Los Angeles Airways Flight 417
Encyclopedia
Los Angeles Airways Flight 417 was a helicopter that crashed on August 14, 1968 in the city of Compton
, California
. All eighteen passengers and three crewmembers were fatally injured. The aircraft was destroyed by impact and fire. According to the National Transportation Safety Board
the probable cause of the accident was fatigue failure
. The accident happened when the yellow blade, one of five main rotor blades, separated at the spindle which attached the blade to the rotor head. Following failure, the helicopter was uncontrollable and it fell to the ground. The fatigue crack originated in an area of substandard hardness and inadequate shot peening
.
(LAA) Flight 417 was a regularly scheduled passenger flight from Los Angeles International Airport
to the Disneyland Heliport in Anaheim
, California
. The aircraft and crew had completed three round trips to various destinations in the Greater Los Angeles Metropolitan Area
beginning at 0607 PDT and departed the ramp at Los Angeles for Flight 417 at 1026. The flight, operating under Visual Flight Rules
was cleared by Los Angeles Helicopter Control
to take off and proceed eastbound at 10:28:15. At 10:29:30 the flight reported to Hawthorne Tower that it was departing Los Angeles eastbound along Imperial Highway
at 1200 feet (365.8 m). At 10:32:55 Helicopter Control advised, "L.A. four seventeen, seven miles east, radar service terminated." The flight acknowledged, "Four seventeen thank you." This was the last known radio contact with the flight.
Statements were obtained from 91 witnesses. A consensus of their observations indicates that the helicopter was proceeding along a normal flightpath when a loud noise or unusual sound was heard. A main rotor blade was either observed to separate or was seen separated in the vicinity of the main rotor disc. As the helicopter fell in variously described gyrations, the tail cone either folded or separated. In order to establish an approximate altitude for the flight, several simulated flights were conducted in a similar helicopter. Most witnesses indicated the flights at 1200 feet (365.8 m) to 1500 feet (457.2 m) appeared to be most accurate.
N300Y, a Sikorsky S-61
L helicopter, serial number 61031 was the prototype
for the S-61L, and had accumulated 11,863.64 total flying hours prior to the day of the accident. It is estimated that approximately 3.17 hours were flown on August 14, 1968. The aircraft was equipped with two General Electric CT58-140-1
turboshaft
engines.
The aircraft was serviced with 1000 pounds (453.6 kg) of JP-4
fuel
and had a takeoff gross weight of 17185 pounds (7,795 kg), which was below the maximum allowable takeoff weight of 19000 pounds (8,618.3 kg). The computed centre of gravity
at the time of the accident was 260.111 inches (660.7 cm) from datum, which is 267.4 inches (679.2 cm) forward of the main rotor hub centerline. The allow able limits are from 256 inches (650.2 cm) to 278.7 inches (707.9 cm) for a gross weight of 17000 pounds (7,711.1 kg). The estimated gross weight at the time of the accident was 17118 pounds (7,764.6 kg).
:
On the same date the FAA issued Emergency Airworthiness Directive
68-19-07. The directive has since been amended twice and now requires the following action:
.
Compton, California
Compton is a city in southern Los Angeles County, California, United States, southeast of downtown Los Angeles. The city of Compton is one of the oldest cities in the county and on May 11, 1888, was the eighth city to incorporate. The city is considered part of the South side by residents of Los...
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. All eighteen passengers and three crewmembers were fatally injured. The aircraft was destroyed by impact and fire. According to the National Transportation Safety Board
National Transportation Safety Board
The National Transportation Safety Board is an independent U.S. government investigative agency responsible for civil transportation accident investigation. In this role, the NTSB investigates and reports on aviation accidents and incidents, certain types of highway crashes, ship and marine...
the probable cause of the accident was fatigue failure
Fatigue (material)
'In materials science, fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. The nominal maximum stress values are less than the ultimate tensile stress limit, and may be below the yield stress limit of the material.Fatigue occurs...
. The accident happened when the yellow blade, one of five main rotor blades, separated at the spindle which attached the blade to the rotor head. Following failure, the helicopter was uncontrollable and it fell to the ground. The fatigue crack originated in an area of substandard hardness and inadequate shot peening
Shot peening
Shot peening is a cold working process used to produce a compressive residual stress layer and modify mechanical properties of metals. It entails impacting a surface with shot with force sufficient to create plastic deformation...
