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NTSB Report
February 4, 1992 · Sikorsky S55B · N1033
Richvale, CA
Overview
Report Status
Probable Cause
Event Type
Accident
Date
February 4, 1992
Injury Outcomes
No injuries (1 uninjured, 1 unknown outcome)
Location
Richvale, CA
Aircraft
Sikorsky S55B
Tail Number
N1033
Operator
Avag
Injuries
None
Aircraft Damage
Substantial
NTSB Number
LAX92LA108
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.
NTSB Probable Cause
THE FAILURE OF THE LATERAL CONTROL ARM IN THE CYCLIC CONTROL SYSTEM.
Full 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.
Flight
Event TypeAccident
Event Time09:30 PST
Nearest AirportRICHVALE (0nm N)
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftSikorsky S55B
Tail NumberN1033
Aircraft CategoryHeli
DamageSubstantial
OperatorAvag
Operating RulePart 137
Engines1
Engine TypeReciprocating
Engine DetailsCurtis Wright · R-1300 · Reciprocating · 800
Seats2
People & Injuries
Injury SummaryNo injuries (1 uninjured, 1 unknown outcome)
Fatal0
Serious0
Minor0
Uninjured1
Total2
Crew 1Age 63 · Second Class
Conditions
ConditionsVMC
LightDaylight
Wind340° @ 10 kt, gusting 10 kt
Visibility50 sm
CeilingNone
Temperature / Dew Point57 / 0 C
Altimeter30.00 inHg
Weather SourcePILO