Accident Sikorsky S-55B N1033,
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ASN Wikibase Occurrence # 364025
 
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Date:Tuesday 4 February 1992
Time:11:30 LT
Type:Silhouette image of generic S55P model; specific model in this crash may look slightly different    
Sikorsky S-55B
Owner/operator:Avag Corporation
Registration: N1033
MSN: 1328
Total airframe hrs:5616 hours
Engine model:CURTIS WRIGHT R-1300
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Category:Accident
Location:Richvale, CA -   United States of America
Phase: Standing
Nature:Agricultural
Departure airport:
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
AS THE HELICOPTER WAS BEING REFUELED IN PREPARATION FOR AN AERIAL APPLICATION FLIGHT, THE PILOT WAS IN THE HELICOPTER AND THE MAIN ROTOR BLADES WERE ROTATING AT 'FLIGHT RPM.' ACCORDING TO THE PILOT, THE HELICOPTER SUDDENLY 'JUMPED ABOUT TWO FEET IN THE AIR AND AT THE SAME TIME ROLLED TO THE RIGHT AND MOVED FORWARD.' THE MAIN ROTOR BLADES STRUCK THE FUEL TRUCK AND THE HELICOPTER ROLLED OVER. AN EXAMINATION OF THE HELICOPTER'S STRUCTURE REVEALED THAT THE LATERAL CONTROL ARM COMPONENT IN THE CYCLIC CONTROL SYSTEM HAD FRACTURED AT A TAPER PIN HOLE. THEREAFTER, THE DISCONNECTED CYCLIC CONTROL SYSTEM PERMITTED THE MAIN ROTOR BLADES TO TILT DOWN, AND THE ROLL OVER WAS UNAVOIDABLE. NO PRE-EXISTING DEFECT WAS REPORTED OBSERVED IN THE LATERAL CONTROL ARM WHEN THE HELICOPTER WAS PREVIOUSLY INSPECTED, ABOUT 14 OPERATIONAL HOURS PRIOR TO THE ACCIDENT.

Probable Cause: THE FAILURE OF THE LATERAL CONTROL ARM IN THE CYCLIC CONTROL SYSTEM.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: LAX92LA108
Status: Investigation completed
Duration: 1 year and 4 months
Download report: Final report

Sources:

NTSB LAX92LA108

Location

Revision history:

Date/timeContributorUpdates
19-Mar-2024 08:39 ASN Update Bot Added

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