.
History
Los Angeles AirwaysLos Angeles Airways
Los Angeles Airways was a helicopter airline that was based in Westchester, Los Angeles, California. Los Angeles Airways offered services to area airports as well as Disneyland from Los Angeles International Airport and the heliport at the Newporter Resort, now the Hyatt Regency Newport Beach...
(LAA) Flight 417 was a regularly scheduled passenger flight from Los Angeles International Airport
Los Angeles International Airport
Los Angeles International Airport is the primary airport serving the Greater Los Angeles Area, the second-most populated metropolitan area in the United States. It is most often referred to by its IATA airport code LAX, with the letters pronounced individually...
to the Disneyland Heliport in Anaheim
Anaheim, California
Anaheim is a city in Orange County, California. As of the 2010 United States Census, the city population was about 365,463, making it the most populated city in Orange County, the 10th most-populated city in California, and ranked 54th in the United States...
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. The aircraft and crew had completed three round trips to various destinations in the Greater Los Angeles Metropolitan Area
Greater Los Angeles Area
The Greater Los Angeles Area, or the Southland, is a term used for the Combined Statistical Area sprawled over five counties in the southern part of California, namely Los Angeles County, Orange County, San Bernardino County, Riverside County and Ventura County...
beginning at 0607 PDT and departed the ramp at Los Angeles for Flight 417 at 1026. The flight, operating under Visual Flight Rules
Visual flight rules
Visual flight rules are a set of regulations which allow a pilot to operate an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically, the weather must be better than basic VFR weather minimums, as specified in the rules of the...
was cleared by Los Angeles Helicopter Control
Air traffic control
Air traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...
to take off and proceed eastbound at 10:28:15. At 10:29:30 the flight reported to Hawthorne Tower that it was departing Los Angeles eastbound along Imperial Highway
Imperial Highway
Imperial Highway is a road in Orange and Los Angeles counties in California. It begins at the Anaheim-Orange boundary and runs through several cities until it stops at Dockweiler State Beach in Los Angeles near the Los Angeles International Airport. For much of the way, Imperial Highway is signed...
at 1200 feet (365.8 m). At 10:32:55 Helicopter Control advised, "L.A. four seventeen, seven miles east, radar service terminated." The flight acknowledged, "Four seventeen thank you." This was the last known radio contact with the flight.
Statements were obtained from 91 witnesses. A consensus of their observations indicates that the helicopter was proceeding along a normal flightpath when a loud noise or unusual sound was heard. A main rotor blade was either observed to separate or was seen separated in the vicinity of the main rotor disc. As the helicopter fell in variously described gyrations, the tail cone either folded or separated. In order to establish an approximate altitude for the flight, several simulated flights were conducted in a similar helicopter. Most witnesses indicated the flights at 1200 feet (365.8 m) to 1500 feet (457.2 m) appeared to be most accurate.
Wreckage
The aircraft crashed in Lueders Park in Compton, a recreational park located in a residential area bordering Rosecrans Avenue. The entire fuselage, both engines, main rotor head assembly, four main rotor blades, and the pylon assembly were located in the main impact area. The fifth main rotor blade (yellow) including the sleeve and part of spindle, was located approximately 0.25 mile (0.402335 km) north west of the main wreckage site. Minor parts associated with this rotor blade were scattered over a three-block area northwest of the park. Examination of the yellow blade spindle (S/N AJ19) revealed a fatigue fracture in the shank of the spindle adjacent to the shoulder in the inboard end of the shank.Aircraft
Sikorsky S-61
The Sikorsky S-61L and S-61N are civil variants of the successful SH-3 Sea King helicopter. They are two of the most widely used airliner and oil rig support helicopters built.-Design and development:...
L helicopter, serial number 61031 was the prototype
Prototype
A prototype is an early sample or model built to test a concept or process or to act as a thing to be replicated or learned from.The word prototype derives from the Greek πρωτότυπον , "primitive form", neutral of πρωτότυπος , "original, primitive", from πρῶτος , "first" and τύπος ,...
for the S-61L, and had accumulated 11,863.64 total flying hours prior to the day of the accident. It is estimated that approximately 3.17 hours were flown on August 14, 1968. The aircraft was equipped with two General Electric CT58-140-1
General Electric T58
|-See also:-References:* and...
turboshaft
Turboshaft
A turboshaft engine is a form of gas turbine which is optimized to produce free turbine shaft power, rather than jet thrust...
engines.
