1968 — Aug 14, Los Angeles Airways helicopter rotor failure/crash, Compton CA –all 21

— 21 NTSB AAR. Los Angeles Airways…Helicopter, N300Y Compton, CA Aug 14, 1968. 1969.
— 21 Notable California Aviation Disasters. “The 1960s.” Oct 23, 2008 update.

National Transportation Safety Board Synopsis:

“Los Angeles Airways, Inc., S-61L helicopter, N300Y9 crashed at Compton, California, on August 14, 1968, at approximately 1035 P.d.t. All 18 passengers and three crewmembers were fatally injured, and the aircraft was destroyed by impact and f ire.

“The flight was en route from Los Angeles International Airport to the heliport at Anaheim, California, when the yellow blade, one of five main rotor blades, separated at the spindle which attached the blade to the rotor head. Following the failure, the helicopter was uncontrollable and it fell to the ground.

“The Safety Board determines that the probable cause of this accident was 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 1969, 1)

“….The aircraft crashed in a recreation park located in a residential industrial area.” (NTSB 1969, 3.)

“….This was a nonsurvivable accident.” (NTSB 1969, 4.)

“Examination of the wreckage early in the investigation revealed that a fatigue fracture in the shank of the yellow blade spindle resulted in separation of the yellow main rotor blade, and caused loss of control of the aircraft. It was subsequently determined that no other factors related to the operation of the flight were involved. Consequently, the main thrust of the investigation focused on the circumstances surrounding the cause of the fatigue crack and the failure to detect it.

The fracture was of a type generally described as a high-cycle, low-stress fatigue fracture. A crack was initiated by stresses well below the gross yield strength of the steel and propagated by many thousands of load cycles before the spindle failed completely. It is believed that this crack was present and large enough to be detected during the magnaglo inspection that was conducted at the last overhaul of the spindle. The magnaglo equipment operated by LAA should be capable of detecting cracks as small as 0.010 inch in length under plating of the thickness on spindle AJ-19. It is not known why the crack was not detected.” (NTSB 1969, pp. 8-9.)

“Recommendations

“Initial findings of the investigation revealed that there was strong evidence of a metal fatigue type failure in the rotor blade spindle assembly. Accordingly on August 16, 1968, the following recommendations were made to the FAA:

“Based on its preliminary findings in the Compton crash investigation, the Safety Board today is recommending to the Federal Aviation Administrator that he (1) require an immediate fleet inspection of all Sikorsky S-61 helicopter spindle units; (2) adopt a more precise and frequent inspection to preclude future spindle unit failures; and (3) study the need for establishing a retirement life for this vital part.”

“On the same date the FAA issued a telegraphic Airworthiness Directive which required the following action:

Before further flight, remove main rotor blade spindles P/Ns ~6110-23325-1, ~6110-23325-2 and S6112-23025-1 that either have been “salvaged” . . . or have accumulated 2,400 or more hours-time in service on the effective date of this AD, and replace with blade spindles of the same part number that have not been “salvaged” and that have less than 2,400 hours-time in service….” (NTSB 1969, p.13.)

Notable California Aviation Disasters:
“Date / Time: Wednesday, August 14, 1968 / 10:36 a.m.
“Operator / Flight No.: Los Angeles Airways / Flight 417
“Location: Compton, Calif.

“Details and Probable Cause: Los Angeles Airways suffered its second in-flight disaster in less than three months on the morning of August 14, 1968. The L.A.A. Sikorsky S-61L helicopter (N300Y), flying eastbound from Los Angeles International Airport to the Disneyland-Anaheim heliport located adjacent to the popular theme park, was at an altitude of about 1,500 feet when one of the main rotor head spindles failed and the attached main rotor blade separated completely from the central hub. The resulting imbalance sent the craft spinning out of control and its tail rotor sheared off.

“The helicopter crashed to earth in Lueders Park in Compton and burst into flames, killing all 21 passengers and crew members aboard. Among the victims was passenger Christopher L. Belinn, the 13-year-old grandson of Clarence M. Belinn, the founder and president of the L.A.A. helicopter line. The craft’s severed tail rotor was found three blocks west of the crash site.

“The crash was the result of a metallurgical fault of the main rotor blade spindle, occurring during the manufacture of the unit. Fatalities: 21 — 18 passengers and 3 crew members.” (Notable California Aviation Disasters. “The 1960s.” Oct 23, 2008 update.)

Sources

National Transportation Safety Board. Aircraft Accident Report. Los Angeles Airways, Inc. S-61L Helicopter, N300Y Compton, California August 14, 1968 (NTSB-AAR-69-7). Washington, DC: NTSB, adopted August 27, 1969, 21 pages. Accessed at: http://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-reports/AAR69-07.pdf

Notable California Aviation Disasters. “The 1960s.” Oct 23, 2008 update. Accessed 10/17/2009 at: http://www.jaydeebee1.com/crash60s.html [No longer operable.]