Sikorsky S55B N1033

Summary

On 4 February 1992 at about 17:30 local time, a Sikorsky S55B registered N1033, operated by Avag Corporation, was involved in an accident near Richvale, California, United States. 2 people were on board. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

4 February 1992 at 17:30

Classification

Accident

Location

Richvale, California, United States

Nearest airport

Richvale (O97)

Coordinates

39.4807, -121.8398

Aircraft

Sikorsky S55B

Registration

N1033

Category

Helicopter

Engines

1

Operator

Avag Corporation

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX92LA108

Injuries not recorded.

THE FAILURE OF THE LATERAL CONTROL ARM IN THE CYCLIC CONTROL SYSTEM.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB 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.

Quoted verbatim from the NTSB record.