The aircraft was serviced with 1000 pounds (453.6 kg) of JP-4
JP-4
JP-4, or JP4 was a jet fuel, specified in 1951 by the U.S. government . It was a 50-50 kerosene-gasoline blend. It has lower flash point than JP-1, but was preferred because of its greater availability. It was the primary U.S. Air Force jet fuel between 1951 and 1995. Its NATO code is F-40...
fuel
Jet fuel
Jet fuel is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is clear to straw-colored in appearance. The most commonly used fuels for commercial aviation are Jet A and Jet A-1 which are produced to a standardized international specification...
and had a takeoff gross weight of 17185 pounds (7,795 kg), which was below the maximum allowable takeoff weight of 19000 pounds (8,618.3 kg). The computed centre of gravity
Center of gravity of an aircraft
The center-of-gravity is the point at which an aircraft would balance if it were possible to suspend it at that point. It is the mass center of the aircraft, or the theoretical point at which the entire weight of the aircraft is assumed to be concentrated. Its distance from the reference datum is...
at the time of the accident was 260.111 inches (660.7 cm) from datum, which is 267.4 inches (679.2 cm) forward of the main rotor hub centerline. The allow able limits are from 256 inches (650.2 cm) to 278.7 inches (707.9 cm) for a gross weight of 17000 pounds (7,711.1 kg). The estimated gross weight at the time of the accident was 17118 pounds (7,764.6 kg).
Findings
In the course of the investigation by the NTSB they made the following findings:- The aircraft gross weight and center of gravity were within limits.
- The crewmembers were qualified for the flight.
- The yellow main rotor blade separated in flight rendering the aircraft uncontrollable.
- Blade separation was due to fatigue failure of the spindle.
- The fatigue crack was a high-cycle, low-stress type which propagated over a long period of time.
- The crack initiated because of a combination of the following factors:
- Metal hardness below specifications associated with a banded microstructure.
- Improper peening of the base metal surface.
- Possible detrimental effect of residual tensile stress from the plating.
- Pitting which may have been present in the base metal surface.
- It is believed that the crack was present at the last magnaglo inspection of the part, and it is not known why it was not detected.
Probable cause
The National Transportation Safety Board determined the probable cause of the accident as the fatigue failure of the yellow main rotor blade spindle, causing separation of the blade which made the aircraft uncontrollable. The fatigue crack originated in an area of substandard hardness and inadequate shot peening.NTSB Recommendation & FAA reaction
Following the initial evidence of a metal fatigue type failure, the National Transportation Safety Board recommended on August 16, 1968 to the Federal Aviation AdministrationFederal Aviation Administration
The Federal Aviation Administration is the national aviation authority of the United States. An agency of the United States Department of Transportation, it has authority to regulate and oversee all aspects of civil aviation in the U.S...
:
On the same date the FAA issued Emergency Airworthiness Directive
Airworthiness Directive
An Airworthiness Directive is a notification to owners and operators of certified aircraft that a known safety deficiency with a particular model of aircraft, engine, avionics or other system exists and must be corrected....
68-19-07. The directive has since been amended twice and now requires the following action:
Notable passengers
Among the victims was passenger Christopher L. Belinn, the 13-year-old grandson of Clarence M. Belinn, the founder and president of Los Angeles AirwaysLos Angeles Airways
Los Angeles Airways was a helicopter airline that was based in Westchester, Los Angeles, California. Los Angeles Airways offered services to area airports as well as Disneyland from Los Angeles International Airport and the heliport at the Newporter Resort, now the Hyatt Regency Newport Beach...
.
See also
- Los Angeles Airways Flight 841Los Angeles Airways Flight 841Los 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 fatally injured. The aircraft was destroyed by impact and fire...
- List of accidents and incidents on commercial airliners
External links
- Amendment 39-2450; Airworthiness Directive 68-19-07
- Air Times: Collector's Guide to Airline Timetables. Shows promotional material listing Disneyland as a destination.
- NTSB Accident Brief on Flight 417
- Los Angeles Airways Helicopter at Disneyland