Angeles Airways, at Disneyland Heliport, Anaheim, California. (Robert Boser)

1 March 1962: Los Angeles Airways inaugurated scheduled passenger service utilizing twin-engine, turbine-powered helicopters.

Shown in the photograph above is LAA’s Sikorsky S-61L, FAA registration N300Y, at the Disneyland Heliport, Anaheim, California. LAA was the first civil operator of the S-61, purchasing them at a cost of $650,000, each. N300Y was the prototype S-61L, serial number 61031. On 14 August 1968, N300Y suffered a catastrophic main rotor spindle failure and crashed at Leuders Park, Compton, California. All 21 persons aboard were killed.

Los Angeles Airways began operations in 1947 and continued until 1971. It flew Sikorsky S-51, S-55 and S-61L helicopters.

The Sikorsky S-61L was a civil variant of the United States Navy HSS-2 Sea King and was the first helicopter specifically built for airline use. The prototype, N300Y, first flew 2 November 1961. It is a large twin-engine helicopter with a single main rotor/tail rotor configuration. Although HSS-2 fuselage is designed to allow landing on water, the S-61L is not amphibious, having standard landing gear rather than the sponsons of the HSS-2 (and civil S-61N).

The S-61L fuselage is 4 feet, 2 inches (1.270 meters) longer than that of the HSS-2. The S-61L is 72 feet, 7 inches (22.123 meters) long and 16 feet, 10 inches (5.131 meters) high, with rotors turning. The fully-articulated main rotor has five blades and a diameter of 62 feet (18.898 meters). Each blade has a chord of 1 foot, 6.25 inches (0.464 meters). The tail rotor also has five blades and a diameter of 10 feet, 4 inches (3.149 meters). They each have a chord of 7–11/32 inches (0.187 meters). At 100% NR, the main rotor turns 203 r.p.m. and the tail rotor, 1,244 r.p.m.

The S-61L was powered by two General Electric CT58-110 turboshaft engines, each of which had a continuous power rating of 1,050 shaft horsepower and maximum power of 1,250 shaft horsepower. The main transmission was rated for 2,300 horsepower, maximum.

The S-61 has a cruise speed of  166 miles per hour (267 kilometers per hour). The service ceiling is 12,500 feet (3,810 meters). Its maximum takeoff weight is 20,500 pounds (9,298.6 kilograms).

Between 1958 and 1980, Sikorsky built 794 S-61-series helicopters. 13 were S-61Ls.

Los Angeles Airways’ Sikorsky S-61L N302Y at LAX, 1962. (Mel Lawrence)
Los Angeles Airways’ Sikorsky S-61L N302Y at LAX, 1962. (Mel Lawrence)

© 2016, Bryan R. Swopes

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